|Chapter 3||Our Biological Roots: Evolution and Philosophical Issues|
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. Charles Darwin
An abandonment of the hope that we might read a meaning for our lives passively in nature compels us to seek answers within ourselves. Stephen Jay Gould
|more on author|
|Online Edition 2001, 2004, 2011, © Ronald C. Pine||Our Biological Roots|
Evolution is thrilling, liberating, and correct. Stephen Jay Gould
Evolution is both a beautiful concept and an important one, more crucial now to the human welfare, to medical science, and to our understanding of the world than ever before. It’s also deeply persuasive – a theory you can take to the bank. David Quammen
The theory that life has evolved and is ever changing is founded on as much evidence as the broadly accepted generalization that the earth is round. E. Peter Volpe and Peter A. Rosenbaum, Understanding Evolution
|The library of Alexandria, mentioned in
Chapter 2, held many books on subjects remarkably ahead of
Some said the Sun was the center of our planetary system
and that the
stars are very far away; some claimed the human race had
fish. Others dealt with neurology and medicine. The
out on papyrus and parchment in this Egyptian library
culmination of an inquisitive attitude with cultural roots
ancient Greeks. By the so-called Dark Ages this attitude
was no longer
valued, and the library and most of its books had been
common people did not understand the library and were
threatened by its
contents. Eventually even the intellectual leaders of the
become tired of thinking about the secrets of nature.
By 2009, opinion
polls revealed that over half of the people in the
believed in the literal interpretation of the story of
Adam and Eve in
the book of Genesis, and that God created human beings 10,000
ago without evolution playing any role.
substantial percentage (27%) apparently believed that
God and evolution
work together in some fashion, only 13% of the people in
States believed that, once life begins, evolution is a
natural law and that God was not intimately involved in
the steps of
human evolution from other species. Yet Carl Sagan
claimed in his
famous TV show Cosmos
"evolution is a fact, not a theory," and there is almost
agreement among scientists that life on Earth is at
least 4 billion
years old, that the main mechanism of
evolution is a natural law similar to gravity, and that
in or understanding this mechanism is as dangerous as
gravity or the connection between lung cancer and
Obviously, a substantial communication problem exists between science and the general population in the United States, not unlike the days of Alexandria. In this chapter, our purpose will be to explain the theory of the mechanism of evolution, discuss why scientists are so sure it is true and why they believe it is so important to accept it as a reliable belief, examine its epistemological foundation, and explore the very important philosophical implications for an understanding of human nature and the human prospect.
First we must make some important distinctions, between (1) the fact of evolution, (2) the process of evolution, and (3) the mechanism of evolution.
When Sagan referred to evolution as a fact, he meant that we have found substantial observational evidence for the belief that many creatures once existed on this planet that although no longer alive, have an obvious ancestral relationship with creatures that are alive today. It does not require much training to see the relationship between the extinct dinosaurs and modern lizards, but below we will see that the evidence is overwhelming
When we speak of the process of evolution, we are referring to the stages of development that occurred at different times. To name but one particular trail, we find evidence for the existence of only single-celled creatures in the oldest rocks, then in sequentially newer layers of rock, simple creatures that are mere colonies of cells, then worm-like creatures, then jawless fish that look like more sophisticated worms, then fish with jaws, then amphibians (salamander-like creatures), then reptiles (dinosaurs and lizard-like creatures), and then birds and mammals. When this pattern is observed repeatedly all over the world, evolutionary biologists inductively infer that we are uncovering a pattern of stages that occurred on Earth. We are justified in saying that we know that fish evolved before dinosaurs, and dinosaurs much before human beings. From the understanding of the process of evolution, we learn the very important point that a tremendous amount of life existed on Earth for a very long time prior to the evolution of human beings.
The major theoretical issue concerns what major
produced these changes
over such a vast span of time. When the theory of
discussed today, often with controversy, what is being
referred to is
the theory of natural selection, first explained by
Charles Darwin and
Alfred Russell Wallace. Some religious critics of natural
refer to it as "only a theory," implying that it is only
speculation. As a testable theory, it may not be true,
but in terms of
our discussion in Chapter 2, the theory is not just
speculation, a mere
"theory that is out there," according to the Republican
one of the most confirmed and corroborated inductive
our time, a generalization that accounts for such an
amount of data that it serves as a guiding mental
research in many sciences, especially modern biomedical
a highly corroborated and tested theory it is "more than
hypothesis" as Pope John Paul II
noted in 1996
and it has the same status in terms of reliable
knowledge and practical
application as our modern theory of the electron.
||Darwin and Natural
As early as the sixth century B.C., the ancient Greek philosopher Anaximander had proposed that the human species had come from fish-like creatures, and Xenophanes, a contemporary of Anaximander, had noted that layers of rock showed a gradation of animal existence in fossilized pictures. Thus, the concept of evolution was well known by the time of Charles Darwin. Darwin's unique contribution was his rigorous methodology (he spent 22 years accumulating evidence before publishing his theory) and persuasive advocacy of natural selection as the primary mechanism of evolution. Natural selection consists of two major processes: natural variation within a species, and environmental selection.
According to Darwin, physical characteristics of the individuals of a species(2) naturally vary through normal reproduction (mating) and chance mutation, and over a long time when some variations enhance survival value and reproductive advantage, the environment selects those individuals with the right traits that are better adapted to prevailing conditions. In other words, since the characteristics of every plant and animal are different to some extent, when the differences between individuals, major or minor, begin to affect the chances of their living successfully in their environment and producing more offspring, a genetic trend can be established and a new species created. An older genetic trend may branch off and be reproductively isolated from a new trend -- the two groups will not be able to mate -- or the old trend may be eliminated entirely, becoming an extinct species.
As a playful analogy for how natural selection works, suppose that the cultural environment of the human race changed drastically. Suppose that the popularity of the sport of basketball increased to the point that participation became absolutely essential. Everyone must play to survive, and of course, the more successfully one played, the more successful one would likely be at obtaining the fruits of life, being able to afford a family and reproducing. Following Darwin's theory, there would be no mystery if we took off on a very long space voyage and upon returning found that the average height of the human race had increased dramatically. The environment would have selected height as a favorable characteristic.
According to Darwin and his modern followers, initially there would be no natural preference for tall children. Early mothers of the human race would be just as likely to give birth to unusually short children as tall children, depending upon who they mate with and their own heredity. Occasionally, there would be some unusual births, as when a very short woman gave birth to a child who would grow up to be over seven feet tall. However, these unusual births would be no more prevalent than some very tall women giving birth to children who grow up to be very short. Initially the distribution of heights would be random, which means "in no preferred direction." According to natural selection theory, there is no plan directing births in a special direction.
This last point is essential for understanding natural selection theory. In our example, consider what would happen if the sport of horse racing became popular rather than basketball. If it was now essential to be short and light to survive, there would be no mystery if we took off on our space voyage and upon returning found that the average height of the human race had decreased dramatically. According to Darwin's theory, being short or tall is not intrinsically good; it depends on what is happening in the local environment. In the first case, the environment "selects" tallness as a survival characteristic; in the second case being short is a survival characteristic. There is no inherently superior characteristic. Recall the hobbit-sized human relative (Flores Man) example from Chapter 1. Also see Figure 3-1.
Darwin did not originate the phrase "survival of the fittest," and it is a misconception to believe that his theory implies a survival of the most physically capable in terms of brute power. The environment 65 million years ago on Earth did not favor the powerful dinosaur, but an ancestor to the lowly tree shrew began to flourish and evolve into many new creatures, among them, eventually primates and human beings. Prior to this, for millions of years the ancestors to the mammals were small insignificant powerless creatures, living a ghetto-like existence, hiding during the day and venturing forth only at night.
Fitness does not mean that there are inherently "better" physical characteristics. In Chapter 1 we mentioned the cassowary, ostrich, blind mole, and sloth as animals that have lost what seem like very valuable survival characteristics. What is advantageous in one environment is not necessarily so in another. The same can be true with the characteristic of size. The fossil record reveals that one of the first land creatures was an ancestor to the modern tiny millipede. Because it had very little competition, this ancient version obtained the length of a cow. Today, 400 million years later, the descendants of the first millipedes are less than an inch long for a good reason: It is much better to be small when you have a lot of creatures looking for you for a meal.
Darwinism implies a built-in equality of treatment and preference in nature. There are no special creatures, characteristics, or directions.
Life is a copiously branching bush, continually pruned by the grim reaper of extinction, not a ladder of predictable progress. Stephen Jay Gould, Wonderful Life
|Gaining what appears to be advantageous at
time can also lead to extinction at another time, and what
disadvantageous at one time may be advantage at another.
The male of
the now extinct Irish deer had antlers that extended
up to 12 feet with huge palm-like spiked lobes at each
impressive display for the female of the species gave
certain males a
reproductive advantage, but ultimately it was as
functional as a tall
basketball player in a world where horse racing was the
sport. In Chapter 10 we will discuss the alarming
intelligence, an obvious key to our initial success on
this planet, may
now be the characteristic that leads to our
Sickle-cell anemia is a potentially fatal disease, but in
protects against malaria while allowing a person with it
to survive and
reproduce. Similarly, a person who is hypersensitive to
assimilation is at great risk of developing high blood
pressure in a
modern environment of fast food hamburgers and French
fries, but would
have an advantage in an austere environment of low salt
Darwinism implies a built-in equality of treatment and preference in nature. There are no special creatures, characteristics, or directions. Environments exist in which a flimsy mosquito has a much better chance of survival than the most powerful lion. Perhaps this is why there are thousands of species of mosquito. Some bacteria can survive in environments where no human being could, in temperatures close to the boiling point of water. Evolutionary biologists speak of evolution on Earth being like a tree or bush, because no special branches are perceived in the development over time. Every modern animal and plant at the end of each branch, including the human species, is the result of millions of lucky events. And not one, including human beings, has any special guarantee of a long future.
The grand picture that Darwin's simple theory portrays
that every species will have its ten minutes of fame,
its day in the
sun, so to speak, but change in the environment over a
vast time is
inevitable. Although we will discuss below nature's way
lots of the diversity needed for the changing selection
the environment, because having the right
characteristics at the right
time is a matter of enormous contingency, eventually
will not have the characteristics to adapt to the new
environment. Accordingly, it is very important to
Darwin's theory predicts that extinction will be
feature of the natural world. In this sense the
basketball and horse
racing examples above are misleading. From a Darwinian
should not think that it is inevitable that a new
species will always
evolve from an environmental change (tall or short
people). If the
right variation does not occur at the right time, the
and the entire lineage comes to a complete dead end.
branch of the tree of life falls off and ceases to
Remember this crucial point. Darwin's remarkable
that the history of life on Earth will not only show
but also inevitable eliminative failure.
are ignorant, terribly, immensely
ignorant. And our work is, to learn. To observe,
to experiment, to
tabulate, to induce, to deduce. Biology was
never a clearer or more
inviting field for fascinating, joyful, hopeful
work. Vernon Kellogg
Remember from Chapter 2 that science is based on empiricism. The observation of massive extinction in the fossil record is a fundamental reason Darwin's theory is believed to be a reliable belief. When pressed by doubters or religious fundamentalists, supporters of Darwin reply that there are a million facts to support evolution and natural selection theory, in terms of fossil representations in museums all over the world. A fossil is a rock picture of an animal or plant. We know that the overwhelming majority of animals and plants that have lived on Earth have perished leaving no trace of their existence. Flesh and foliage decay, bone and wood eventually turn to dust. Occasionally, a few out of many thousands die under just the right circumstances to produce a fossil, a picture for us to read and contemplate.
Fossils occur in what geologists call sedimentary rock (Figure 3-2), rock that is the result of an accumulation of sediments, solidified by great pressure from the weight of accumulating sediments above. The best circumstance for fossilization is when an animal or plant dies in or falls into a body of water and sediment accumulates to cover it. For the bones of a creature, as the centuries pass, eventually the pressure is great enough to cause the calcium phosphate to undergo a chemical change and turn the bone to stone. In the case of plants, and even soft bodied boneless creatures such as jellyfish, some may maintain their shape just long enough for fossilization to occur. Through our knowledge gained in this century on radioactivity and a simple logic of rock layering, a history of life on Earth can be reconstructed. As described by David Attenborough in his book, Life On Earth,
is there. It’s buried in
rocks of ages. Philip D.
on whale evolution
Seeing Tiktaalik is seeing our history as fish. Neil Shubin, Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body
Almost daily we learn that time is on the side of
The history of life is a story of massive removal followed by differentiation within a few surviving stocks, not the tale of steadily increasing excellence, complexity, and diversity. Stephen Jay Gould, Wonderful Life
|It is an exceptional fate for an animal or
plant to die under just the right circumstances for
Scientists look at this situation in much the same way as
earlier when we discussed the connection between cigarette
lung cancer. Recall that each individual in these studies
could vary in
countless ways, making it impossible to absolutely rule
out some hidden
factor as the real cause of cancer. Similarly, because a
fossil is the
result of an exceptional death, we could have a very
distorted view of
the history of life on this planet. But just as in the
case of the lung
cancer studies, when a consistent pattern begins to emerge
repeated many times, we ought not to be timid in
proclaiming that some
beliefs are more reasonable than others. When rock
Australia have identical dates and similar patters of
fossils as that
of the Grand Canyon, when all over the world a consistent
evidence reveals an evolution from common descent -- from
blue green algae, to protozoa, to colonies of microscopic
as the volvox and sponges, to jellyfish and corals, to
tubular worms, and segmented worms -- with branches to the
insects and shelled worms such as lingulella and clams, to
the nautilus, with land versions of snails and slugs, to
the squid, the
octopus, to crabs, shrimps, and lobsters, to fish,
reptiles, and to mammals -- in spite of the problem of
the element of uncertainty in reading the fossil record, a
person begins to realize that nature is revealing one of
Tomorrow we could find the undisputed fossil remains of human bones in a rock layer where heretofore only ancient trilobites have been found. Our theory of the process of evolution is refutable, and debates rage constantly among scientists about the details. Few doubt, however, that the basic scenario is sound.
