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

We need another, wiser, and perhaps a more mystical concept of animals. For the animal shall not be measured by man....They are not underlings. They are other nations, caught with ourselves in the net of life and time, fellow prisoners of the splendor and travail of Earth.  Henry Beston

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

New knowledge leads us to recognize that the theory of evolution is more than a hypothesis.  Pope John Paul, Address to the Pontifical Academy of Sciences, October 1996

There is another form of temptation, even more fraught with danger. This is the disease of curiosity. . . .[emphasis added] It is this which drives us on to try to discover the secrets of nature, those secrets which are beyond our understanding, which can avail us nothing and which men should not wish to learn. . . . In this immense forest, full of pitfalls and perils, I have drawn myself back, and pulled myself away from these thorns. In the midst of all these things which float unceasingly around me in everyday life, I am never surprised at any of them, and never captivated by my genuine desire to study them. . . . I no longer dream of the stars.⁽¹⁾

By 2009, opinion polls revealed that over half of the people in the United States 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 years ago without evolution playing any role.  Although a substantial percentage (27%) apparently believed that God and evolution work together in some fashion, only 13% of the people in the United States believed that, once life begins, evolution is a process of 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 that "evolution is a fact, not a theory," and there is almost unanimous 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 not believing in or understanding this mechanism is as dangerous as not understanding gravity or the connection between lung cancer and cigarette smoking.

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 natural mechanism produced these changes over such a vast span of time. When the theory of evolution is 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 selection refer to it as "only a theory," implying that it is only a 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 politician Rick Perry, but one of the most confirmed and corroborated inductive generalizations of our time, a generalization that accounts for such an extensive amount of data that it serves as a guiding mental framework for research in many sciences, especially modern biomedical research.  As a highly corroborated and tested theory it is "more than a (mere) 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.

We are not here concerned with hopes and fears, only with the truth as far as our reason allows us to discover it. I have given the evidence to the best of my ability; and we must acknowledge ... that man with all his noble qualities, with sympathy which feels for the most debased, with benevolence which extends not only to other men but to the humblest living creature, with his godlike intellect which has penetrated into the movements and constitution of the solar system ... Man still bears in his bodily frame the indelible stamp of his lowly origin.  Charles Darwin, The Descent of Man

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.  Charles Darwin, On the Origin of Species

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. 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 is 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 of producing lots of the diversity needed for the changing selection pressures from the environment, because having the right characteristics at the right time is a matter of enormous contingency, eventually most creatures will not have the characteristics to adapt to the new environment.  Accordingly, it is very important to realize that Darwin's theory predicts that extinction will be a common feature of the natural world. In this sense the basketball and horse racing examples above are misleading. From a Darwinian perspective one 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 original species and the entire lineage comes to a complete dead end. That particular branch of the tree of life falls off and ceases to exist.  Remember this crucial point.  Darwin's remarkable theory predicts that the history of life on Earth will not only show fantastic success, but also inevitable eliminative failure.

We 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,

Since the discovery of radioactivity scientists have realized that rocks have a geological clock within them. Several chemical elements decay with age, producing radioactivity in the process. Potassium turns into argon, uranium into lead, rubidium into strontium. The rate at which this happens can be estimated. So if the proportion of the secondary element to the primary one in a rock is measured, the time at which the original mineral was formed can be calculated. Since there are several such pairs of elements decaying at different speeds, it is possible to make cross-checks...[Thus] anyone can date many rocks in a relative way by simple logic and by doing so put into order the major events of fossil history. If rocks lie in layers...then the lower layer must be older than the upper. So we can follow the history of life through the strata and trace the lineages of animals back to their beginnings by going deeper and deeper into the earth's crust.⁽³⁾

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 tests.  Consider some examples. Scientists recognized based on anatomy and morphology that camels living in Africa and llamas living in South America seem related.  But if evolution is true, why would they be so far apart?  There are no camels or llamas living in North America. The theory must predict that ancestors to camels and llamas existed in North America at one time.  This prediction has been confirmed with the discovery of 40 million year-old fossil examples of extinct camels in North America.

