Considering the plethora of books about evolution out there, is it really necessary to publish yet another one? What can another book about evolution have to offer that previous books have not provided? This new book not only presents the latest information about evolution to come to light, but it also responds to the most recent attacks made upon this branch of scientific knowledge. The book, Why Evolution is True (NYC: Viking; 2009) by Jerry Coyne, is the most up-to-date and one of the most clearly written books about evolution that is currently available — and that’s saying a lot since most books about evolution are excellent.
This beautifully written and fascinating book delves into the answers to several questions; How has (and is) evolution tested scientifically? What predictions do scientists make based on the Theory of Evolution? Have these predictions been supported by the experimental evidence? This book is Coyne’s detailed presentation of the most impressive and modern discoveries of fossil, animal and plant data that have been published in a variety of scientific fields that impinge upon and contribute to The Theory of Evolution.
Take the field of biogeography, for example. Biogeographers have long known that there are two types of islands: oceanic islands, which arose from the seafloor and have never been connected to a large land mass and continental islands, which have become isolated from a large land mass sometime during their history due to rising sea levels or fracturing continental plates. Biogeographers have documented time and again that these two island types can be easily distinguished because all oceanic islands lack native mammals, amphibians and freshwater fish — animals that are present on continental islands. This is not due to any defects associated with continental life since humans have introduced continental species such as rats, goats, pigs and other domestic animals onto oceanic islands throughout history, demonstrating that continental species are quite adept at island life. Additionally, species found on oceanic islands are often very similar to each other — radiations from a few ancestral species — while those on continental islands are not.
“Why would a creator happen to leave amphibians, mammals, fish, and reptiles off oceanic islands, but not continental ones?” wonders Coyne. “Why did a creator produce radiations of similar species on oceanic islands, but not continental ones? And why were the species on oceanic islands created to resemble those from the nearest mainland?”
The fossil record is consistent with evolutionary biology, too. When paleontologists look for particular transitional forms, they are found in the fossil record precisely where they should occur if evolution occurred. For example, the earliest birds appear after dinosaurs but before modern birds, as we see illustrated on the front dust jacket cover of the book.
Primate fossils follow this same pattern. Coyne discusses a series of fossils that are intermediate between chimp and humans, where the older fossils are more ape-like while progressively younger fossils are those that possess more characters associated with humans. Creationists react to this by claiming that all of the great ape fossils are either humans or apes with no discernible intermediates, and that they are separated by “a large and unbridgeable gap.” But interestingly, when tested, creationists can’t agree among themselves as to exactly which fossils are “human” and which are “ape”. “Nothing shows the intermediacy of these fossils better than the inability of creationists to classify them consistently,” concludes Coyne.
Developmental biologists have identified atavisms that betray close evolutionary relationships, too. Atavisms are dormant ancestral features that are sporadically expressed during embryonic development and sometimes after birth, too. This is likely due to the activation of genes from an organism’s evolutionary ancestors that remain normally unexpressed. For example, humans possess the genes for making tails, but these genes are usually deactivated. But not always: page 63 has a photograph of a human infant with a 3-4 inch atavistic tail!
Speaking of genes, geneticists have also made some interesting discoveries, such as dead genes. Dead genes are those genes whose inactive sequences are found in the chromosomes of particular groups of organisms. “Virtually all species harbor dead genes,” Coyne notes, “many of them still active in its relatives.”
Dead genes are even found in the human genome. One example is the human inability to manufacture our own vitamin C — despite the fact that the necessary genes exist in our genome. A close look at the sequences reveals that just one gene has a mutation in it, and this is exactly the same mutation shared between all other primates, while guinea pigs, which also cannot make vitamin C, have a completely different mutation.
“Why would a creator put a pathway for making vitamin C in all these species, and then inactivate it?” Coyne asks. “Why would the same inactivating mutation be present in all primates, and a different one in guinea pigs?”
Even though Coyne’s initial motivation to write this book stemmed from his annoyance with those who claim that intelligent design is science, he doesn’t attack religion. Instead, as demonstrated in some of the passages I’ve quoted here, he does what scientists do best: he makes predictions. In this case, he makes predictions that naturally arise from evolutionary theory as well as from creationism and “intelligent design” and details how actual scientific data conflict with religious beliefs.
Coyne also includes an interesting section in the last chapter of the book where he explores the fear that evolution inspires in many religious people. He points out that religious opposition to evolution is not due to a lack of scientific evidence, for there is plenty of that, but it stems mainly from fears that the moral fabric of society will fall apart if people accept the fact that humans descended from ape-like ancestors. But that said, Coyne goes on to recognize that ethics are not the result of religious belief at all. Further, he is not deterred from using scientific findings to examine humans in the light of our evolutionary ancestry and postulating that this realization could mean a great deal for our future evolution.
Most of us do need meaning, purpose, and moral guidance in our lives. How do we find them if we accept that evolution is the real story of our origin? That question is outside of the domain of science. But evolution can sill shed some light on whether our morality is constrained by our genetics. If our bodies are the product of evolution, what about our behavior? Do we carry the psychological baggage of our millions of years on the African savanna? If so, how far can we overcome it? [p. 225]
I highly recommend this book to everyone who is seeking a clearly written and level-headed review of the most recent and relevant scientific findings and for how they support modern evolutionary theory.
Jerry Coyne earned his PhD in Biology at Harvard University under Richard Lewontin. Coyne is professor at the University of Chicago in the Department of Ecology and Evolution and currently teaches evolutionary biology, speciation, genetic analysis, social issues and scientific knowledge, and scientific speaking and writing. Previously, he has served as Vice President of the Society for the Study of Evolution, and as Associate Editor of Evolution and The American Naturalist. This is his second book: his first book, Speciation, was co-written with Allen Orr (Sinauer Associates, Inc.; 2004).