The concept of evolution is not only
testable; it has passed an overwhelming number of
some examples. Scientists
recognized based on anatomy and morphology that camels
living in Africa
and llamas living in
when Darwin published his Origin of
Species there were no fossil remains that could
support the view
that humans were also a result of evolution. However, a
little over a
decade later in another book, The
Descent of Man, Darwin made a bold prediction
based on the best
knowledge of the time of the apparent close relationship
of humans to
African apes. He predicted that extinct human-ape-like
someday be found in Africa. Today, after over a hundred
searching paleontologists have found over a dozen extinct species.
paleontologists announced the
discovery of Tiktaalik,
an extinct fish with key transitional features to land
Tiktaalik had forward (pectoral) fins with unique
features that could
allow it to do push-ups. It had a flattened
crocodile-like head rather
than the conical head of a fish. Unlike a typical
fish, it also
had a neck. Most amazing, and for the push-ups, it had
bones that were
clearly the beginning of an upper arm, forearm and
wrist. The patient
paleontologists that found the fossil spent six years
traipsing in and
out of an Arctic island wasteland and another several
extricating the fossil from surrounding rock. But it was
that they were looking where they were looking. Oil and
to feed an exploding global energy appetite, advanced
technology, and Internet data bases of geology all over
allowed a prediction of locations for what would be the
rocks of the
right age and type, and even locations where rocks that
formed over 350
million years ago would be exposed. They also knew from
finds that the transition from water to land for
creatures would be about 360-400 million years
ago. Then with
luck and formidable endurance a fossil of Tiktaalik was
The surrounding rocks were dated at 375 million years
old. Almost daily
we learn that time is on the side of
As we will see, of all the competing theories the
mechanism of natural selection alone predicts massive
Because major variation within a species will occur
changes in the environment, an eventual mismatch between
characteristics and its environment is highly
probable. From an
empirical point of view, an adequate scientific theory
on the details
of life's presence on Earth must not only account for
success, but the massive number of examples of failure
Only Darwin's theory matches the data.
Noah's Ark is a wonderful moral
story about the importance of preserving and
appreciating life in the
face of inevitable natural catastrophe, but it cannot
begin to explain
(as some have tried) the basic empirical details of the
-- the layerings and geological dating of sedimentary
rock and the
world-wide matches of the clustering patterns of fossil
finds in the
dimension of time. For problems with a literal
the Noah's Ark story, see Mark Isaak's Problem
a Global Flood.
Up to a million species have been identified in the
record. At least a billion and perhaps up to 50
may have existed on Earth. Judging from the fossil
of all the species that have lived on Earth are now
extinct. (About 1.8
million living species have been described and
conservative estimates of 10 million living species on
present.) To those trained in anatomy, geology and
is impressive evidence of common ancestry, that each of
the species at
the tips of the evolutionary tree developed from earlier
And again remember this crucial point. For every
survives, innumerable side branches are seen, all living
for a time, but leaving no higher branches. To
take but one
example, the fossil evidence for the evolution of the
(Equus) from a distant ancestor (Eohippus) is remarkably
complete. But this small part of the great
shows at least 20 major side branches over a period of
55 million years
that have no modern descendant. See one version of
this extensive horse
tree from the Florida Museum of Natural History.
Critics of natural selection will often claim that no one has ever observed an instance of evolution. Evolutionists will counter that there are examples of artificial selection all around us. With human beings playing the key role in the environment, we have selected out certain physical characteristics from nature that we have found desirable for our survival.
The ancestor to the modern corn plant was a scrawny weed with only a few seeds. By carefully taking care of the few "freaks" with many seeds and letting the others die, the modern ear of corn has evolved. Early in the twentieth century, the Illinois Agricultural Experiment Station began an experiment that lasted 24 years. An initial crop of corn was grown where the average height of each ear was between 3 1/2 to 4 1/2 feet from the ground. By selecting year after year the ears of corn both lowest and highest from the ground, after 24 years two separate strains were developed. The ears of the low variety averaged only 8 inches off the ground, and those of the high variety, 10 feet!
A similar explanation accounts for cows with large
full of milk, seedless fruit, and the extinction of many
human species has sculpted nature in much the same way
environment has by accident. Furthermore, disease
microorganisms repeatedly become resistant to the drugs
we use to
eradicate them. By chance a few members of a bacterial
species will be
resistant to our drugs. As the others die, those
multiply and a new resistant strain emerges in much the
same way a new
species emerges when a radical change in the environment
causes most of
the members of a species to die. A few may just
happen to have
the right characteristics to live in the new
For the health
and welfare of present and future generations, no aspect
of science is
more important than biomedical science.
no aspect of biomedical science is more important than the
control of microbial diseases. Only
the perspective of natural selection can the dynamics of
bacteria in the human body and in human populations be
understood. Although HIV has
received the most notoriety,
twenty-nine previously unknown human pathogens evolved
between 1977 and
1994 alone. Over 30,000
people in the
Much to the discouragement of vegetable farmers, the same selection process is demonstrated with insects when, after a chemical spray is used for many years to insure high yields, a new resistant version of the insect emerges to devastate their crops. And apparently, much to the chagrin of tax payers who pay the incredible bill for our anti-drug policies, cocoa plants will evolve to be resistant to herbicidal sprays. See Figure 3-4.
A famous example of artificial selection is known as industrial
melanism. In the mid-nineteenth century a peppered
in Great Britain. Its color made it almost invisible
when it landed on
a tree covered with grayish lichen, a type of fungus,
difficult for birds, the moths' natural predator, to
spot them. As the
industrial revolution intensified, smoke and pollution
lichen and darkened the trees, thus making the moths
easy targets for
birds. A "black sheep" version of this moth had appeared
its numbers were suppressed, because birds spotted them
easily. As the
environment changed favorably for their color, they
flourished, and the
grayish variety almost disappeared. In the twentieth
century, a series
of Clean Air Acts were passed to control pollution
emissions. As the
lichen returned and the trees again lightened in color,
peppered variety began to flourish again, and the darker
Can evolution be observed in the laboratory?
Fortunately or unfortunately, evolution is not only
observed, new life
forms are created now routinely by
directly creating the variations (via DNA tinkering)
that match or
don't match particular environments. Multiple
fruit flies have been observed and tinkered with and
generations of Escherichia
bacteria have been tracked. All the experimental
Darwinian predictions. The DNA expression in
embryos of chickens
can be manipulated to produce chickens with teeth (the
teeth) and webbed feet.
Relative to the vast span of time that evolutionary biologists and geologists believe has taken place on Earth, the amount of time consumed by the changes just cited is very small. One of the most obvious deficiencies in the arguments of the critics of natural selection is an egocentric notion of time. They fail to extend the changes capable within these short periods of time to the countless possibilities that could develop given millions and even billions of years of variation and environmental change.
These examples are independent of the fossil evidence for natural selection, but they point to the same conclusion: Life has evolved on this planet through a process of variation and environmental determinism. Physical characteristics emerge either by the laws of heredity, chance mutation, or as we will see below, variation in embryonic development. The environment then determines whether or not characteristics are detrimental, neutral, or convey a selective advantage to a species.
The embryo is the animal in its less modified state …. In two groups of animal, however much they may at present differ from each other in structure and habits, if they pass through the same or similar embryonic stages, we may feel assured that they have both descended from the same or nearly similar parents, and are therefore in that degree closely related. Thus, community in embryonic structure reveals community of descent. Charles Darwin
If you ever feel a need to intimidate or impress someone with your intellectual depth, you might find a way to mention that you have studied the relationship between ontogeny and phylogeny. The embryological growth or development (ontogeny) of a complex organism tends to repeat major characteristics of its evolutionary ancestry (phylogeny). In other words, look at the embryonic growth of an organism and it will show a partial picture of its evolutionary connections with other creatures. Compare the embryonic development of different creatures and you will see remarkable similarities, and the closer in relatedness the closer the similarities. As Darwin noted, "Community of embryonic structure reveals community of descent."
All complex plant and animal life begins from a single cell -- a fertilized egg or seed -- and develops into a colony of cells, and then a multicellular organism. The embryos of animals also display structural similarities. At various stages in its development, a human fetus has gill-like arches similar to fish, a tail like other primates, and a divergent big toe like that of a monkey or ape. In most humans the big toe realigns parallel to the other four toes before birth. For every 100,000 human infants, on average one will be born with a small tail. The amniotic fluid surrounding all embryos of reptiles, birds, and mammals, consists of the same salt content as the sea, the birth place of the first forms of life. The brain of a human being shows a clear pattern of structuring, whereby reptile-like, mammal-like, and primate-like sections appear one on top of the other. Mammalian embryonic growth mirrors the development of ear bones evolving from reptilian jaw bones. The embryos of chickens, bats, and humans all have a web-like connective tissue between their developing toes. In chickens and humans this connective tissue dies before birth. In bats it remains connected to very long fingers to form wings. Just as babies can be born occasionally with a little tail, they can be also born with webbed fingers and/or feet, a condition called Syndactyly. Although Tiktaalik, noted above, clearly showed transitional features of limb bones of land creatures, like all fish, the bone structure for its fins were orientated in the same direction. Four-legged land creatures have forelimbs and hindlimbs facing opposite directions, as humans do as well with elbows and knees facing in opposite directions. But in the early stages of embryonic development all land based creatures, as well as apes and humans, have developing limbs with the same orientation as fish. As the embryo grows the limb orientation rotates, such that forelimb bone structure (elbows for humans) and hindlimb bone structures (knees for humans) have an opposite orientation by the time of birth. As Neil Shubin, one of the discoverers of Tiktaalik, notes in his book Your Inner Fish, ". . . think of trying to walk with your kneecap facing backward." See Figure 3-5.
Fossil evidence indicates that whales and dolphins
from a land ancestor with a dog-like or antelope-like
body. See Figure 3-6.
embryos of both whales and dolphins show evidence of
this phylogeny in
that they have four leglike buds, the two hindmost
reabsorbed before birth and the two front developing
into flippers. The
flippers have an internal bone structure similar to all
mammals. Occasionally, just as in the case of a
child born with a
small tail, a baby dolphin or whale can be observed with
the hind limb
buds still in place. Baleen whale embryos
have teeth at
one stage of development but the teeth are reabsorbed
Vestigial characteristics not only show nature's
important for the raw material of evolution from a
Darwinian point of
view -- but also often show the remnants of an
history. Many snakes have a left-over pelvis and
even tiny legs
buried inside their tubular bodies. Some
flightless beetles have
wings in wing covers that never open, and some blind
moles have eyes
covered with a thin film of skin.
Many forms of animal life that do not give their young a head start within a womb, reveal evidence of their evolutionary ancestry in a larval stage. For instance, fossil evidence indicates that flatworms evolved from coral-like creatures, and as corroborating evidence of this, the larval stage of some flatworm species (there are some 3,000) resemble tiny free-swimming coral organisms. For millions of years one of the most successful creatures on Earth was the ancient trilobite. Some 250 million years ago it became extinct. Its closest living relative is the horseshoe crab. The adult horseshoe crab shows little sign of the segmentation of its ancestor, the circular grooves that run perpendicular to the length of the trilobite's body -- a common physiological mechanism found in worms and insects. However, the newly hatched offspring of the horseshoe crab show this segmentation before developing the shelled armor of the adult. For this reason, they are called trilobite larvae. Finally, as many of us observed as children, frogs begin their lives as fishlike creatures (tadpoles). The mink frog develops for two years in water. Amphibians (frogs and salamanders) evolved from fish.
biology makes sense except in the light of
. . in addition to helping decide the
survival of the fittest, the environment is also
arrival of the fittest. Scott
David Epel, Ecological Developmental Biology
. . . our history is written within our
development from egg to adult. Embryos hold the
clues to some of the
profound mysteries of life. Neil Shubin, Your Inner Fish
. . . nothing here negates the importance
of natural selection. Evolution by natural selection
is the way of the
world, and Charles Darwin's key contribution to the
patrimony of humankind. Even plasticity is a
David Epel, Ecological Developmental Biology
Cell and Deoxyribonucleic Acid
Major evidential support for the theory of natural selection is the discovery that just as the endless variety and arrangement of words are different sequences of the same letters, the physical development of all life on Earth, and its diversity, is directed by different sequencing and expression patterns of the same chemicals. The same basic percentage of composition of water, salts, carbohydrates, amino acids, nucleotides, and fats exist in the lowly bacteria as in the cells of a human being. Six basic elements -- carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur -- make up 99% of the composition of all life on Earth.
The basis of all life is deoxyribonucleic acid or DNA. With the exception of a few viruses, in the deepest recesses of the cells of every form of life is a 30 billion atom long molecule. This molecule is the coded instructions for the overall directional development and form for every living thing on Earth. The basic pieces of this very long molecule are the same for a human being as that of a tree. There are only four "letters" for the language of life. The alphabet may be small, but the words are very long. Each living thing is like a different play or drama written in the same language. With the same chemical alphabet, different words are constructed, and the different words are arranged to form different meanings and works of art. The difference between a human being and a tree is the arrangement of letters and words and how these letters in turn form genes and different arrangements of genes. The genes convey a direction to the development of physical structures, functions, and behavioral tendencies.
The evidence for this genetic basis to life is
overwhelming. The corroborative force of genetic
evidence for natural
selection theory is startling. More so now with
major advances in
gene reading technology. Geneticists, microbiologists,
involved in biomedical research now have tools that can
DNA sequences not only of humans but many other
creatures from microbes
to apes. Every creature alive today has DNA full of
Chickens have genes for teeth that are no longer
fish and moles have fossil genes for the potential
development of fully
functioning eyes that no longer work. Antarctic icefish
are the only
vertebrates known that do not have red blood. If they
did their blood
would freeze solid. But they have the fossil genes for
vertebrate blood and the gradual genetic changes that
over millions of years from their red blooded ancestors
can be mapped
in remarkable correspondence with the independent
of plate tectonics that moved and isolated Antarctica.
Whales and dolphins still have the fossil genes for
smell from their land dwelling ancestors. Humans have
genes for the making of Vitamin C internally in our
livers that now
have too many mutations to work as they did in our
ancestors and still
do in our vertebrate relatives. Your dog does not
need to consume
any Vitamin C to survive. We have to eat a lot of fruit
because we are
all born with a genetic disease. So do our closest
orangutans, gorillas, and chimps. Somewhere in our
primate lineage a
common ancestor to humans and apes lost the ability to
own Vitamin C in its liver.
Linking animal morphological and behavioral
in evolutionary relationships can now be corroborated by
their genes. Anatomical, behavioral, and fossil
humans with our ape cousins. A comparison of our
genes with those
of apes reveals a remarkable close relationship.
99% of our genes
are the same. Even the complex molecules of the blood of
chimpanzees are virtually identical.