In 1859, 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 ancestors would someday be found in Africa. Today, after over a hundred years of searching paleontologists have found over a dozen extinct species.

In 2006, paleontologists announced the discovery of Tiktaalik, an extinct fish with key transitional features to land animals. 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 years fully extricating the fossil from surrounding rock. But it was no accident that they were looking where they were looking. Oil and gas exploration to feed an exploding global energy appetite, advanced imaging technology, and Internet data bases of geology all over the world 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 other fossil finds that the transition from water to land for fish-to-amphibian-like creatures would be about 360-400 million years ago.  Then with luck and formidable endurance a fossil of Tiktaalik was found.  The surrounding rocks were dated at 375 million years old. Almost daily we learn that time is on the side of Darwin as more and more predictions are confirmed with new fossil finds.

As we will see, of all the competing theories the Darwinian mechanism of natural selection alone predicts massive extinction. Because major variation within a species will occur independently of changes in the environment, an eventual mismatch between a species 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 its wonderful success, but the massive number of examples of failure as well.  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 fossil record -- 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 interpretation of the Noah's Ark story, see Mark Isaak's Problem with a Global Flood.

Up to a million species have been identified in the fossil record.  At least a billion and perhaps up to 50 billion species may have existed on Earth.  Judging from the fossil record 99.9% of all the species that have lived on Earth are now extinct. (About 1.8 million living species have been described and classified, with conservative estimates of 10 million living species on Earth at present.) To those trained in anatomy, geology and paleontology, there is impressive evidence of common ancestry, that each of the species at the tips of the evolutionary tree developed from earlier ones.  And again remember this crucial point.  For every branch that survives, innumerable side branches are seen, all living and prospering for a time, but leaving no higher branches.  To take but one example, the fossil evidence for the evolution of the modern horse (Equus) from a distant ancestor (Eohippus) is remarkably complete.  But this small part of the great evolutionary bush 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 family tree from the Florida Museum of Natural History.

If superior creatures from space ever visit Earth, the first question they will ask in order to assess the level of our civilization, is: "Have they discovered evolution yet?"  Richard Dawkins

(HIV is) nothing but a speeded up and microscopic case of what Darwin saw in the Galapagos – except that each human body is an island, and the newly evolved forms aren’t so charming as finches or mockingbirds.  David Quammen

Can we see evolution in action?  Can it be observed in the wild?  Can it be measured in the laboratory?  The answer is yes . . . With patience it can be seen, like the movement of a minute hand on a clock.  David Quammen

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 udders full of milk, seedless fruit, and the extinction of many species. The human species has sculpted nature in much the same way the natural environment has by accident. Furthermore, disease causing 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 resistant members 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 environment.

For the health and welfare of present and future generations, no aspect of science is more important than biomedical science.  And no aspect of biomedical science is more important than the study and control of microbial diseases.  Only from the perspective of natural selection can the dynamics of viruses and 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 United States alone are killed by new flu viruses that evolve each year.  In 1995, over 80,000 people in the United States died from drug resistant bacterial infections evolved, not in spite of, but because of the sterile conditions of some of our safest places – hospitals.  Since Penicillin became available in 1943, a deadly one step ahead battle has been fought against the deadly Staphylococcus bacteria, with medical science racing to keep up with the development of new antibiotics to counter the inevitable new evolutionary strains of this bacterium.  With the general public and political leaders not understanding the basics of natural selection, public health officials worry that it is just a matter of time when our overprescription by physicians of antibiotics and massive application of antibiotics in agribusiness – antibiotics that are flushed into streams, rivers, and oceans, fueling natural selection in microbial life throughout the world – will create pandemics far greater than HIV and previous world-wide flu epidemics that killed millions of people.  There is a very good reason that scientists go ballistic when school boards suggest that evolution should be taught as “only a theory.”  Not teaching it as a basic law of life is indeed as dangerous as ignoring gravity.  See Figure 3-3.

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 moth flourished in Great Britain. Its color made it almost invisible when it landed on a tree covered with grayish lichen, a type of fungus, making it difficult for birds, the moths' natural predator, to spot them. As the industrial revolution intensified, smoke and pollution killed the lichen and darkened the trees, thus making the moths easy targets for birds. A "black sheep" version of this moth had appeared earlier, but 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, the original peppered variety began to flourish again, and the darker variety was suppressed.

