Paleontology and Evolution

Review of Evolution: What the Fossils Say and Why It Matters, by Donald R. Prothero. 2007. Columbia University Press, New York. 408 pp. Cloth, $29.50. ISBN 978-0-231-13962-5. Paleontology has long occupied a somewhat marginal place in the evolutionary biological sciences?a situation (almost nobody will dispute) arising from its treatment in our Founding Document: Darwin's (1859) On the Origin of Species by Means of Natural Selection. Darwin essentially invented taphonomy (the study of all the things that can prevent a once-living organism from ending up on a paleontologist's laboratory table) to explain why the fossil record supported his theory only in the broadest terms. Yet, ironically, what is often overlooked is that Darwin got his first taste of what was soon to become his theory when the Bea gle stopped at St. Jago in the Cape Verde Islands in mid-January 1832, only 2-1/2 weeks after leaving England. There he collected the shells of marine invertebrates along the strand, with a nearby limestone outcrop providing fossils of some of the very same species. The fossil specimens and their modern equivalents ap peared to him to be identical. And after an interlude of captivation by the Brazilian Atlantic rainforest (arguably the birth of "biodi versity") Darwin was truly hooked when, in the Fall of 1832, he saw that endemic taxa (e.g., edentate mammals and South Ameri can rodents) showed both replacement patterns in time (the extinct glyptodonts and giant ground sloths succumbing to extinction, but still represented by modern species of armadillos and tree sloths) whereas his fossil cavy from Bahia Blanca seemed to sail right through, persisting into the modern fauna. Then, receiving Lyell's just recently published anti Lamarckian/anti-transmutational diatribe (Volume 2 of Ly ell's Principles of Geology) a few weeks later, Darwin was off and run ning: he had his own original data to compare with the wisdom of his elders. It is worthwhile to recall that Darwin had heard of transmutation from both his grandfather Erasmus' Zoonomia, and in person from the young invertebrate zoologist Robert Grant?a fan of both the elder Darwin and of Lamarck. Hard on the heels of his paleontological experiences at Bahia Blanca, Darwin quickly learned his Lamarck from Lyell, who was judicious in his sum mary of Lamarck's views even as he was scathingly opposed: Lyell was a barrister after all! From then on, Darwin was fast on his way to becoming more convinced of the likely truth of transmutation rather than creationism long before he got to the Galapagos in the late summer of 1835. Thus paleontology, at least as much as anything else, is what got Darwin there in the first place. And yet his Origin effectively gave permission to his successors to ignore paleontology in favor of the near-exclusive contemplation of variation, selection and reproductive processes in general to understand the very nature of what soon came to be called the "evolutionary" process. As George Gaylord Simpson put it in the Introduction to his brilliant 1944 Tempo and Mode in Evolution, in the minds of his "neon tological" contemporaries (he had geneticists specifically in his sights), paleontology had little more to offer than the "completed demonstration of the truth of evolution." In one of the great wry comments ever written by any evolutionary biologist, Simpson completed the thought by saying that geneticists believe that a pa leontologist is "like a man who undertakes to study the principles of the internal combustion engine by standing on a street corner and watching the motor cars whizz by." Simpson begged to differ: His entire point in the ensuing chapters was to demonstrate that patterns in evolutionary his tory characteristically repeat themselves regardless of position in time, place, or clade. The pattern he focused on was the