In the twentieth century we began to learn how to tinker with genes and produce different physical characteristics and functions in various forms of life. A major ethical issue for the twenty-first century is: How much life should we change this way? Through genetic recombination we can produce bacteria that eat oil and help clean up pollution, plants that produce biodegradable plastic polymers in their leaves, possibly cure cancer, eliminate many genetically based diseases such as cystic fibrosis, and manipulate stem cells to produce perfectly matched replacement organs for seriously ill people. We will also, however, probably have the knowledge to make diabolical biological weapons, such as a slow virus that will infect only a particular ethnicity, and clone particular types of people, such as football and basketball players, or at least enhance muscle tissue in such a way to avoid drug testing in competitive sports. The understanding of natural selection as a law of nature will be crucial for making the right choices in using this new biotechnology. We will need to know what is true to decide what is right.
Darwin was not aware of the mechanism of genetic variation, DNA replication, and radiation-induced mutation. We have learned since Darwin's time that just as mistakes can be made in the retyping of a play, subtle copy mistakes can be made in DNA. Also, just as outside electromagnetic forces can cause drastic changes in the information encoded on electromagnetic media, such as a computer disk, so minute outside forces, such as cosmic radiation, can alter a small segment of the 30 billion atom staircase of DNA and produce mutations. From this potential disorder, an wide variety of change is possible. The majority of the changes are detrimental to the individual, because it is very unlikely that these changes will match what is needed to live successfully in the environment. Some of the changes will be neutral, but a few lucky matches are possible given enough time. The science of microbiology has corroborated much of Darwin's original theory. To help the nonspecialist understand what the microbiologist has discovered, and how it relates to the mechanism of natural selection, science authors Gerald Feinberg and Robert Shapiro have offered the following analogy.
For illustration purposes, the giraffe can be viewed as updated Hamlet. Although there is no direct fossil evidence for this particular story, the following is a likely Darwinian scenario. Millions of years ago the environment of the ancestor to the modern day giraffe (the Pre-Okapi) was becoming drier. See Figure 3-7. The first foliage to die would be the lower bushes and grasses. The last would be the large trees. As this process continued gradually over thousands of years any animal that had a feeding advantage would be more likely to survive and reproduce. Within this time a series of mutations, coupled with normal genetic variation, produced a creature with a longer neck and legs. Evolutionary biologists debate whether this would be a very gradual process emerging over thousands and thousands of generations or would be relatively sudden (geologically speaking), or whether the long neck served no useful purpose at first or whether it was useful for other purposes. What they agree on is that evolution of a new species surely took place from an Opaki-like ancestor and that for a Darwinian scenario to apply, through genetic variation and mutation a much different animal emerged while the ancestor perished, a new play in the drama of life, one that now had an advantage in being able to eat the topmost leaves of acacia trees. From a Darwinian perspective, it is very important to consider that if the environment had not changed at the time of the mutations, the ancestor of the giraffe might still be with us. If the series of mutations and accumulative inherited variations had not occurred at the right time, there would be no long-necked giraffes, and the entire lineage may have died out completely. No ancestor and no giraffe; just a dead end. Just as plays do not survive if the response of the audience and reviewers is negative, so species do not survive unless they play to good reviews from the environment.
No, we are not going to talk now about a rock-band. The above Hamlet analogy is used to help us understand the importance of genes and genetic variation as a key part of the modern theory of natural selection. Misleading is to think that changing the words alone is the only way to get variation and selection of the best changes for a new updated play. The different actors can surely change the play by how they deliver their parts. The timing and emphasis of particular parts of the dialogue could be changed. Scenes can be decorated and constructed differently. The timing of entrances and exits could vary. A theater director could have his or her own ideas on how various parts of the play should be done to help a modern audience enjoy the play more. And note that these possible changes would be much more immediate than waiting for random, chance changes in the words. A theater director and the various actors could even change some characteristics of the delivery in the middle of a nightly performance depending on how they evaluate the audience reaction. Notice that by applying these more immediate "epi-word" changes, the play could be kept alive so to speak (being popular enough to survive) for more time to allow for the fortuitous word changes noted in the analogy above. Misleading also is that the possible changes are not infinite. To still be the play Hamlet there would need to be some directional constraints and channeling of the types of changes on top of a foundation of scenes and subplots.
Applying this analogy to evolution theory, except for the conscious effort in the analogy of the actors and director, what are called epigenetic changes (changes in traits without changes in the genes) can also be involved in producing variation for selection. Tremendous progress in the sequencing of DNA in humans as well as many animals and microbes has not only shown a deep ancestral connectivity of all life on Earth, but awareness that the creation of the variation needed for evolution can have multiple sources. Within a species, during embryonic development different sequences of genes can be switched on or off producing different traits, even though there is no difference in the original letters. Plus, closely related species can be distinctly different in many ways but still have 99% of their genes the same. Furthermore, for the amount of variation needed (the more the better) for environmental selection, evolution, and the creation of new species, the genes may get some help from the environment prior to selection. The environment may instruct as well as select. Genes might stay the same but be expressed differently as a source of variation. The ecology (the eco-part) can have a major impact on the embryonic development of a organism (the devo-part), and both can be a major source for the variation for selection to take place and produce species novelty (the evo-part).
Applied to natural selection theory, the strict interpretation of the Hamlet analogy above implies that since a particular type of fish once existed as the ancestor to the human species, if we could compare the genes of our fish ancestor to that of humans today, we would find that most of the genes have now been completely replaced. To replace an old play with a modern version lots of the words would have to be replaced. Surely the genes of a complicated, sophisticated human capable of modern computer, tablet, and smart phone technology, a global communication and economic system, and understanding the universe in such detail must be very different from a simple fish. Not so; we need to extend natural selection theory in the light of recent discoveries. The story is much more interesting and supports the reality of evolution at a much more substantial and deeper level. The same "toolkit" genes that build a body of a fish with a front to back orientation and limbs for fins also exist in humans. They have been duplicated and changed significantly, but it is like seeing the same theme repeated in different versions of Hamlet. Even better, with modern genetic techniques we can study the genes comparatively between different species. We can not only marvel at the similarities of structure during embryological development, but witness how similar tool kit genes have been modified and expression patterns changed to produce different forms -- how for instance the genes that govern the development of a fin in a fish are changed in the development of a limb for a land dwelling creature. The genomic revolution has produced such persuasive evidence that it is almost as if a modern version of Hamlet came with not only some changes in the words and expression patterns but explanatory notes for how and when the changes were made. Remember also that fossil genes can also be examined to tell a corroborative story of the ancestral history of a species.
Let's look now at some examples of how the environment can influence the development of forms of life. A water flea can develop a normal rounded head or its head can grow to twice the normal size and have a spiked-liked helmet. This spiked helmet form occurs when the developing water flea detects any chemical signature of one of its predators in the water, including chemicals released from water fleas being digested in the guts of a fish. Its tail also becomes more spiked and overall the water flea is harder to eat for some of its predators in this prickly shape. Amazingly, this prickly shape expression will also be inherited for a few generations even though the genes of the water flea do not change. Important to note for later, as wonderful as this predator induced defensive process is there is some loss in potential fitness. There will be less energy available to produce eggs. Similarly, male dung beetles will grow horns during larval development provided they are given enough (excuse the expression) shit (dung) at the right time of development. Again there is a cost -- reduced penis and testes size. Many males will lack horns but they still manage to mate with females. While the horned males are guarding the entrance to female tunnels, the hornless males create "sneaker" tunnels that intersect with the horn-protected tunnels and mate with receptive females at the bottom of the tunnels, presumably using better endowed sexual organs. Next, a bee larva will become a worker or a queen depending what it is fed. If a queen dies, a larva will be fed "royal jelly" by a worker and turn into a new queen within a few weeks. The caterpillar version of the hornworm moth will be green or black depending on the temperature and what time of year it is when eggs are laid. The black form is better for a colder temperature because it enables the caterpillar to absorb more heat. The green version is better for camouflage in warmer times of the year when the caterpillars are roaming around on green foliage.
Here we have seen examples of predator, nutrition, and temperature induced forms of life. The genes have not been changed to induce these different forms. Finally, and perhaps most spectacular are sex changes in creatures due to environmental influences. Many reptile species, such as species of alligators, crocodiles, and turtles, produce more males or females depending on temperature. Perhaps most spectacular, since a sex change occurs after a fish is formed and swimming around, the blue-headed wrasse can change from an immature state to male or female and a mature female can change to a male depending on whether there is another male in a cluster of females. Clusters of females usually live with a single, large blue-headed male. If the male of a group dies, one of the females will turn into a large and very different looking male. If an immature wrasse arrives in the range of a cluster and there is a male already present, it will turn into a female.
The key point to remember is that the environment can "instruct" the direction of variation produced. There is flexibility, a built in plasticity to what bodily forms are created. But just as actors and theater directors could not vary the performance of Hamlet unless the words were there to allow for the variation, so genes must make the plasticity possible and the level of plasticity may also be an evolutionary quality -- some creatures are capable of more flexibility by allowing for considerable environmental influences on development.
It is also important to note that plasticity is not inherently good. Evolution by natural selection produces a messy tinkering process of compromise and trade-offs. No new biological trait will be 100% good news. Recall that there were downsides to the form-flexibility of the water flea and dung beetle. Plus the future environment will not always match the form predicted as adaptable based on initial environmental cues during development. For instance, similar to the green and black forms of the hornworm moth, some species of weasels and foxes have alternative brown and white fur forms dependent upon the temperature and length of the day. Better to be white during winter, provided that the environment is a snow filled winter wonderland. Now with global warming instances have increased in areas of weasel and fox habitation of cold winters without snow. These animals are not chameleons; they cannot magically turn back into their brown forms when there is no snow. Knowing that environmental cues during development are crucial for the human fetus, we advise pregnant women to maintain good nutrition, get plenty of folic acid and other vitamins, and avoid drugs and alcohol. In much of the world and for much of human history, the environment for the fetus and mother has been less than optimal. In response humans have evolved a metabolic plasticity. A less than optimal nutritional environment for a fetus will program the creation a human body to burn calories slowly and conserve as many calories as possible for the production and storage of fat, in anticipation of a poor nutritional environment as a child and adult. Not good if that body grows up in a world full of fast-food calorie meals. Obesity, diabetes, and heart disease are the all too common result.
For the big picture, remember Embryos, Genes, and Fossils. An important contemporary integration has occurred of embryology (the study of development) and the genomic revolution, with hundreds of years of patient accumulation of a fossil record to show that the evidence is overwhelming that Darwin had it basically right -- there has been evolution of the amazing diversity we see on Earth today from a common ancestry. That ancestry is as deep (with billions of species that no longer exist) as it is long (billions of years). Think also of Gain, Modification, and Loss, of traits that are adaptations in one environment and flaws in another. Humans and our close primate relatives have lost the ability to make Vitamin C, a crucial ingredient in the production of collagen, a "glue" that all multicellular creatures need to keep cells together to form an organism. We have gained a lot from an upright posture and large brain, but our postures put tremendous stress on knees and spines that evolved for a life as a four-legged creature and our brains are stressing the entire planet with their destructive creations.
If the historical development of science has indeed sometimes pricked our vanity, it has not plunged us into an abyss of immorality ... it has liberated us from misconceptions, and thereby aided us in our moral progress. Philip Kitcher
As noted previously, a remarkably humbling philosophical implication follows from the theory of natural selection. Evolution has no direction and no purpose in the sense that there is no inevitable, unswerving progress to "higher" creatures. There is the spectacular result of happenstance and contingent interaction with local environments. There is also a dance of interaction and cooperation with the environment and the ecological situation life forms find themselves in. Plus, once evolution began in earnest there were tool kit constraints and channels open for variation. Not just anything was possible. It is no accident that we don't see creatures with wheel-like roller skate feet. The tool kit genes for limbs would have to be completely replaced and the gradual nature of gene changes and natural selection does not work this way. Mutations, and copy mistakes are common, but they are boxed in to some extent with what came before. We have learned that given enough time, chance, constraints, and interaction with the environment can produce incredible works of adaptation. There is no superior adaptation; there is only adaptation or death. Furthermore, adaptations are not perfect and they are almost always temporary. There may be more complex adaptations, but there is no guarantee that complexity is better than simplicity.
When human beings survey the biosphere, our art, our history, and our technological achievements appear superior to that of other creatures. An objective observer, however, from another world might very well conclude that insects are the dominant creatures, and that the insect body is the most adaptable for living on this planet. As David Attenborough has pointed out,
Human beings are very purposeful creatures, and it is difficult for us to think of anything that does not have a purpose, just as it is difficult for us to conceive any event taking place that was not caused by something. It is much easier for us to believe that our species is special, not only because there appears to be evidence for it -- our art, our science, our technology -- but also because we want to be part of a universe that is meaningful and goal-directed. But "purpose" is a human concept, and we must guard against interpreting everything through human filters, as if these are the only filters possible.
Our climb to the top has been a get-rich-quick story, and, like all nouveaux riches, we are very sensitive about our background. Desmond Morris
After religious leaders refine religion in accordance with its true purpose, they will surely recognize with joy that true religion has been ennobled and made more profound by scientific knowledge. The further the spiritual evolution of mankind advances, the more certain it seems to me that the path to genuine religiosity does not lie through the fear of life, and the fear of death, and blind faith, but through striving after rational knowledge. Albert Einstein
|We may or may not be the only intelligent
creature on Earth, or the entire universe for that matter,
but there is
no guarantee that the use of intelligence is a superior
guaranteeing its possessor a long life time geologically
that it is part of any plan. For all we know, intelligence
characteristic that will soon go the way of the
What we call intelligence could be nothing
more than another brief experiment. It is not comforting
to witness day
after day so much of our intellectual resources devoted to
manipulation, exploitation, and developing devices of
as nuclear, chemical, biological, and robotic weapons.