Can evolution be observed in the laboratory?  Fortunately or unfortunately, evolution is not only observed, new life forms are created now routinely by microbiologists by directly creating the variations (via DNA tinkering) that match or don't match particular environments.  Multiple generations of fruit flies have been observed and tinkered with and thousands of generations of Escherichia bacteria have been tracked.  All the experimental results match Darwinian predictions.  The DNA expression in embryos of chickens can be manipulated to produce chickens with teeth (the ancestors had 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.

Why should the embryos of birds and mammals develop gill slits, like fish embryos?  .... whatever aspect of biology is studied, it provides irrefutable evidence in support of evolution.  Earnst Mayr, What Evolution Is

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 evolved from a land ancestor with a dog-like or antelope-like body. See Figure 3-6.  The embryos of both whales and dolphins show evidence of this phylogeny in that they have four leglike buds, the two hindmost usually being reabsorbed before birth and the two front developing into flippers. The flippers have an internal bone structure similar to all land 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 before birth. Vestigial characteristics not only show nature's imperfection -- important for the raw material of evolution from a Darwinian point of view -- but also often show the remnants of an evolutionary 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.

Nothing in biology makes sense except in the light of evolution.  Theodosius Dobzhansky

What is gratifying is the fact  that when a phylogeny based on morphological or behavioral characteristics is established, it is usually found to be essentially the same as a phylogeny based on exclusively on molecular characteristics.  Ernst Mayr, What Evolution Is

We will need to know what is true to decide what is right.

Imagine a house coming together spontaneously from all the information contained in the bricks: that is how animal bodies are made.  Neil Shubin, Your  Inner Fish

. . . in addition to helping decide the survival of the fittest, the environment is also important in formulating the arrival of the fittest. Scott Gilbert and David Epel, Ecological Developmental Biology

Nature interests me because it's beautiful, complex, and robust. Evolution theory interests me because it explains why nature is beautiful, complex, and robust. David Quammen

. . . 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 intellectual patrimony of humankind.  Even plasticity is a selectable trait.  Scott Gilbert and David Epel, Ecological Developmental Biology

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, and those involved in biomedical research now have tools that can rapidly read DNA sequences not only of humans but many other creatures from microbes to apes. Every creature alive today has DNA full of fossil genes.  Chickens have genes for teeth that are no longer expressed.  Blind 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 normal vertebrate blood and the gradual genetic changes that have occurred over millions of years from their red blooded ancestors can be mapped in remarkable correspondence with the independent geological knowledge 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 relatives -- orangutans, gorillas, and chimps. Somewhere in our primate lineage a common ancestor to humans and apes lost the ability to synthesize its own Vitamin C in its liver.

Linking animal morphological and behavioral characteristics in evolutionary relationships can now be corroborated by comparing their genes.  Anatomical, behavioral, and fossil evidence links 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 humans and 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.

Imagine a process in which you select a place in the text of Hamlet at random. You then decide arbitrarily whether one or more words are to be removed, added, or exchanged for new ones. If new words are to be added or used to replace existing ones, you select them, again at random from a dictionary. Usually this process will not increase the literary value of the play . . . . In very unlucky cases, the meaning of an entire section may be damaged. In rare instances, however, the text will be improved. The play may have been optimal for its original audience, and at that time any changes made by the random process would have been for the worse. But changes in society and language since the play was written have made Hamlet increasingly less understandable to modern audiences. (This is analogous to a need for adaptation of an organism due to changes in its environment.) It is a tribute to the genius of its creator that Hamlet has retained so much meaning after the passage of centuries. One can see, however, that if the random replacement process were carried out a great many times and if the errors were discarded and improvements preserved, an updated Hamlet would eventually be produced.⁽⁴⁾

At the present time, biology has more to do with the problems we face, and our future as a species, than does any other science.  Ernst Mayr
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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,

Insects swarm in deserts as well as forests; they swim below water and crawl in deep caves in perpetual darkness. They fly over the high peaks of the Himalayas and exist in surprising numbers on permanent ice caps of the Poles. One fly makes its home in pools of crude oil welling up from the ground; another lives in steaming hot volcanic springs. Some deliberately seek high concentrations of brine and others regularly withstand being frozen solid. They excavate homes for themselves in the skins of animals and burrow long winding tunnels within the thickness of a leaf.⁽⁵⁾

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.

