Michael Shermer, "The Fossil Fallacy" (2005)
ScientificAmerican.com; http://www.sciam.com/article.cfm?chanID=sa006&colID=13&articleID=0003EFE0-D68A-1212-8F3983414B7F0000
February 21, 2005
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The Fossil Fallacy
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Creationists' demand for fossils that represent "missing links" reveals
a deep misunderstanding of science
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Nineteenth-century English social scientist Herbert Spencer made this
prescient observation: "Those who cavalierly reject the Theory of
Evolution, as not adequately supported by facts, seem quite to forget
that their own theory is supported by no facts at all." Well over a
century later nothing has changed. When I debate creationists, they
present not one fact in favor of creation and instead demand "just one
transitional fossil" that proves evolution. When I do offer evidence
(for example, Ambulocetus natans, a transitional fossil between
ancient land mammals and modern whales), they respond that there are
now two gaps in the fossil record.
This is a clever debate retort, but it reveals a profound error that I call the Fossil Fallacy: the belief that a "single fossil"--one bit of data--constitutes proof of a multifarious process or historical sequence. In fact, proof is derived through a convergence of evidence from numerous lines of inquiry--multiple, independent inductions, all of which point to an unmistakable conclusion. We know evolution happened not because of transitional fossils such as A. natans but because of the convergence of evidence from such diverse fields as geology, paleontology, biogeography, comparative anatomy and physiology, molecular biology, genetics, and many more. No single discovery from any of these fields denotes proof of evolution, but together they reveal that life evolved in a certain sequence by a particular process. One of the finest compilations of evolutionary data and theory since Charles Darwin's On the Origin of Species is Richard Dawkins's magnum opus, The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution (Houghton Mifflin, 2004)--688 pages of convergent science recounted with literary elegance. Dawkins traces numerous transitional fossils (what he calls "concestors," the last common ancestor shared by a set of species) from Homo sapiens back four billion years to the origin of heredity and the emergence of evolution. No single concestor proves that evolution happened, but together they reveal a majestic story of process over time.
We know evolution happened because of a convergence of
evidence.
Consider the tale of the dog. With so many breeds of dogs popular for so many thousands of years, one would think there would be an abundance of transitional fossils providing paleontologists with copious data from which to reconstruct their evolutionary ancestry. In fact, according to Jennifer A. Leonard, an evolutionary biologist then at the Smithsonian Institution's National Museum of Natural History, "the fossil record from wolves to dogs is pretty sparse." Then how do we know whence dogs evolved? In the November 22, 2002, Science, Leonard and her colleagues report that mitochondrial DNA (mtDNA) data from early dog remains "strongly support the hypothesis that ancient American and Eurasian domestic dogs share a common origin from Old World gray wolves." In the same issue, molecular biologist Peter Savolainen of the Royal Institute of Technology in Stockholm and his colleagues note that even though the fossil record is problematic, their study of mtDNA sequence variation among 654 domestic dogs from around the world "points to an origin of the domestic dog in East Asia" about 15,000 years before the present from a single gene pool of wolves. Finally, anthropologist Brian Hare of Harvard
University and his colleagues describe in this same issue the results of
a study showing that domestic dogs are more skillful than wolves at
using human signals to indicate the location of hidden food. Yet "dogs
and wolves do not perform differently in a nonsocial memory task, ruling
out the possibility that dogs outperform wolves in all human-guided
tasks," they write. Therefore, "dogs' social-communicative skills with
humans were acquired during the process of domestication." |