There is an important message in this view of life.
its attitudinal focus is humility, natural selection as
a law of nature
is not necessarily inconsistent with a belief in a
anymore than believing in the law of gravity is
inconsistent with being
a Christian, a Jew, or a Muslim. However, our consistent
bias of our "specialness," which permeates most of our
philosophies, and politics -- this bias that somehow we
a necessary survival and justice -- has led us
repeatedly to indulge in
frivolous destructive behavior. Throughout human history
violence -- of people killing, mutilating, and raping
other people --
has not been perpetuated by a few deranged individuals,
but rather by
organized societies convinced of their superiority. Even
a casual study
of historical and contemporary national conflicts,
reveal people who
believe that their existence is so special that death in
a "just" war
guarantees a reservation in heaven. In the 1980s there
were people in
the United States who did not fear nuclear war with the
They believed that as a Christian nation, if the world
was destroyed in
a nuclear holocaust, we would still win because our
place in heaven
would be guaranteed.(7)
radical Islamists believe they will be assured of a
special place in
heaven by killing people they disagree with religiously
We take pride in our potential for empathy, compassion, and a higher value system. Yet, until recently manufacturers of women's makeup routinely used the eyes of rabbits to test for toxicity of new inventions. When the new chemical was dropped into their eyes, if the rabbits became blind, it was discarded along with the now handicapped rabbits. We continuously keep cows impregnated to produce milk, and then kill the majority of the baby calves born, producing veal cutlets and sweetbreads (the thymus gland) for fancy French restaurants. And there is our steak from steers, made possible by castrating millions of the young bulls each year.
The Greek philosopher Aristotle interpreted all life in terms of hierarchy and declared, "Plants exist for the sake of animals, and brute beasts for the sake of man." The eighteenth-century German philosopher Kant reinforced this view: "So far as animals are concerned, we have no direct moral duties; animals are not self-conscious and are there merely as a means to an end . . . . that end is man." The Bible declares that humans have dominion over the rest of the biological world, but there is no evidence from natural selection to support an Aristotelian or Kantian interpretation of this statement.
The perspective that natural selection provides, added to the cosmological perspective discussed in Chapter 1, can serve as a foundation for a humanitarian value system, for an authentic attitude of preciousness and sustainability. According to Albert Einstein, science has been wrongly accused of undermining morality, yet it "widens our circle of compassion" and is consistent, he argued, with the most essential religious outlook and our highest ethical aspirations.(8)
As Darwin noted there is "grandeur in this view" of life, that so much beautiful diversity could be produced through an equality of chance. If there is any value that is supported by natural selection theory, it is that diversity is good. If the goal is survival of life, then natural selection teaches us that diversity is the means to that goal. Further moral implications follow from this awareness. If we care about promoting the future of the human race, we must care about all creatures and our role on this Earth should be at best one of stewardship. If it matters to you that your children will have children, and their children will have children, and so on for a very long time, then racism and ethnic cleansing are massively inconsistent with preserving the diversity that will be needed within the human population to match an inevitable changing environment, such as the ever-evolving microorganisms that will cause new diseases.
Einstein argued that true religion and science "are branches from the same tree."(9) Their common philosophical enemy is self-centeredness. Their common solution is a picture of a cosmic setting that shows us to be part of a wondrous foreboding power that teaches us to care about all life and walk humbly.
For Lamarck, variation is the result of a directional, purposeful adaptive response to a changing environment. For Darwin, variation based on a genetic foundation comes first, and selection or rejection by the environment afterwards. For Lamarck, changes in the environment have priority; these changes cause improved creatures. . .
In the natural selection scenario, a long-necked giraffe is originally most likely the long-term result of natural reproductive variation, a series of copy mistakes, and mutations. If the environment does not change, the variational changes are usually useless and the creature dies. If the right variational changes do not occur when the environment changes, the entire species may become extinct. Only in rare instances will the right set of characteristics be around when the environment changes in a fundamental way.
If God exists, why would He not be a Darwinian?
To people of faith, what evolution says is that nature is complete . . . God fashioned a material world in which truly free, truly independent beings could evolve. Kenneth R. Miller, Finding Darwin's God
the Inheritance of Acquired Characteristics
It is important to distinguish Darwin's theory of natural selection from the view first proposed by the French biologist Lamarck. Introduced a half century before Darwin, it is now called the inheritance of acquired characteristics. Unlike the scientifically supported Darwinian view, this theory states that the variation observed in nature and the amazing adaptability of life are not the result of a chance meeting of genetic variation and environmental change. For Lamarck, variation is the primary result of a directional, purposeful adaptive response to a changing environment. For Darwin, variation based on a genetic foundation comes first, and selection or rejection by the environment afterwards. For Lamarck, changes in the environment have priority; these changes cause improved creatures by directly affecting heritable genes. Following our play analogy, an updated Hamlet is produced in a more guaranteed way as the right words are placed in the right places to make sense to a new audience. For modern followers of Lamarck, there is not only epigenetic change and change in gene expression directly influenced by the environment, but core DNA sequences and new genes would be created via environmental stimulus.
The Lamarckian story says there is an inherent wisdom in evolution. Instead of unplanned genetic changes, only a very few of which may match a changing environment, there are purposeful genetic changes and a virtual guarantee of many adaptations to a new environment. Thus, a direct communication link is proposed between the changing environment, a creature's response to the environment, and DNA in the germ or sex cells. A creature that experiences a radically changing environment will begin to behave in a certain way, either using or disusing its inherited characteristics, in attempting to adapt to the new environment. This behavior in turn will produce acquired characteristics which will then result in the production of offspring that are more adaptable to that environment.
In the giraffe example, long-necked giraffes would
predominate in a much more directed way than in the
The elevating of the food source of the pre-Okapi would
stretching of the muscles of the legs and neck,
eventually resulting in
offspring with longer legs and necks. Somehow the new
cause a change in the animal's genes. In the natural
scenario, a long-necked giraffe is originally most
likely the long-term
result of natural reproductive variation, a series of
and mutations. If the environment does not change, the
changes are usually useless and the creature dies. Or,
the creature is
not able to mate. If the right
variational changes do not occur when the environment
entire species may become extinct. Only in rare
instances will the
right set of characteristics be around when the
environment changes in
a fundamental way. Hence, even granting the possibility
and flexible changes in form due to environmental
Darwinian scenario predicts a much messier long term
Given enough time, life will go badly for a species.
Recall the Antarctic icefish. We can study the eroded,
mutated, and fossilized genes related to the former
production of red
blood cells. Evidence is substantial that most of its
close relatives are extinct, most dying because they did
not have the
right blood at the right time to withstand severe cold.
gradual changes that allowed another ancestor to slip
environmental window of gradual cooling of its
environment is not
likely to be repeated backwards if global warming
current temperatures in the Antarctic. It will most
likely be another
wonderful example of an amazing adaptation that had its
day in the sun
(shall we say cold water) that was relatively long but
Darwin argued that natural selection was the main cause of evolution.(10) Although there are fierce debates on particular views, and work in evolutionary developmental biology appears to extend our knowledge on how variation is produced in important ways, modern evolutionary biologists agree that natural selection is the most important cause of evolution. Although Lamarckism may appear to be more psychologically and philosophically satisfying, it conflicts substantially with the observed facts. There are many examples of environmentally imposed physical changes that are never communicated to the sex cells of an animal, and hence, their offspring. For instance, cut off the tails of mice for generation after generation. Let only those mate that have cut-off tails. The mice offspring will still be born with tails. Take the practice of circumcision, the now widespread human practice of removing the outer covering of skin from a baby boy's penis. Although of religious origin, this practice is now routine in Western culture to prevent infection. Here, evolutionary biologists will argue, is a substantial physical change imposed by the environment that has a definite advantage for survival, yet no one has ever witnessed the birth of a male child already circumcised.
Lamarckians are not able to explain the "somehow" of a communication link between an acquired characteristic and the DNA of a parent's sex cells. The majority of microbiologists believe that the inheritance of an acquired characteristic based on the creation of new genes based on directions from the environment is a chemical impossibility, that information can pass in only one direction at the level of DNA. Coded messages can be sent from DNA via a chemical messenger to develop a particular physical characteristic, but not vice versa. Recall that developmental plasticity, different gene expressions, and epigenetic changes are also governed by genes.
Most important, Lamarck's theory is inconsistent with the paleontological evidence, the fossil record that indicates that the vast majority of species are extinct, implying a much messier view of evolution than that implied by the notion that acquired characteristics can be inherited just when they are needed. An amazing variety of forms of life have lived on this Earth. There are many different environments, and there are many different variations adaptable to these environments. Darwin's theory predicts a large amount of extinction; Lamarck's theory predicts very little extinction. For Lamarck, on the tree of life each tree branch is a ladder, where each lower animal simply changes to another higher form; Darwin's tree branches again and again with most of the branches coming to a dead end, dying and dropping off completely. The empirical match between the fossil record and Darwin's predictions is striking. Remember that theory must explain both the success and failure observed in the fossil record.
Although irrelevant to the factual evidence, originally Lamarckism was viewed as a compassionate theory of evolution, implying that some sort of higher power is guiding and protecting life. Darwinism was often seen as cruel and harsh; through massive amounts of death room is made for new creatures. But modern supporters of Darwin point out there is great wisdom in a natural mechanism that protects DNA most of the time from capricious change. Consider what would happen if every time the environment changed babies became different than their parents. There would be chaos in the development of life. In the giraffe case, what would have happened if there was a drought for only a few years? Because the environment remains stable overall for many centuries at a time, there is great wisdom in a natural mechanism that protects DNA from capricious change.
In 1996 Pope John Paul II reminded Catholics and the
of the world that accepting natural selection theory is
inconsistent with a faith in a supreme being.(11)
Believing in natural selection as a law of nature should
be no more
injurious to a religious faith than believing in the law
Recognizing that death makes way for new life seems no
acknowledging the fact that we all die to make way for
why would He not be a Darwinian?
What is intriguing about Lamarckism, and undoubtedly
the reasons for its staying power, is that it
scientific form, or at least attempts to, the major
objection mentioned earlier. Life appears to be too
to every environmental niche to be an accident. Human
superior to other creatures, we have conscious minds
that many have a
hard time believing can be reduced to mere physics and
Lamarckism implies that humankind is a superior end
evolution. When Darwin first proposed the theory of
the religiously minded rejected it out of hand as
impossible, not on
scientific grounds but on philosophical grounds. It
implied that the
Bible was wrong and that God, if He existed at all, was
Today new approaches have emerged that also reject the
Darwinian position and claim not only to be more
consistent with the
Bible but also to be better scientific theories.
We are afflicted with a government that has waged war all across the world to avenge the deaths of 3,000 terror victims, far fewer than die of influenza in a mild year; a government that insists on spending $50 billion to build a missile defense system that does not work . . . . We have grown so foolish and so incompetent that perhaps we do not deserve to survive. Ronald J. Glasser, MD
and Intelligent Design
These views have come to be known as scientific
and intelligent design. Proponents of scientific
creationism argue that
no evolution has taken place on Earth and all life was
the same time frame about 10,000 years ago, a time frame
shorter than that portrayed in standard geology
(approximately 5 billion years). Knowing perhaps that
the evidence is
overwhelming for an old Earth and universe, and that
acceptance of a
10,000 year old universe necessarily involves the
rejection of not just
basic biological science, but astronomy, geology,
chemistry as well, intelligent design promoters accept
most of the
standard geological dating -- the universe and the Earth
are very old
-- and even that there has been a lot of
species on Earth. (The basketball examples discussed
above would be an
example of microevolution; a completely different
species, such as a
human-giraffe-like creature, evolving from the tall
humans in the
culture would be an example of macroevolution.) They
that major species events and changes in animal
categories, such as
that from fish to land dwelling creatures, involve too
many elegant and
coordinated design changes to have been the product of
and unplanned process. Essentially those who
creationism are young-Earth creationists and those who
intelligent design are old-Earth creationists. Both
groups have lobbied
throughout the United States for equal treatment in
and biology classes. In a democracy should not students
be informed of
competing scientific theories?
For the most part, the argument of scientific creationism can be divided into two main categories: (1) attacks on the apparent weaknesses in natural selection theory and the general concept of evolution, and (2) a number of traditional philosophical arguments based mainly on rationalism.
In attacking what can be called the epistemological weaknesses of natural selection, creationists will argue that it requires a gigantic leap of faith to reconstruct evolutionary scenarios from the fossil record. A paleontologist or an evolutionary anthropologist will find a tooth and conclude from this tooth that the creature who possessed this tooth was an apelike creature, lived 7 million years ago, did not walk upright, and ate primarily fruit and course vegetation. Isn't this a bit much to conclude from just a tooth? As we have already noted, a fossil is the result of an extraordinary death. Do the fossils found thus far accurately represent the whole? Millions of fossils representing 250,000 species is a very small sample compared to the billions of species thought to have existed on Earth.
There are also acknowledged gaps in the fossil record.
Darwin noted that the fossil record does not seem to
show a gradual
evolution. And then there is the apparent biggest gap of
all, known by
Darwin's time, a gap from the time of the very first
about 4 billion years ago, to the Cambrian explosion,
about 580 million
years ago and the beginning of 99 percent of the
development on Earth. It is imagination that fills in
these gaps, not
evidence, so the creationists maintain. If the dates are
fossil record supports an abrupt beginning of all life
on Earth, one
consistent with a literal interpretation of the Bible
and creation by a
supreme being in a short amount of time.
may not be helpful, but the concealment of it
cannot be. Melvin Konner
The tale of (hominid
creationism’s worst nightmare …. the fossil record
of human evolution
is one of the very best, most complete, and ironclad
examples of evolutionary history that we have
assembled in …
. . . the little
contains so much of our connection to the rest of
life that it is
virtually impossible to understand our bodies
without knowing teeth. Niel Shubin, Your Inner Fish
|Is this argument a criticism of natural
selection theory and the concept of evolution or of the
scientific method? In Chapter 2 we learned that
intelligent inductive inference, and creativity always
fill in the gaps
in evidence. The major issue is always whether the
empirical evidence supports one conceivable picture better
another. Recall how little factual evidence was available
Eratosthenes. The history of science has demonstrated
the critical process inherent in the scientific method
allows a few
facts to go a long way.
Hyper critics of natural selection theory are essentially arguing that because we can’t find every single step – every single fossil that might indicate transitional forms – this theory must be false. But this criticism ignores the multitude of transitional fossils found (whale and horse ancestors, Tiktaalik, and hominids to name a few) and how all the other aspects of biology discussed above corroborate the fossil picture. After 150 years of steady accumulating pieces of a puzzle and predictions matched again and again by new evidence, all of which seem to clearly show the same picture, a reasonable person does not deny a highly probable picture just because not all the pieces are in place. Remember that predicting things we can see is the way of empirical science. Almost daily modern science confirms the predictions of evolution theory in biomedical science, genetics, embryology, and in paleontology. Thousands of species of dinosaurs have been found in the fossil record. If scientific creationism is true, then all the dinosaurs must be alive on Earth somewhere. Most scientific creationists say yes, they must be in Africa and some groups even arrange expensive search parties to prove that they are there. You can sign up today if you have enough money. These would be huge live creatures. Where are the pictures? Recall that Darwin made a much more difficult to find prediction -- fossils of ape-human-like creatures in Africa, and they were found.