There is an important message in this view of life. Because its attitudinal focus is humility, natural selection as a law of nature is not necessarily inconsistent with a belief in a supreme being, anymore than believing in the law of gravity is inconsistent with being a Christian, a Jew, or a Muslim. However, our consistent philosophical bias of our "specialness," which permeates most of our religions, philosophies, and politics -- this bias that somehow we are guaranteed a necessary survival and justice -- has led us repeatedly to indulge in frivolous destructive behavior. Throughout human history the greatest 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 Soviet Union. 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⁾ Today, some radical Islamists believe they will be assured of a special place in heaven by killing people they disagree with religiously and economically.

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.

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 tend to predominate in a much more directed way than in the Darwinian scenario. The elevating of the food source of the pre-Okapi would cause a stretching of the muscles of the legs and neck, eventually resulting in offspring with longer legs and necks. Somehow the new behavior would cause a change in the animal's genes. 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. Or, the creature is not able to mate. 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. Hence, even granting the possibility of epigenetic and flexible changes in form due to environmental influences, the Darwinian scenario predicts a much messier long term outcome.  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 ancestors and close relatives are extinct, most dying because they did not have the right blood at the right time to withstand severe cold. The fortuitous gradual changes that allowed another ancestor to slip through an environmental window of gradual cooling of its environment is not likely to be repeated backwards if global warming radically changes 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 temporary.

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 rest of the world that accepting natural selection theory is not 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 of gravity. Recognizing that death makes way for new life seems no different than acknowledging the fact that we all die to make way for new generations.  If God exists, why would He not be a Darwinian?

What is intriguing about Lamarckism, and undoubtedly one of the reasons for its staying power, is that it incorporates in scientific form, or at least attempts to, the major philosophical objection mentioned earlier. Life appears to be too intricately adapted to every environmental niche to be an accident. Human beings appear superior to other creatures, we have conscious minds that many have a hard time believing can be reduced to mere physics and chemistry, and Lamarckism implies that humankind is a superior end product of evolution. When Darwin first proposed the theory of natural selection, 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 a bungler. Today new approaches have emerged that also reject the orthodox Darwinian position and claim not only to be more consistent with the Bible but also to be better scientific theories.

These views have come to be known as scientific creationism and intelligent design. Proponents of scientific creationism argue that no evolution has taken place on Earth and all life was created during the same time frame about 10,000 years ago, a time frame incredibly shorter than that portrayed in standard geology textbooks (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, physics, and 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 "microevolution" within 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 basketball culture would be an example of macroevolution.) They argue, however, 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 an undirected and unplanned process. Essentially those who support scientific creationism are young-Earth creationists and those who support intelligent design are old-Earth creationists. Both groups have lobbied throughout the United States for equal treatment in science textbooks 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. Even 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 microorganisms, about 4 billion years ago, to the Cambrian explosion, about 580 million years ago and the beginning of 99 percent of the evolutionary development on Earth. It is imagination that fills in these gaps, not evidence, so the creationists maintain. If the dates are wrong, the 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.

The truth may not be helpful, but the concealment of it cannot be.  Melvin Konner

Inductive evidence is always incomplete; the conclusions always go beyond the evidence. The constant challenge is to be able to separate the most reasonable view from all the conceivable ones.

The tale of (hominid skulls) is creationism’s worst nightmare …. the fossil record of human evolution is one of the very best, most complete, and ironclad documented examples of evolutionary history that we have assembled in … paleontological research.  Niles Eldredge, The Triumph of Evolution and the Failure of Creationism

. . . the little tooth  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

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 interpretation of fossils, scientists debate, critique, and discuss each others' 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 fossilized reptiles. Mammalian teeth are diverse, functional for a diverse diet. Sharp teeth in front for cutting, canine teeth in the middle for puncturing, and flatter teeth in the back of the mouth for grinding. Fossils have been found around the world of a small rodent-like creature that lived 150 million years ago. From its teeth alone (diverse with frontal incisors, middle canines, and back molars) we can intelligently infer that it was one of the first mammals.

