by Kenneth W. Krause.
Kenneth W. Krause is a contributing editor and “Science Watch” columnist for the Skeptical Inquirer. Formerly a contributing editor and books columnist for the Humanist, Kenneth contributes regularly to Skeptic as well. He may be contacted at firstname.lastname@example.org.
True, nearly 150 years following Darwin’s initial publication of On the Origin of Species, about half of Americans still believe that humans and dinosaurs coexisted at some point in natural history. About half deny that people evolved from earlier species. And, true, if one mentions the evolution of species outside of a laboratory or classroom, then one should also expect an unfortunate response something along the line of, “I don’t believe it! After all, I’ve never seen half a cat!”
So why should we care? Why not let people believe what they will? Because it’s simply too late for that, answer educators Cameron Smith and Charles Sullivan. Socially, intellectually, scientifically, and technologically, we’ve come entirely too far to reverse course. Evolution is as critical to biology as electricity is to a pop-up toaster, and every citizen’s basic comprehension of biology is prerequisite to her ability to effectively confront crucial and now unavoidable issues like disease prevention, environmental protection, the safety of endangered species, stem cell research, genetic engineering, etc., ad infinitum.
So how to begin? Perhaps with The Top Ten Myths About Evolution, suggest Smith and Sullivan, whose new text certainly looks and, upon first glance, feels like yet another in a recently long line of politically motivated and simplistic overviews of evolutionary history and science. Then again, Top Ten Myths has been impressively researched, thoughtfully documented, and generally well written. Although each chapter has at least something important to say, or to repeat, as the case may be, more informed readers might find the observations and insights tucked away in the generous endnotes more stimulating. On the whole, then, Smith and Sullivan have managed to tender something challenging for some and valuable for all.
For instance, following a critique of the “myth” that evolution is “just a theory,” the authors relate not only the bare distinction between Darwin’s original theory and neo-Darwinism (or the modern synthesis), but also the somewhat more obscure facts surrounding Darwin’s pangenesis hypothesis. Oblivious to the genetic basis of natural selection, Darwin seriously considered the possibility that traits acquired during an organism’s lifetime could be passed along to its offspring. Tiny particles called gemmules, he speculated, would penetrate an organism’s sex organs, adding to its cache of reproductive information. If nothing else, this brief discussion highlights the provisional nature and thus unparalleled dynamism of all science.
More predictably, Top Ten Myths delivers a polemic that, although factually appropriate, often borders on the needlessly apologetic and, in the end, the intellectually disingenuous. Throughout the text, the authors defend evolution by one means or another against the teleological “Great Chain of Being,” the Scala Natura, or its persistent remains, apparently presuming a religious but theologically manipulable audience.
The medieval Great Chain classified all things hierarchically, from the strictly material (rocks, for example) to the purely spiritual (angels, archangels, and, of course, God). All living things were fixed according to the seamless plan of a perfect creator. The scheme infested more than religion, however, influencing Lamarck’s conclusion as well that species eventually progressed up the Chain as a result of each member’s lifetime achievement. Smith and Sullivan effectively rebut the mistake of progress by noting that bacteria, rats, and cockroaches are, and will likely always be, among the most successful species on earth, and by reminding us that some organisms, internal parasites and cave-dwelling fish included, have actually grown less complex over time. Similarly, the authors call attention to the metaphysical inconsistency of inferring an evolutionary purpose from a planet that has experienced at least five mass extinctions in the last 440 million years.
Because the Chain implied permanently distinct and easily identifiable species, its legacy frequently seduces modern religionists into an exaggeration of the fossil record’s “missing links,” or alleged want of transitional forms. Such gaps, of course, can be explained in a number of ways. No doubt every naturally abrasive force from tectonic shift and volcanism to simple erosion can be blamed to some extent. But not every organism can fossilize, especially those with soft bodies. And those that can fossilize must surrender themselves at the right time under opportune circumstances in order to do so. Bones, teeth, and shells will suffice, assuming a sedimentary environment, but even they will most often fragment, crumble, and deteriorate long before they can fossilize.
As for the “half a cat” quandary, species classification is not, and perhaps will never be, a visually or conceptually satisfying, less said an exact, science. Although speciation is considered a function of reproductive isolation, as the authors point out, lions and tigers, for example, can mate and, at least in captivity, produce baby “ligers” or “tigons,” whichever you prefer. Genetically, they are considered one species but, behaviorally, lions and tigers are diverse enough to merit separate classification. Regardless, kitties become kitties very slowly, over greater spans of time than human brains have evolved to contemplate, much less comprehend in any meaningful way. And although cats are always changing, their genes forever drifting and adapting, it is certainly true that one will never witness a creature that is half cat and half something else. So be it.
But so-called “missing links” have been found, between fish and amphibians, amphibians and reptiles, and reptiles and mammals. The remains of archaeopteryx, for example, revealed a crow-sized creature sporting both bird and lizard-like features. We have located as well the fossils of warm-blooded reptiles called therapsids, and of many transitional species leading from Eohippus to the modern horse. And time and again we have unearthed the fossils of our own ancestors which are neither Homo (of the human genus) nor Pan (of the chimpanzee genus), but rather Australopithecus (meaning southern ape): large, bipedal African hominids with relatively small brains, the earliest members of which lived four to six million years ago, when they diverged from forest-dwelling chimp and gorilla-like primates. These creatures separated into two groups: the robusts, which died out about one million years ago, and the graciles, which might have been our ancestors. Lucy, in fact, was a 3.2 million year old australopithecine discovered in Ethiopia in 1974.
The Great Chain, of course, has most recently culminated in the unfortunate doctrines of creationism and its thinly veiled cousin, Intelligent Design. Smith and Sullivan devote a chapter to each, adequately exposing them for what they really are—blunt but effective tools of religious desperation. In the process, however, the authors draw an unhelpful distinction between philosophical and methodological naturalism, the former rejecting anything that purportedly cannot be explained by natural laws and the latter withholding all possible judgment in that regard. In the end, they observe, science has nothing to say about gods and souls so long as we assume such things are not part of the physical world. And belief in God (yes, “God” with a capital, monotheistic, Abrahamic “G”), the authors vie, “is not incompatible with evolution or science in general.”
Belief without evidence—in fact, belief impervious to all evidence—is not incompatible with science? Such is either the mother of all politically convenient cop-outs or unmistakable confirmation that the Great Chain’s influence persists, at least with respect to its preposterously naive segregation of humanity and its God. Moreover, we simply cannot assume, as much as we might like to, that God and his alleged carryings-on are not part of the physical world. To the contrary, the Abrahamic texts make it painfully, brutally, agonizingly clear that God has supposedly had a great deal to do with us and our planet. As Smith and Sullivan had at least begun to say, we simply can’t afford to continue to offer these kinds of compromises.