Epistemologically, the status of the evidence for natural selection theory is no different than that of the cigarette smoking studies discussed in the previous chapter. In the case of the cigarette studies, a relatively small number of people have been sampled compared to the billions of people who have smoked cigarettes. In the case of evolution theory, if there were no questions raised by gaps in evidence, there would be nothing to discuss and debate, and there would be no room for further growth and understanding. All of the questions raised by the creationists were raised by scientists themselves long ago. Debates and discussions on evolution take place all the time, and more often than not, new ideas and levels of understanding emerge from these debates.
For many years scientists pondered the 3 1/2 billion year gap between the emergence of the first bacteria and the Cambrian explosion. Today we know that because the first bacteria were anaerobic -- oxygen is a poison and is excreted -- and because the primitive atmosphere of Earth had very little oxygen, billions of years were required for the oxygen level to build up in the atmosphere. This accumulation then allowed for both the creation of a protective ozone layer to screen out harmful ultraviolet light and a level of ordinary oxygen capable of sustaining the more familiar life on Earth today. Furthermore, the puzzling gaps in the fossil record have produced a suggested modification of an ultra slow gradualist interpretation of evolution, known technically as punctuated equilibrium. Rather than seeing the fossil record as incomplete, this view suggests we interpret the data in many cases literally: Evolution is marked by long periods of stability, punctuated by relatively rapid change. (Keep in mind that "rapid" for a geologist and paleontologist means hundreds of thousands of years.) If the environment of a particular niche is stable for a very long period of time, there would be no favorable selection of novel variations. According to this view, the life of any species is marked by "long periods of boredom and short periods of terror."
On the question of bone deductions and the
of fossils, scientists debate, critique, and discuss
interpretations constantly. See Figure
3-8. Teeth are harder than bone and fossilize
easily. We can
compare the difference between reptile and mammal teeth
today and see
how they differ remarkably. Reptile teeth, big and
small, all have a
blade-like shape. Ditto for the dinosaurs and other
reptiles. Mammalian teeth are diverse, functional for a
Sharp teeth in front for cutting, canine teeth in the
puncturing, and flatter teeth in the back of the mouth
Fossils have been found around the world of a small
creature that lived 150 million years ago. From its
(diverse with frontal incisors, middle canines, and back
molars) we can
intelligently infer that it was one of the first
Furthermore, the interpretation of what a tooth shows is the result of a cooperative community effort: Scientists trained in comparative anatomy will confirm that the tooth is indeed similar to that of present day ape; a physicist will take an electron microscope or a computerized tomographic picture of the tooth, revealing microscopic scratches and a pattern of wear identical to the teeth of fruit-and vegetable-eating animals living today; a geologist will analyze the rock strata and date it both by an analysis of the layers of rock and the radioactive elements in the rock; another geologist will confirm that millions of years ago the location's environment was a lush jungle similar to what apes live in today; a paleobotanist, a specialist in extinct plant biology, will analyze the plant fossils, even the fossilized pollen grains, to confirm the jungle plant life of the area; and so on. Could they all be wrong?
Yes. It is conceivable that the creature in question was a strange type of cow with a deformed tooth, or that the creature was indeed apelike, and this particular one had developed a bad habit of chewing on sticks. Or perhaps a hurricane blew the tooth, the pollen grains, and the remains of plant life many hundreds of miles and deposited them in the middle of a desert. Many scenarios are conceivable, just as it is conceivable that the cause of lung cancer is not cigarette smoking, but exposure to a strange chemical substance that activated a virus many years later. The question is which of all the possible scenarios is the most reasonable. Inductive evidence is always incomplete; the conclusions always go beyond the evidence. The constant challenge is to make the most intelligible inferences, to be able to separate the most reasonable view from all the conceivable ones.
The evolutionary scenarios that scientists have put together could conceivably be wrong, but they are not "gigantic leaps of faith." It is hardly epistemologically fair to criticize the theory of natural selection and the concept of evolution on the basis of the problem of induction, a generic challenge for all science, and then conclude there is a more scientific approach. For the most part, the only thing scientific about this aspect of creationism is the willingness to now discuss some of the empirical evidence, rather than object to evolution on philosophical grounds alone.
order and the beauty of the universe compel me
to admit that
there is some excellent and eternal Being, who
deserves the respect and
homage of men. Cicero
much time, the "impossible" becomes possible,
the possible probable,
and the probable virtually certain. One has only
to wait: time itself
performs miracles. George Wald
The brain is] an enchanted loom where millions of flashing shuttles weave a dissolving pattern. Sir Charles Sherrington
Creationists often refer to the theory of evolution as an "animal fairy tale." Objective observations and a little common sense, they say, show it is more logical to believe that God purposely created all at once the beautiful adaptations that we see today. Although denying all-at-once creation, intelligent design supporters are essentially advocating the existence of a serial creator who steps in again and again to create distinct species. We can see microevolution, but the final creative jump from a pre-Okapi to a giraffe must have had some supernatural design help. It is just more logical than an undirected and unplanned process. The phrase "more logical" might, however, only mean what seems more comfortable.
A major argument of the creationist is actually some borrowed philosophical reasoning called the design argument. This argument proposes that it is much more reasonable to assume that the adaptable intricacies of nature were designed and could not possibly be the result of accident and chance. Consider just a few of nature's art works.
In South America there is a moth that spreads its wings to scare predators away. When it spreads its wings, it reveals a design that looks very much like a ferocious monkey. There is also a passion fruit vine that is covered with yellow spots strategically placed on tender new shoots. To a butterfly looking for a place to deposit its eggs -- eggs that would turn into worms and eat the leaves -- the yellow spots look like some other butterfly has already staked out this territory. Because it is disadvantageous for the butterfly to lay its eggs where others already exist, it looks for a better place to reproduce. Also in South America, there is a ventriloquist lizard, which is capable of throwing its voice, making it seem to a predator looking for a meal that the sounds of the lizard are originating in another location. Could these marvelous adaptations be accidents?
Consider also that there are insects that can withstand incredibly low temperatures because they have antifreeze in their blood (Figure 3-9); four-eyed fish, two eyes to see out of the water and two eyes for seeing under water simultaneously (Figure 3-10); fish with flashlight eyes containing phosphorescent bacteria to see in the dark depths of the ocean; a bottom-feeding shark that looks like a rock; flowers that stink to attract flies and ensure pollination; fish, frogs, and squirrels that fly (glide); a "Jesus lizard" (Figure 3-11) that can run across lakes and streams; and the Panda with a sixth finger (a thumblike appendage) that enables it to eat bamboo shoots. Finally, consider the monarch butterfly and its color. The monarch's orange hues are a message to predators (especially birds) that sickness and possibly death from deadly toxins will result if the butterfly is used for a meal. Consider also that this same sequence of colors is seen in such diverse creatures as snakes, frogs, birds, and even sea slugs with the same warning implied. (Figure 3-12)
Is it not much more reasonable to assume that such unique features are the result of intelligent design? How could an anglerfish (Figure 3-13) develop a little fishing pole by accident, one complete with a little fish-like appendage of bait at the end? How could an insect develop antifreeze in its blood? How could such things develop by chance?
The design argument usually employs the following analogy. Suppose you were shipwrecked on an apparently deserted island. Your ship had been blown off course by a violent storm -- so far off course that the island was not on any map you had ever seen. There was, at first, no sign of human life, past or present. One day, while walking along the beach, you found a wristwatch. Which would be more reasonable to conclude? (1) That nature, through a process of a number of coincidental events, had produced the watch; that bolts of lightning had somehow struck various rocks and produced at various times pieces of metal and glass, which just happened to be the intricate parts of a watch; that the wind just happened to assemble these pieces and they all just happened to fit! Or (2) that somewhere, at some time, an intelligent human designer crafted the watch, and it somehow ended up on the beach. Surely, even if we allow for a time span of millions and millions of years, it is much more reasonable to conclude that the watch is the result of the craftsmanship of an intelligent creature, capable of purposeful planning.
The physical universe and any life form are much more intricate and complicated than a simple watch, so the argument goes. Which is more reasonable then: that this is all the result of blind chance, or that it all has been crafted by an intelligent being? Could moths just happen to grow monkey faces on their wings? If all things are possible, why didn't the little fishing pole of the anglerfish develop backward, away from the fish's mouth? Is it merely a coincidence that it faces forward so that the fish can catch a meal? Or, consider a type of sea slug that lives off the Great Barrier Reef. It eats stinging jellyfish. The stinging cells of the jelly fish do not affect the sea slug, instead the slug uses the cells for its own protection. After the jelly fish is consumed, the stinging cells are not digested, but migrate intact to the back of the sea slug. Here they offer formidable protection from any animal wishing to make the sea slug a meal. Is it not just as unlikely that such coordination is the result of chance as lightning producing the parts of a watch?
ridiculous to make evolution the enemy of God.
What could be more elegant, more simple, more
brilliant, more economical, more creative,
indeed more divine than a planet with millions
of life forms, distinct and yet interactive, all
ultimately derived from accumulated variations
in a single double-stranded molecule, pliable
and fecund enough to give us mollusks and mice,
Newton and Einstein. Charles Krauthammer
science class one is professionally and ethically
obligated to teach the best theories and our most
|Consider also the amazing complexity of a
human being. The human body consists of trillions of
cells. In each
cell there is a nucleus and DNA. It is estimated that
human DNA has
about 30,000 genes. It is because of the genes that heart
coordinate their activities to pump blood, that pancreas
insulin, that hair cells form hair, that fertilized egg
and become babies, and that thousands of other things
essential to life
occur. That eyes see and brains think is the result of a
more complicated than a watch. It could not have happened
so the authors of the design argument argue. There must
Aspects of this argument have appealed to many intelligent men and women through the ages, not just to the philosophically and religiously minded, but to great scientists as well. From the very beginnings of Western culture, the roots of the scientific outlook have been infused with a sense of wonder at the marvelous order around us. Many great scientists have been impressed not only by the ecological beauty of the biological world but also by the apparent mathematical harmony that can be found everywhere one looks in the physical world.
We must be careful, however, with our sense of order, logic, and reasonableness. If we are sincerely interested in the truth, we must consider where our sense of order might be coming from. Could it be more of a projection of the workings of the human mind than an actual independent reality? Might not our inability to fathom how an insect could end up with antifreeze in its blood be more of a reflection of the limitations of our imagination, especially the difficulty of maintaining a sense of the vast amount of time that has elapsed on Earth, and the many possibilities that could take place compared to our short life spans?
The eighteenth-century British philosopher David Hume was the first to point out the following argument. Let us assume for a moment that our observational experience of nature does indeed point clearly to a creator, a master craftsman of all the intricate beauty around us. The fact that we now know that a creator exists does not tell us much about the important characteristics of this creator. How would we know that this creator is good, all powerful, all knowing, and eternal? How would we know that the human species is a special creature in the grand scheme of things? There is also a great deal of suffering and chaos in the world. The data are consistent with not only a good God, but an evil one as well, a sadist, a bungler, whose "watch" sometimes falters or is used for evil purposes. If we are to be honest about the watch analogy, the fact that we find a watch on a beach would only indicate that a finite craftsman existed somewhere, a creature who lives and dies, sometimes does not get along with others, and has a potential for good or evil. For all we know, our master craftsman could be a temperamental artist capable of great art, but not at all a nice person to be around.
Hume's point is that the argument from design is logically invalid, if one attempts to infer a God with all the Judeo-Christian qualities from the observation that nature has apparent design features. The argument needs to be supplemented by a great deal of faith in the Bible. Additional premises would need to be added about the life of Jesus, his mission, and his claimed resurrection. We would need to discuss the evidence that the Bible was divinely inspired and the epistemological issue of whether revelation is a valid means of gaining knowledge. These are not silly issues and should be discussed in a democratic society. They are not, however, ideas that need to be discussed in a biology class.
Furthermore, it does not prove much to say the universe has to be ordered in some way or it would not work. Could a universe work that was not ordered in some way? If the anglerfish had grown its little fishing pole the wrong way, it would die. If insects in frigid climates did not have some kind of antifreeze in their blood, they would not be around for us to wonder about. The fossil record shows that many exotic animals have existed, that natural selection has experimented with many different designs, and that most of these designs survived and reproduced for a time, but when the environment changed their time was up.
Observational experience, of both human and animal life, demonstrates that mutations and copy mistakes in DNA occur regularly, but for the most part these changes are detrimental. The apparent design we see today is the result of a relentless rolling of the dice and a vast amount of death, albeit within tool kits of channeling.(12) Observational experience shows a messiness to evolution that is best accounted for so far by the theory of natural selection. Sickle-cell anemia is a valuable characteristic in one environment and a debilitating disease in another. Recall also that we can see the fossil genes for the blood of the icefish ancestors, smell for whales and dolphins, and that for our Vitamin C producing ancestors. If God has decided to be a serial creator rather then just use a simple but brilliant law of nature to create life, why would He leave faulty parts in new creatures that formally worked in older creatures? Natural selection theory accounts for the messiness and both the adaptive success and the adaptive failure that we see.
of intelligent design theory will argue that fossil record
Nature is not always elegant from a human point of view. The sea cucumber has a rather ugly way of defending itself. If a fish or crab gets too close, it defecates its internal organs leaving the surprised predator entangled in a sticky mess. The sea cucumber remains alive and grows back its intestines in a few weeks.
For so-called scientific creationism, consider also that if each species was created to perfectly match its initial local environment by a designer, such a designer would be neither intelligent nor compassionate, given that environments change and initial designs would then fail. Over the centuries continental plates move, the Earth's rate of spin changes, the sun expands, the amount of carbon dioxide in the atmosphere fluctuates, ice ages, El Ninos and La Ninas come and go. Why would a wise and benevolent God not choose some mechanism of adaptive change for His creatures? Why would He not be a Darwinian?
the human imagination to grasp certain crucial
features of reality
is a warning that we cannot expect to base great
religious truths ...
on simple-minded ideas of space, time, and
matter, gleaned from daily
experience. Paul Davies
The current scientific
picture of the universe places humans in a very
humble perspective, and
humility and appreciation toward a foreboding power
that has given us
life and can take it away in an instant are values
consistent with all
the world's major religions.