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.

The celestial 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
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Given so 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?

This world is only the first rude essay of some infant deity, who afterwards abandoned it, ashamed of his lame performance. David Hume
 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
If there is anything divine in man, it is that his front paws were liberated at some remote time to the freedom which lets them clutch, carry, feel, measure, compare!  Homer Smith

How 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

In a science class one is professionally and ethically obligated to teach the best theories and our most reliable knowledge.

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.

Modern supporters of intelligent design theory will argue that fossil record is actually inconsistent with Darwin’s theory because there are too many instances of complexity showing up “too soon” in the fossil record.  For instance, recall the trilobite eye mentioned in Chapter 1.  How could such a sophisticated design for eyesight have evolved so early, 400 million years ago, right after the Cambrian explosion?  A similar design was not discovered for telescopes by intelligent human beings until the 17^th century.

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?

Failure of 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.

It is possible 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.
 

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 because of the notion of purpose. An old and vast universe that is Darwinian does not seem to fit the story that the universe was planned just for us. Humans appear to be an accident and an afterthought of billions of years of contingency. That the universe existed for billions of years before we could presumably take center stage seems to be inconsistent with the story that we are important and the main focus of attention. However, supporters of natural selection theory and a belief in God respond that we should not be too quick to judge God's intentions. 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. Furthermore, 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 question whether evolution might also be part of God's plan when we discover that 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 underscores the importance of the same contingency that plays such a major role in natural selection theory.

I 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 all.  Ecclesiastes 

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.

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.

What options are left in the  face of geology's most frightening fact? Only two, really.  We may ... accept the implications and learn to seek the meaning of life, including the source of morality in ... appropriate domains -- either stoically with a sense of lose, or with joy in the challenge if our temperament be optimistic.  Or, we may continue to seek cosmic comfort in nature by reading life's history in distorted light .... May our poor and improbable species find joy in its new-found fragility and good fortune.  Stephen Jay Gould, Wonderful Life

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 note, even the great British naturalist, Alfred Russell Wallace, the co-originator with Darwin of the theory of natural selection, declined to apply this theory completely to the evolution of the human species. There is, thought Wallace, such an obvious moral distinction between the valueless world implied by natural selection and the potential 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 noble values.

It 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

It is 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, Understanding Evolution

Suppose love is an accident, a result of a fortuitous change in reproductive strategy? Should it be valued any less?

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

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.

Some men 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⁾

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.

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.

No body of beliefs that has its origin in doctrinal material rather than scientific observation, interpretation, and experimentation should be admissible as science in any science course.  Incorporating the teaching of such doctrines into a science curriculum compromises the objectives of public education.  National Academy of Sciences, Science and Creationism

Why would an intelligent serial creator produce a newly designed watch by leaving all the broken pieces of previous designs inside?

There is no comparison between the successful predictions of evolution theory fulfilled almost daily and predictions from the Creationists, such as the dinosaurs still alive and hiding somewhere in Africa. What is 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 astronomy, biology (biogeography, embryology, morphology, genomics and population genetics, biochemistry, molecular biology, and paleontology), 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 theory, no view is remotely close to matching the empirical evidence.

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 selection theory in the science classes of public schools. Such opposition is often portrayed as dogmatic by supporters of creationism and intelligent design. In a democracy should we not introduce children to both views? Of course, scientists will respond, perhaps in religion and philosophy classes, but in a science class one is professionally and ethically obligated to teach the best theories and our most reliable knowledge. 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 tall buildings. Similarly, it would be morally and professionally irresponsible for a biologist to teach children that creationism is equal in evidence to natural selection. The consequences are enormous. A society that ignores a law of nature such as gravity will make disastrous decisions. A society that ignores the message of natural selection is not likely to survive.

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?

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⁾