A colleague suggested I post in several installments my past response to critics of Icons of Evolution. The series begins here, which includes the full reviewer citations.
Part 6: Human evolution
The evidence for human evolution will always be meager in comparison with evidence drawn from other species. Experiments involving mutation and selection that can be performed with bacteria, animals and plants cannot be done with humans, because they would be both impractical and unethical. So evidence for the processes of evolution necessarily comes from organisms other than human beings.
As for patterns in the history of life: The vast majority of animal fossils are marine invertebrates. Fossils of land vertebrates are comparatively few and far between, and fossils of the ape-like creatures that supposedly evolved into humans are so exceedingly rare that their discovery is usually announced on the front pages of newspapers.
According to Scott, I exaggerate the scarcity of fossil relating to human origins. She complains that I ignore “the many significant discoveries of the past two decades,” giving readers the incorrect impression that “the human fossil record is unusually weak.” (Scott, p. 2258) Yet Martin writes: “Wells seems to accept the fossil evidence at face value,” so that the story of human evolution “remains intact using evidence that he allows.” (Martin, pp. 244-245) Coyne’s only objection is that I can “only mumble” when “faced with a series of hominid fossils showing transitions from ape-like to modern human traits over 4 million years.” (Coyne, p. 745) And Pigliucci writes: “Wells, as much as he desperately tries to debunk” the ape-to-human icon, “is backed against the wall by his own knowledge” of the fossil record. (Pigliucci, p. 413)
So reviewers Martin, Coyne and Pigliucci don’t think that I’m ignorant of the fossil evidence for human origins; they complain that I’m unwilling to grant that it demonstrates Darwinian evolution. And they’re right: Although a series of fossils may be consistent with Darwin’s theory of descent with modification, I do not think it is sufficient evidence for that theory. And I’m not the only biologist who thinks this.
Henry Gee, chief science writer for Nature, wrote in 1999: “The intervals of time that separate fossils are so huge that we cannot say anything definite about their possible connection through ancestry and descent.” Although Gee is a believer in Darwin’s theory, he acknowledged that one must assume the truth of the theory when studying human origins, because by its very nature the fossil record cannot corroborate it. Gee concluded: “To take a line of fossils and claim that they represent a lineage is not a scientific hypothesis that can be tested, but an assertion that carries the same validity as a bedtime story--amusing, perhaps even instructive, but not scientific.” [18]
I would go further than Gee, and point out that a series of fossils is just as consistent with intelligent design as it is with Darwinian evolution. Even if we had a complete fossil record of all animals that lived before the advent of human beings, it would not establish that the latter evolved from the former through descent with modification. This point was unwittingly illustrated by Ohio State University biologist Tim Berra in his 1990 book, Evolution and the Myth of Creationism. Berra compared the fossil record to a series of automobile models: “If you compare a 1953 and a 1954 Corvette, side by side, then a 1954 and a 1955 model, and so on, the descent with modification is overwhelmingly obvious. This is what paleoanthropologists [people who study human origins] do with fossils.” (Emphasis in the original) [19]
But we all know that automobiles are designed, so Berra’s analogy makes it clear that a sequence of fossil forms can be explained just as well by design as by Darwinian evolution. This is why one must first assume Darwin’s theory in order to get an evolutionary story out of the fossil evidence. [20] As Gee acknowledged, however, such a story is untestable, and thus has no more scientific validity than a bedtime story.
NOTES:
[18] Henry Gee, In Search of Deep Time: Beyond the Fossil Record to a New History of Life (New York: The Free Press, 1999), pp. 23, 116-117.
[19] Tim M. Berra, Evolution and the Myth of Creationism (Stanford: Stanford University Press, 1990), p. 117.
[20] This problem has long been familiar to paleontologists concerned with the relationship between theory and evidence. In 1974, for instance, David Kitts observed that “the claim is made that paleontology provides a direct way to get at the major events of organic history and that, furthermore, it provides a means of testing evolutionary theories. This claim raises the critical question of how close we can get to evolution without presupposing some causal theory of descent. ... [T]he paleontologist can provide knowledge that cannot be provided by biological principles alone. But he cannot provide us with evolution.” (D.B. Kitts, “Paleontology and Evolutionary Theory,” Evolution 28 [1974]: 458-472, p. 466) In 1982, Keith Thomson noted: “Although ‘finding ancestors’ is the traditional paleontologists’ ‘proof ,’ such ‘historical events’ cannot be tested by assembling nice series of fossils without discontinuities, because the evolutionary hypothesis is superficially so powerful that any reasonably graded series of forms can be thought to have legitimacy. In fact, there is circularity in the approach that first assumes some sort of evolutionary relatedness and then assembles a pattern of relations from which to argue that relatedness must be true.” (K. S. Thomson, “The meanings of evolution,” American Scientist 70 [1982]: 529-531, pp. 529-530) [I am indebted to Paul Nelson for providing these references.--JW]