Another argument borrowed by the creationists is known as the cosmological argument. Is it conceivable that the universe could have been created from nothing? Or that the universe is here for no reason? Is it not more reasonable to believe that there is a purpose to all that exists rather than absolutely no purpose? Because natural selection implies that there is no direction or purpose to life, and it is more logical to believe that there is a purpose to the universe, natural selection must be false.
Proponents of the cosmological argument claim that the universe had to have a beginning, otherwise it is eternal with an infinite amount of time behind us and an infinite amount before us. An infinite universe, it is argued, is impossible because we cannot then explain why we are here now rather than at some other time. So assuming the universe had a beginning, could it have arisen from nothing, without a cause, and for no reason? If our universe was created as part of some megaprocess within a multiverse, what caused the multiverse? At some point we have to stop. Conclusion: it is much more logical to believe that the universe had to have a first cause that itself was not caused (God) and the universe has to have a story, a plan, or purpose. Nothing happens without a reason, so surely the whole universe or multiverse could not happen without a reason.
The first point to note about this argument is that part of it is purely rational, and science rejects rationalism as a valid method for achieving knowledge. Better is to argue empirically that because we have witnessed no event that was without a cause (actually this may not be true, see Chapter 8), it is probable that the universe had a cause. But this conclusion, even if well supported, has little to do with refuting natural selection theory. Natural selection is a theory about the development of life in the universe and makes no statement about the origin of the universe. Clearly, scientific creationists use these arguments because they believe that one can refute natural selection theory if one can prove God exists. It is possible, however, to believe that God exists and natural selection is one of God's laws of nature, just as there is no inconsistency in believing in the law of gravity and God.
Scientific creationists reject this possibility
the notion of purpose. An old and vast universe that is
not seem to fit the story that the universe was planned
just for us.
Humans appear to be an accident and an afterthought of
years of contingency. That the universe existed for
billions of years
before we could presumably take center stage seems to be
with the story that we are important and the main focus
However, supporters of natural selection theory and a
belief in God
respond that we should not be too quick to judge God's
current scientific picture of the universe places humans
in a very
humble perspective, and humility and appreciation toward
power that has given us life and can take it away in an
values consistent with all the world's major religions.
humans die to make room for new humans and few see this
as an example
of divine bungling. So why should we be upset or
evolution might also be part of God's plan when we
millions of species have had their day in the sun but
have perished to
make room for new species? As Darwin noted, there may
well be grandeur
in this view of life. And the Bible clearly
importance of the same contingency that plays such a
major role in
natural selection theory.
returned, and saw under the sun, that the race is not to
the swift, nor
the battle to the strong . . . but time and chance
happeneth to them
In short, it is a mistake to think that natural selection theory is inconsistent with a religious conception of life.
It is difficult for human beings to imagine a universe emerging from pure nothingness. Advances in science, however, have repeatedly taught us that a failure of human imagination to grasp or make sense of a possible reality is more indicative of a clash between the truth and our common sense, rather than a proof that our common conceptions of space and time are more logical. It is also very difficult for a human being to imagine what the world looks like to an insect using ultraviolet light rather than the visible spectrum, or what a tree would look like in infrared light only. Yet we know that both of these perspectives exist.
Science has demonstrated that our common sense is based upon a built in perceptual filtering system, valid for our existence, but only a thin slice of all the possible windows to reality. Using the powerful tool of abstract mathematics, science has been able, again and again, to point to unimaginable realities. The Big Bang theory, which involves a mathematical description of matter, space, and time emerging from a single point from "nowhere" and "nowhen," is no longer thought of as unusual in modern physics. As we have seen, this theory is so well accepted that large sums of money have been spent on creating laboratories the size of small cities to understand the details. As Paul Davies has pointed out in his book, God and the New Physics, "Failure of the human imagination to grasp certain crucial features of reality is a warning that we cannot expect to base great religious truths (such as the nature of the creation) on simple-minded ideas of space, time and matter, gleaned from daily experience."(13)
A truly exalted being, if it exists, would create a universe where we are truly free to choose . . . We would then be required to do unto others as we would want them to do unto us, not out of fear of punishment, but because we have decided that it is the right thing to do.
|The universe as a single point? With space
time inside? But what is outside the point? Do not space
and time have
to be outside the point? And what would a multiverse be
"in"? Our minds
balk. It is impossible for humans to picture a point
being in space and time. For scientists during the time of
this was also inconceivable even mathematically, but for
Albert Einstein it is not only conceivable mathematically,
demonstrates it is reasonable. At the end of the Middle
Ages there were
many intelligent people who understood the mathematical
the Sun being the center of our system of planets and the
the Earth. But they rejected these ideas because of the
a huge, unimaginable space between the Earth and the
stars. So much
space was inconceivable. Today, the empirical support for
the Big Bang
theory undermines much of the intuitive force of the
argument. If it is conceivable that the entire Universe
from a single point, then there is a possible natural
the universe emerging from a kind of nothingness. These
theories are not just something scientists have made up,
but the result
of a long struggle, being the best explanations that we
have for modern
But what about the intuitive feeling that there must be a purpose for the universe; that there must be a reason why there is something rather than nothing? Many scientists, after all the natural explanations have been stated, have stood back from their equations and technical data and have been swept away emotionally by the wonder of it all. Any sensitive human being should be able to experience this same feeling by simply immersing himself or herself in a dark starlit night and contemplating the fact that the points of light one sees are trillions of miles away. Why is all this here rather than not here?
It is admirable that human beings have this emotion. Einstein argued that a human being who was incapable of having this emotion was as good as dead. Einstein also argued that science has not destroyed this emotion, it has enhanced it. Scientists are no different from the rest of humanity. Few, however, would be willing to assert that there is a scientific connection between this feeling and the existence of a particular conception of God, or that this feeling proves that there is a better scientific explanation for life than natural selection. However, a full understanding on the mechanism of natural selection and what it can create is perfectly consistent with what the Zen Buddhist scholar D.T. Suzuki called the “living fact of all religions” – awe, humility, and an appreciation for the immediate experience of living. For some, in fact, if anything at all can be made of this feeling, it makes more sense to believe natural selection as being more consistent with a truly glorious God. If there is no direction, purpose, or value system easily revealed by studying nature, this then places a much greater responsibility on each human being to make authentic decisions about right and wrong. A truly exalted being, if it exists, would create a universe where we are truly free to choose. There would be no obvious purpose so that we would be responsible for creating our own. We would then be required to do unto others as we would want them to do unto us, not out of fear of punishment, but because we have decided that it is the right thing to do.
If God indeed exists, then one of his greatest gifts to us was our reason. To deny science -- to deny evolution -- is not to be truly religious or truly moral. It is indeed the opposite. There is nothing in modern evolutionary theory which stands in the way of a deep sense of religion or of a morally worthwhile life. Michael Ruse
But how do we know what is the right thing to do? Consider the following situation. Suppose you are in a car alone, driving on an isolated road, far from any town or houses. It is a stormy night with rain and lightning, thunder and wind. The road is bordered by tall trees, and the wind is breaking off large branches. The lightning occasionally strikes close by. You feel relatively secure, however, because your car has plenty of gas, is well made, and has good tires. You have only a short way to go to connect with a much safer road, so the one thing you do not want to do is stop. Suddenly, just ahead, on the side of the road, you see two young children. One is about five years old and the other is only three. They are both drenched from the heavy rain and very scared. They are holding hands and crying, but the five year old is trying to be very brave as he pulls the three year old along. At any moment a large falling tree branch could crush them. What would you do? Would you stop? What is the right thing to do? How would you judge the person in a similar situation who does not stop, who concludes that they are not his children, and that whatever their reason for being alone in this isolated and dangerous place is none of his business?
Creationists will argue that any normal human being will know what to do, and the only way that we can account for this knowledge and the rightness of caring for children in situations such as these is that there is a moral sentiment and conscience given to every human being by a higher Being; a moral sentiment that reflects an absolute set of values revealed to us by this Being. In the purposeless, directionless universe of natural selection, there would be no motivation and sanction for such acts. Some people would stop and some would not, but without a God there would be no motivation to stop and no objective criterion for deciding the rightness or wrongness of stopping. Because good people exist that help children all the time, and we know intuitively they are right in what they do, God must exist.
As in the case of the cosmological argument, the creationist's argument again takes aim at engaging our intuition. There is a very strong feeling that stopping to help these children is the right response. This feeling is so strong that it is impossible to reconcile with the explanation that we have such a feeling only because of our cultural conditioning. The sense of rightness here makes the way a person was brought up, or the cultural background, irrelevant. There might be an explanation for why a person did not stop (poor childhood for example), and we might even understand in some intellectual sense why a person did not stop, but not stopping would still be wrong.
||We possess then, argue the creationists, an
innate potential for a strong internal sense of moral
sentiment -- a
sense of empathy and compassion for others that could lead
inconsistent with our personal well-being -- plus a strong
sense of right judgment. In other words, human beings
potential to develop and express a higher set of values, a
that can be termed other-directed: altruism and values
such as a
concern for universal justice, charity, and love. How
sentiments be possible in a purposeless universe of blind
the goal of evolution is individual survival and
how can we account for the intuitive feeling that acts of
and love convey a sense of universal rightness that seem
the physical dimensions of space and time? Or how can
account for apparent crazy acts of altruism?
In 1985 millions of TV viewers around the world were able to witness first hand a tragic fire at a British soccer stadium. Only minutes after the fire started, the heat from the fire had become so intense that the clothing and hair of people in the middle of the soccer field, a considerable distance away from the burning stands, began to burst into flames. With the TV announcer moaning "Oh look at this," the cameras showed a man in a daze walking slowly across the field, his hair and clothes ablaze. Suddenly, with little thought for their personal safety, people turned back running to the man and removing their jackets. They threw the man to the ground and attempted to smother the flames as quickly as possible. The heat was so intense where they were, that at any moment their own clothing could burst into flames. As the flames engulfing the man continued to resist extinction -- even some of the jackets used to smother the flames began to burn -- more and more people returned, ripping their jackets off and surrounding the man.(14)
Such actions are almost always spontaneous and noncognitive. That is, acts of altruism do not result from a carefully thought out cost benefit analysis as to what the individual may gain or lose, what dangers exist to one's personal well-being. From the standpoint of individual survival acts of altruism are irrational. If the driving force for evolution is individual survival and reproductive success, what possible reason exists for risking one's life for a complete stranger?
Because of considerations such as these, creationists
even the great British naturalist, Alfred Russell
co-originator with Darwin of the theory of natural
to apply this theory completely to the evolution of the
There is, thought Wallace, such an obvious moral
the valueless world implied by natural selection and the
moral sensibility of humans, that God must have stepped
in and supplied
humans with a soul. For the creationist, Wallace's
inconsistency is a
symptom of the major problem the theory of natural
selection has in
explaining meaning in life and humankind's potential for
must not be forgotten that although
a high standard of morality gives a slight or no
advantage to each
individual man and his children over the other
men of the same tribe,
yet an advancement in the standard of morality
will certainly give an
immense advantage to one tribe over
another. Charles Darwin
only exceptionally, as in wolves and humans, that the
male plays an
important role in the protection and care of the
mother and child. E.
Peter Volpe and Peter A. Rosenbaum,
|The Evolution of Emotion (See
There are three possible responses to the creationist's argument. First, the intuitive sense of the rightness of certain values and actions could be a cultural illusion. Relativism holds that a distinction between right and wrong is simply a matter of cultural conditioning; that what is right in one society may not be right in another. Proponents of this view argue that this applies not only to matters of taste, such as food and clothing, but also to how to treat children. In another culture it might be appropriate to keep on driving, because this would "toughen up" the children, and it would be bad for anyone to interfere with this process.
Second, one could argue that stopping is indeed the right thing to do, but an appeal to God and a sense of universal purpose are unnecessary. Such actions can be given a purely rational basis. Insofar as human beings are rational animals, we can learn that actions of compassion and actions based on other higher values are the most pragmatic in the long run. Just as we are capable of a greater understanding of the natural world, so we are capable of learning a rational value system to guide the most practical and reliable way to live.
Whether or not moral values have an absolute (God-provided) or rational (human-provided) basis, or whether or not values are objective or subjective are very important issues in contemporary philosophy. However, more appropriate for a discussion on evolution theory, and this is the third response, is whether or not the theory of natural selection can account for human feelings of compassion and apparent acts of altruistic behavior.
Supporters of Darwin will note that acts of altruism in general, and acts of emotional bonding in particular, are not exclusively human behaviors. There are many examples of individual sacrifice in the animal world. There is not only the well-known action of a mother bird drawing attention to herself to save her offspring, but there are examples where the individual sacrifices itself for the good of the species and in some cases even other species. The field of study that compares animal and human behavior is ethology. Since the time of Darwin, ethological studies have been combined with natural selection theory to produce a remarkable scientific explanation for the evolution of emotion and human values.
Until approximately 60 million years ago, the primary reproductive strategy on Earth, as exhibited by insects, plants, fish, amphibians, and most reptiles, was for the female of the species to produce as many seeds, eggs, and offspring as physically possible. In this way, although most would die, a few would survive to continue the genetic line. Using this strategy, there was no need for much of a relationship between the parents and offspring. With few exceptions(15) the pattern continues for these groups: The parents completely remove themselves from any responsibility of care, and the offspring are on their own in the game of survival. For this practice to be successful, the offspring must emerge in a biologically mature form ready for survival, complete with instinctual behavioral patterns for gathering food and defending themselves against predators. There is little time for significant biological development and learning after birth.
With the evolution of the mammals, a revolution in reproductive strategy took place. Instead of the expensive production of many eggs, only a relative few are produced. For this to work, a motivation to stay around for the developing offspring must exist, and the parents must display a large investment of protective time. Thus, on a heretofore, for the most part, uncaring Earth an emotional bond became common between mothers and their offspring.(16) From this point, adopting a very broad perspective on the evolution of mammals and the human species, one can see a pattern of generalization of what might be called "companion feeling" emerging with time and circumstance.
At first there is only maternal love. For the male of many early mammalian species, the old pattern is still workable. They do not stick around to care for their offspring, and their time is much better spent finding and mating with as many partners as possible. Eventually though, a new strategy emerges, a mini-revolution within a revolution: paternal love and the family. Just as it was useful to invest a large amount of time on a few offspring rather than to waste that same energy producing many that would die, so we find that it is expedient for the males to invest their time partaking of a protective family arrangement, strengthening the probability of the survival of their offspring. Given the proper environment, not only is this arrangement an advantage in terms of efficiency, but it also increases the probability that the male will find a mate, because females have begun to select mates on the basis of whether or not they will stay around and help with child care.
An additional functional relationship is the clan or herd. Just as it is a personal advantage for the mother to care for her offspring (so part of her genes will survive), so it is a personal advantage to care about the members of one's extended family and eventually even unrelated members of one's own species. The more the species prospers, the more likely one's offspring will prosper. By the time we reach the human species and human civilization, forms of companion feeling have become potentially very abstract. Why should I risk personal injury for strangers? Why should I care about children that are not mine? Because my own children have a much better chance of survival in a world where people do such things.(17)
Finally, although an ecological consciousness can hardly be attributed to contemporary humans alone, today we see an ever increasing concern for the well-being of the entire natural environment. Some have called this biophilia, literally "love of the biosphere." We are learning that our Earth is a fragile, contingent place, and the smallest disruption to the smallest creature can have major consequences to all life on Earth. From the standpoint of evolutionary biology, however, this awareness is not totally one of learning. The instinctual potential to touch the world sparingly has its roots in the relationship of companion feeling between the mammalian mother and baby. In general, we find ourselves reacting positively and protectively, not only to babylike features within our own species, but to the puppylike and juvenile features of other species as well.
In contrast to the engineer ... evolution proceeds like a tinkerer .... in contrast with the engineer, the tinkerer who wants to refine his work will often add new structures to the old ones rather than replace them .... [In the brain of mammals] it is somewhat like adding a jet engine to an old horse cart. No wonder accidents occur. Francois Jacob
|Although much debated, this
ethological-evolutionary explanation for the development
of the human
potential for higher values is an intriguing possibility
philosophical ramifications. Suppose love is an accident,
a result of a
fortuitous change in reproductive strategy? Should it be
In support of this explanation, there is a subfield of ethology called neuroethology, the comparative study of the physiology of the brains and behavior patterns of different animals. One result is the theory of the "triune brain," authored by Paul MacLean.(18) Although judged to be somewhat oversimplified today, it is maintained that human beings and other recently evolved mammals show in their brains at least three major evolutionary steps. At the base of the human brain is a neurological structure known as the R-complex. The "R" is for "reptilian brain." Whether in reptiles, birds, or mammals, this structure is concerned with controlling instinctive behavior patterns that are routine and fixed, especially those related to self-preservation, such as aggression related to defense of territory. On top of the R-complex is the "old mammalian brain," referred to more commonly today as the "limbic system." It is this structure that is associated with emotion. In the light of the discussion above on reproductive strategies of reptiles and mammals, it is significant that this neurological structure is found in mammals. Finally, on top of the old mammalian brain, in human beings, primates and other recently evolved mammals such as whales and dolphins, there is the cerebral cortex---the site of advanced information processing and learning.
A female Hamster that has its cortex removed at birth will develop almost normally, able to carry out all the basic routines of food gathering, defense, and reproduction. She will even be capable of being a mother. Only the precision of her behavior seems to be affected. But further removal of the limbic system damages maternal and play behavior significantly. In human beings with Parkinson's disease and Huntington's chorea there is often a partial or total inability to initiate and carry out routines. In one well known case, a woman who could consciously decide that she should start dinner found herself incapable of carrying out this routine task. As would be expected, such diseases have been traced to defects in the R-complex.
Thus, the neurological structures in animals and humans can be roughly correlated with general behavior patterns. Although there are major exceptions (birds and dinosaurs), in general, non-mammalian creatures lay many eggs and do not care for their young, thus necessitating immediate, instinctual routines necessary for survival. Mammals lay few eggs and care for their young, allowing for slow development and learning, and requiring a neurological structure, not only to mediate an emotional response to the world, but to process the complexities of child rearing as well. At least on Earth, emotion is associated with bigger brains, slower development to adulthood, and greater awareness and learning.
who call themselves pessimists because they
cannot read good into
the operations of nature forget that they cannot
read evil. In morals
the law of competition no more justifies
personal, official, or
national selfishness or brutality than the law
of gravitation justifies
the shooting of a bird. Vernon Kellogg
Natural selection theory can explain human motivation for altruism and our potential for a caring value system. It cannot, however, justify (sanction) in an absolute moral sense why we feel it is better to have a mammalian rather than a fish reproductive strategy. From a Darwinian perspective both strategies work in the game of survival. Cockroaches have lived on this planet far longer than humans and they do not take care of their offspring. Horrifying to human families, competitive infanticide is not uncommon, even in primates. Hanuman langurs live in groups with a single male mating with several females. A male from outside the group can attack the dominant male. If he wins, he will immediately kill all the infants under six months old so the mothers will go back into heat and soon produce offspring from the invading male.
The fact that there may be a natural explanation for particular human behaviors does not prove that these behaviors are the best or are right. Most evolutionary psychologists also believe that the human male is biologically programmed to have a much greater potential for infidelity than the human female. But having this belief about a fact of nature does not mean that evolutionary biologists are endorsing male promiscuity as moral behavior or that the behavior is inevitable. Genes and evolutionary history are not destiny. A propensity for infidelity is mixed with one for family bonding, and humans in general are a messy mix of instincts for competition and cooperation. The theory of natural selection is not a moral theory; it is a scientific theory that explains the development of life on Earth. Evolutionary psychology is also a scientific theory that claims that the history of our biological development is very relevant for understanding why we behave as we do. Evolutionary psychologists take the position that if we do not like some of the behaviors we see exhibited by humans (infidelity, violence, exploitation), and we desire to change those behaviors, then we should know what kind of causative factors we are up against -- what in the history of our biological development has produced these behaviors and what environmental factors might set them off. Similarly, for behaviors we believe are good, to promote those behaviors we should know their underlying causes.(19)
Both competition and cooperation are observed in nature. Natural selection is neither egotistic nor altruistic. It is, rather, opportunistic. Theodosius Dobzhansky
|The creationists are not interested in what
goes on in a person's brain when compassion is
experienced. They want
our lives to have meaning and direction. They want a
perspective that says there is a difference between being
kind or cruel
to a child. On this point, supporters of natural selection
creationism agree: natural selection theory does not
one moral theory over another. But this has nothing to do
natural selection theory is true. Natural selection
could be true
and it could be one of God's laws of nature. Natural
could be true, and God may not exist. If God exists,
He may give
each person a soul at birth, as Catholics (who accept
as the best scientific theory for evolution of the human
or He could have given the human species the ability to
values to go along with our freedom. But these are
that, as important as they are, go beyond the realm of
Of the few things that philosophers agree on, most agree that it is not possible to logically (deductively) connect "what ought to be the case" with "what is the case." To think otherwise is to commit the naturalistic fallacy. From the standpoint of natural selection, the mammalian reproductive strategy, which serves as the basis for the development of emotion and companion feeling, is just another successful strategy, an efficient adaptation given the proper environment. If there is no direction and purpose in evolution, then the mammalian strategy is not necessarily better. From descriptions of reproduction strategies alone, a morality cannot be derived logically. In birds, for instance, there are both monogamous and polygamous species. For species whose food source is abundant it is not necessary for the males to help rear the young. It is also a relative disadvantage for more than one parent to frequent the nest. It calls too much attention to the nest. Natural selection does not sanction one value system as better than another. The system that works well for one species may not work well for another.
a biological accident or part of God's plan, the
potential to act
morally exists. Do
we need to
justify these values, or choose them? Sometimes
care for our children and sometimes we do not. Our
awareness of our
messy evolutionary background can not only help us
understand why, but
also help us choose who we want to be.
||But is it necessary to prove deductively
humankind's so-called higher value system is better? As in
the cases of
the other arguments for the existence of a God-like
purpose in the
natural world, an appeal to an intuitive sense of
rightness of human
action could well be more of an indication of
anthropocentrism than a
crucial proof that something is wrong with a particular
evolution. Natural selection provides an explanation for
how it is
possible for human beings to base some of their behavior
values. This explanation is not inconsistent with a belief
God. Natural selection theory can also account for
values are possible in a directionless universe.
Again, God could
exist and be a Darwinian.
Evolution theory may not be able to account for the rightness of such behaviors in an absolute sense, but this demand is unnecessary in the first place. Whether a biological accident or part of God's plan, the potential to act altruistically and other-directedly exists.(20) Do we need to justify these values, or choose them? Like our very existence, our potential for higher values may be a result of happenstance. Natural selection is messy, and this is reflected in the fact that human beings are morally messy. Sometimes we care for our children and sometimes we do not. Our awareness of our messy evolutionary background can help us choose who we want to be.
issues raised by the creationists are important, but they
scientific issues. The design, cosmological, and moral
all traditional philosophical arguments that are primarily
methodological orientation rather than empirical.
objections raised by the creationists against evolution
primarily of attacking the apparent weaknesses of the
than directly supporting creationism with empirical
evidence. It is a
basic epistemological tenet of science that extraordinary
require extraordinary evidence. It is an extraordinary claim
species of life on Earth was designed and created all at
once by a
benevolent intelligent higher being or that this being
is a serial
creator. As such,
to gain the title of a scientific hypothesis, these
views must be
refutable and have direct empirical evidence for them.
What kind of empirical evidence can confirm supernatural
connections to established scientific fact are not
There is no comparison between the successful
of evolution theory fulfilled
almost daily and predictions from the Creationists, such
dinosaurs still alive and hiding somewhere in Africa.
the geological and astronomical evidence that the
universe is only 10,000 years old? To
reject the Darwinian evolutionary story for producing
life on this
planet and accept such a belief, one must reject
(biogeography, embryology, morphology, genomics and
genetics, biochemistry, molecular biology, and
chemistry, geology, and physics. Those who
question the massive,
corroborative inductive reasoning supporting Darwin's
basic ideas on
evolution are like those who would spend a paranoid
amount of time
thinking (Chapter 2) of all the possibilities for the
100th apple in
the thus-far thoroughly rotten barrel not to be rotten,
or that science
has not yet ruled out absolutely that exposure to a
strange chemical on
the third birthday of all lung cancer victims might be
the real cause
of lung cancer. Given the alternatives to Darwin's
view is remotely close to matching the empirical
Logically, the argument of the so-called scientific creationists can be reduced to a questionable dilemma fallacy. They have given us only two choices: either natural selection is true or creationism is true; intuitively something feels wrong about natural selection theory and there are epistemological problems in terms of it being "totally" certain; thus, creationism must be true. But aside from other theories of evolution, there are many other views of creation. Old-Earth serial creationists (supporters of intelligent design) acknowledge the basic truths of astronomy and geology. But this view does not match the empirical facts of success and failure seen in the fossil record. Why would an intelligent serial creator produce a newly designed watch by leaving all the broken pieces of previous designs inside? Even if it could be demonstrated that something is seriously wrong with the Darwinian theory of natural selection, it would not follow that science has thus proved that a traditional Western religious conception of God and creation is true, or that there is direct evidence for a designed creation of every species on Earth.
Scientists have opposed vigorously the teaching of
creationism and intelligent design alongside natural
in the science classes of public schools. Such
opposition is often
portrayed as dogmatic by supporters of creationism and
design. In a democracy should we not introduce children
to both views?
Of course, scientists will respond, perhaps in religion
classes, but in a science class one is professionally
obligated to teach the best theories and our most
It would be morally and professionally irresponsible for
a physicist to
teach children that there is an evidential, equal
alternative to the
law of gravity and that they might be able to fly from
Similarly, it would be morally and professionally
irresponsible for a
biologist to teach children that creationism is equal in
natural selection. The consequences are enormous. A
ignores a law of nature such as gravity will make
A society that ignores the message of natural selection
is not likely
(There is) the misconception that we no longer need concern ourselves with the welfare of our fellow citizens. It is a dangerous conceit, and it leads us toward a future infected with unprecedented and unnecessary disease . . . . If we allow one segment of our society to suffer and perish from preventable disease, little stands in the way of collective doom. Ronald J. Glasser, MD
|In spite of the naturalistic fallacy, facts
are relevant to value decisions. Earlier we noted that
selection theory implies that the standard hierarchical
of the Bible regarding human dominion over all of Earth's
wrong.(22) We also noted a
practical reason for treating the rest of nature with
equals on this fragile planet. If we accept a common goal
survival and flourishing, if we care that our children
will be able to
have children, and their children to have children, and so
on, and if
natural selection theory is a reliable belief, then it
follows that sustainability and the care for and
diversity of the entire biosphere on Earth are good.
apparent short-term financial efficiency, if we
clone all our
domestic animals and
them in such appalling conditions that massive use of
required, we will endanger our
future. If we allow for
racism and ethnic cleansing, we will endanger our
weakening the diversity that will be necessary for the
human race to
ward off the inevitable viral mutations that will take
place in the
message is clear:
diversity and sustainability are good; environmental
uniformity very bad.(24)
Still the emotional response beckons: 100 billion to 400 hundred billion stars per galaxy, perhaps as many as 150 billion galaxies, hundreds of millions of chances at life on Earth and 99% extinct. Out of this relentless shuffling, there is now at least one creature capable of loving and thinking. On Earth the universe seems to have been in the business of experimenting with different forms of awareness and interfacing with the environment. Love and emotion are associated with bigger brains and greater awareness. Is this a unique situation? In this immensity of space and time are we the only creatures that have evolved to ponder such questions?
term race is
one of the most abused words in the English vocabulary
Every (human) population today consists of a multitude
genotypes. A pure
population or race, in
which all members are genetically alike, is
and Peter A. Rosenbaum, Understanding Evolution
Keep looking. The world holds more miracles--big, small, new, and old--than we can imagine. Lawrence Barns, fossil hunter, paleontologist
|There is no consensus yet whether, given
right conditions, the formation of DNA out of the right
is inevitable or a rare occurrence. Some scientists
believe that the
probability of forming such a complex molecule is so low
that it could
not have happened on Earth first. The possible chemical
occurring within an entire galaxy are needed. Others
believe that given
the chemical conditions that existed on Earth billions of
the formation of a self-replicating molecule is almost
There is agreement, however, that the basic chemical
for DNA formation existed not only on Earth approximately
years ago, but are common throughout the universe. Thus,
probability of life evolving in protected parts of each
galaxy may be
high. The universe could be teaming with life and
different forms of
awareness. Or, we could be totally alone. We will address
further in Chapter 9.
If the Darwinian view is true, however, the message is clear that there will be no human beings anywhere else. The likelihood of exactly the same sequence of events that produced mammals and human beings on Earth ever being repeated is infinitesimally small. On Earth there are countless events that could have occurred and we would not be here to contemplate these questions. Approximately 60 million years ago the evolutionary spread of the mammals became possible with the extinction of the dinosaurs. The evidence is now substantial, including the location of a 125-mile-diameter crater in Chicxulub, Mexico, that a large comet hit the Earth at that time. This impact produced a destructive force equivalent to numerous nuclear explosions, 5 billion times greater than the two atomic bombs used in World War II. Tons of dust and debris were thrown into the atmosphere, thus causing a drastic change in the climate. The dinosaurs, the dominant creatures on Earth for over 100 million years, could not adapt. If this comet had missed the Earth, the development of the mammals would likely have remained restricted to small, lowly, nighttime, ratlike creatures. There would be no monkeys, apes, and human beings.(25)
|The fact that the number of contingent factors necessary for human beings to evolve are too numerous to be repeated, and that highly successful creatures can vanish in a geological instant, are sobering, humbling thoughts. Why there is something rather than nothing, and why we are here is not as important as the fact that we appear to be a fortuitous part of this universe. We are here now, a complex creature with a complex evolutionary past. A "hopeful monster," a mixed bag of evolutionary survival strategies, capable of both great compassion and great destruction.|
| | |
1. St Augustine, Confessions. (Click Back to return to text.)
2. A species is defined in terms of what is called "reproductive isolation," meaning similar organisms that are capable of interbreeding and producing fertile offspring. In other words, a species is a group of organisms that are all part of the same "reproductive community."
3. David Attenborough, Life on Earth: A Natural History (Boston: Little, Brown, 1979), p. 15.
4. Gerald Feinberg and Robert Shapiro, Life Beyond Earth: The Intelligent Earthling's Guide to Life in the Universe (New York: William Morrow, 1980), p. 102.
5. David Attenborough, Life on Earth: A Natural History, (Boston: Little, Brown, 1979), p. 87.
6. This is perhaps unfair to the saber-toothed tiger. The saber-toothed tiger is often thought of as a brief freak experiment of nature. Actually it survived as a species for hundreds of thousands of years.
7. W. Martin, "Waiting for the End," The Atlantic, 249, June 1982, pp. 31-37.
8. Albert Einstein, Cosmic Religion (New York: Covici-Friede, 1931), p. 51.
9. Albert Einstein, Out of My Later Years (New York: Philosophical Library, 1950), p. 9.
10. Darwin, as was customary for his time, also gave some credence to use and disuse as a cause of variation. However, Darwin emphasized that use and disuse must be "largely combined with" or "overmatched by" natural selection. See page 177 of the 6th edition of On the Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life (London: John Murry, 1900).
11. Pope John Paul II, "Truth Cannot Contradict Truth," a lecture to the Pontifical Academy of Sciences, October 22, 1996.
12. During the early 1980's A.R. Thatcher, Britain's registrar general of population estimated that nearly 60 billion humans died between 40,000 B.C., the time of modern Homo sapiens, and A.D. 1980, nine times the present population.
13. As discussed in Chapter 1, it is also quite common today for astrophysicists to discuss and take quite seriously the possibility that our current universe is only a tiny bubble in an infinite sea of other universes.
14. It is also worth noting that a few weeks later, TV cameras captured another soccer phenomenon. This time, however, millions of viewers were shocked to witness a senseless riot where many people were killed.
15. Some species of alligator and frog take care of their young to some extent, and at least some dinosaurs are now believed to have practiced some child care. Recent fossil evidence has focused on the nesting behavior of Maiasaura, which means "good mother lizard."
16. Mammals first evolved some 200 million years ago, but they remained primarily small nocturnal creatures hiding from the dominant dinosaurs. As the dinosaurs disappeared 60 million years ago, mammals began to proliferate. Birds evolved from dinosaurs, and they, of course, also take care of their young.
17. Much overlooked by popular understanding of Darwin's famous work, On the Origin of Species by Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life, 6th ed. (London: John Murry, 1900), is his statement (p. 78), "I use the term (struggle for existence) in a large and metaphorical sense including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny."
18. See A Triune Concept of the Brain and Behavior, by Paul D. MacLean and Kral Adalbert Vojtech (Toronto: University of Toronto Press, 1973), and "The Triune Brain Evolving," American Journal of Physical Anthropology, 52, no. 2 (1980), p. 251; "Evolutionary Psychiatry and the Triune Brain," Psychological Medicine 15 (1985), pp. 219-221; "Brain Evolution: The Origin of Social and Cognitive Behavior," Journal of Children in Contemporary Society 16 (1983), pp. 9-21; "Brain Roots of the Will-to-Power," Zygon: Journal of Religion and Science 18 (1983), pp. 359-374; "Family Feeling in the Triune Brain," Psychology Today 15, no. 2 (1981): 100; The Triune Brain in Evolution: Role in Paleocerebral Functions (Kluwer Academic Publishers, 1990).
19. See Richard D. Alexander, The Biology of Moral Systems (New York: Aldine De Gruyter, 1987); Jared Diamond, The Third Chimpanzee: The Evolution and Future of the Human Race (New York: HarperCollins Publishers, 1992), and Robert Wright, The Moral Animal: The New Science of Evolutionary Psychology (New York: Pantheon Books, 1994).
20. We speak of the "possibility" and "potentiality" of other-directed values having a biological foundation. This foundation is an "open program" only; the actualization depends upon culture.
21. For instance, some creationists will point to the Cambrian explosion as evidence that life started on Earth all at once. But the empirical evidence is overwhelming that the Cambrian explosion started over 600 million years ago and extended for over 100 million years. Some also have claimed that the account of Noah's Ark and the flood in Genesis can account for the entire fossil record. This ignores the massive amount of empirical evidence for the reliability of dating techniques used by geologists and paleontologists.
22. The statement in the Bible regarding human dominion could mean that humans have a greater stewardship responsibility to care for the health of our planet than animals. Such an interpretation would be consistent with the message of natural selection theory.
23. Some people are naturally resistant to the AIDS virus. During the initial stages of the AIDS epidemic some fundamentalist Christians were unconcerned, seeing this as simply God's punishment of the homosexual life style. Because of their significant political influence, proactive government policies to combat the spread of AIDS were slow in developing. I repeat: beliefs matter, ignoring natural selection theory is like ignoring gravity.
24. This way around the naturalistic fallacy is called Instrumental Naturalism. It argues that a bridge can be made between facts and values via the clarification of goals. Right actions are seen as simply practical actions that serve as a means of achieving our goals given the facts of nature.
25. So in a very profound sense this comet
made us what we are today. According to the astronomer Neil de
Tyson, "We cannot simultaneously be happy that we live on a
happy that our planet is chemically rich, and happy that
don't rule the earth, yet resent the risk of a planet-wide
catastrophe." "Coming Attractions," Natural History,
Sept. 1997, p. 82.
Life on Earth: A Natural History, 1st American ed, by David Attenborough (Boston: Little, Brown, 1979).
A persuasive portrayal of the story of evolution and its infinite diversity, using pictures and discussion of living species of animals and plants resembling the extinct species that gave rise to the present life on Earth.
Extinction, by Steven M. Stanley (Scientific American Books: W.H. Freeman, 1987).
With drawings and photographs, Stanley takes the reader on a guided tour of the geological and biological history of the Earth. An excellent overview is given of the paleontological and geological evidence for mass extinctions.
The Flamingo's Smile: Reflections in Natural History, by Stephen Jay Gould (New York: Norton, 1985).
Perhaps Gould's best book. Like his previous books, Ever Since Darwin and The Panda's Thumb, Gould explores the fascinating quirkiness and messiness of evolution and the implications for meaning in life. Interpretations of Darwinism, the politics of science, mind in the Universe, and the issue of extraterrestrial life are covered.
Wonderful Life: The Burgess Shale and the Nature of History, Stephen Jay Gould (New York: Norton & Company, 1989)
Probably Gould’s most controversial book, because not only do many evolution theorists disagree with Gould’s “modifications” of Darwin, but even some of the paleontologists Gould praises in this book disagree with some of his interpretations of the Burgess fossils. However, no one can deny that Gould always makes a persuasive case. The cardinal theme (radical historical contingency) for much of Gould’s work is writ large in this book. Like the classic Jimmie Stewart movie It’s a Wonderful Life, one cannot replay the tape of life and get the same results. Just one contingent difference – no George Bailey – and apparent insignificance is magnified into a whole different history. Similarly says Gould,“Wind back the tape of life to the early days of the Burgess Shale; let it play again from an identical starting point, and the chance becomes vanishingly small that anything like human intelligence would grace the replay.”
Biophilia, by Edward Osborne Wilson (Cambridge, Mass.: Harvard University Press, 1984).
Unlike Wilson's Sociobiology and On Human Nature, two previous controversial books, Biophilia is a more personal and less technical presentation of the idea that the perplexities of human behavior can only be fully understood within the context of our biological history and its connection with the rest of the Earth's species. It is also a poetic and scientific appeal to see the rationality inherent in human concern for nonhuman species and their environments.
Evolution and Human Nature, by Richard Morris (New York, Seaview/Putman, 1983).
Although there have been many stimulating books that have attempted to relate the human condition to evolutionary biology and the modern study of ethology (Robert Ardrey's African Genesis, Konrad Lorenz's On Aggression, Desmond Morris's The Naked Ape, and Melvin Konner's The Tangled Wing, for example), this book is a good overview of the many issues and controversies. For a controversial introduction to the field of evolutionary psychology, see Robert Wright's The Moral Animal: The New Science of Evolutionary Psychology (New York: Pantheon Books, 1994).
The Blind Watchmaker, by Richard Dawkins (New York: W.W. Norton, 1986).
Abusing Science: the Case Against Creationism, by Philip Kitcher (Cambridge, Mass.: MIT Press, 1982).
Another antidote to the critics of
natural selection, focusing on Creationism, but at a deeper and
inclusive philosophical level. Kitcher, a professional philosopher
science, integrates the educational controversy between the
evolution and creationism in public schools with a philosophical
analysis of the nature of science. The book is also informative in
terms of the discussion of fossil details and evolutionary
and thought-provoking in defending the notion that modern
theory is not inconsistent with a sense of religion or morality,
evolution theory has "liberated us from misconceptions, and
aided us in our moral progress."
The Triumph of
Evolution and the Failure of Creationism, by
The Growth of Biological Thought: Diversity, Evolution, and Inheritance, by Ernst Mayr (Cambridge, Mass.: Belknap Press, 1982).
A must-read book by anyone interested
a complete academic understanding of the history and content of
evolution theory. Although over 800 pages, Mayr, formerly a
University professor and one of the major players of what is
"Neo-Darwinian synthesis," has written the definitive text on
evolutionary problems and their historical background.
What Evolution Is,
Ernst Mayr (
A large part of the
problem with the controversy over what to teach in public schools
that most people, including those highly educated, do not fully
understand what Darwin claimed and the modern evolutionary
extending Darwin’s work. A major
contributor to the modern evolutionary synthesis and acknowledged
his colleagues as the “world’s greatest living evolutionary
Mayr wrote this book in his late 90s as a primer on evolution for
general reader. When one finishes
this book, one will understand why Mayr says,
“It is now actually misleading to refer to evolution as a theory, considering the massive evidence that has been discovered over the last 140 years documenting its existence. Evolution is no longer a theory, it is simply a fact.”
The Origin of Species, By Means of Natural Selection or the Preservation of Favoured Races in the Struggle for Life, by Charles Darwin, 6th ed. (London: John Murray, 1900).
Although many evolution scholars
the "purity" of Darwin's first edition, this edition of the
source is recommended, because it contains additions and
resulting from Darwin's reflections on further evidence for
selection and criticism of his theory. For an introductory
of Darwin's writings, see The
Darwin, Robert Jastrow, general editor, with selections and
commentary by Kenneth Korey (Boston, Little, Brown and Company,
This book contains excerpts from Darwin's Autobiography, The
Voyage of the Beagle, Origin of Species, and The
Descent of Man.
It is important to note that Darwin
22 years accumulating evidence from the time he first conceived of
natural selection theory to the initial publication, and he
"rushed" this book into print in 1859 to be able to claim
priority. (Alfred Russel Wallace had arrived at the same
idea.) Plus Darwin considered this 500+ page book as only an
"abstract" of a planned much larger work!
Catholic, a professor of biology, and staunch defender of Darwin’s
theory of natural selection, this book is a must read for anyone
seriously interested in how one’s personal religious views need
in conflict with scientific truth. Miller
that not only are so-called scientific creationism and
intelligent design not scientific views and thus not worthy of
discussion in science classes, they are not needed by people of
faith. According to Miller, “To
people of faith, what
evolution says is that nature is complete. . . God fashioned a
world in which truly free, truly independent beings could evolve." He is also equally critical of those in
science or philosophy that believe that
Your Inner Fish: A Journey Into the 3.5-Billion History of the Human Body, by Neil Shubin (Vintage Books, 2009).
students are taught in human anatomy classes that the human body
be fully understood without understanding our body's
history. Shubin, a paleontologist and co-discoverer of
integrates fossil evidence and the new understanding of tool kit
to show the evolutionary biological history of the human body.
this book does not convince you of the reality of biological
on Earth, nothing will.
In page after page he shows how scientists are patiently
empirically the predictions of evolutionary theory. Important
demonstration that empirical science requires great patience.
describes the adventure of how it took his team six years to
Tiktaalik and then several more years in a lab to carefully
fossil bone from surrounding rock and analyze what they had
Ecological Developmental Biology: Integrating Epigenetics, Medicine, by Scott F. Gilbert and David Epel (Sinauer Associates, Inc., 2009).
a textbook that will probably be viewed as very technical from
point of view of a general reader, but a fascinating tour de
explanation and defense of the need for a Eco-Evo-Devo extension
natural selection theory. The
book not only covers many delightful examples from the natural
such as fish that change their sex and water fleas that grow
helmets when predators are detected in their environments, but
wades right into to foundational and philosophical issues in
evolutionary biology. Do developments in Eco-Evo-Devo warrant
revisiting of Lamarckian theory?