San Francisco Chronicle -- October 31, 2004
The Ancestor's Tale: A Pilgrimage to the Dawn of Evolution
by Ian Garrick Mason
Houghton Mifflin, 673pp, $28.00
Quite naturally, it was difficult for people living in the 19th and early 20th centuries to accept the idea that human beings descended from apes. Like others born in the later 20th century and well away from the Bible Belt, I've always been comfortable with the notion -- all those childhood books about dinosaurs and fossils, I suppose -- but even I was taken aback to learn that human beings also share a common ancestor with bread mold.
Richard Dawkins commonly has this sort of effect on readers. In The Selfish Gene (1976), for example, he introduced the astounding concept that humans don't use genes to reproduce, genes use us -- that we humans are merely "survival machines" for preserving self-interested molecules. Dawkins' way is to take a theory that has achieved a fuzzy sort of general acceptance and to rigorously argue it out until the theory and all of its logical ramifications stand naked in the light, and readers are left blinking.
In The Ancestor's Tale, Dawkins' aim is to take the reader step by step from modern man back through every single one of our biological ancestors to the origin of life itself. He visualizes this as a Chaucerian pilgrimage, a Canterbury Tales of evolution, in which modern species are fellow pilgrims who meet us at the "rendezvous" points where they originally split away from our own evolutionary branch (or, one might also say, where we split away from theirs). Our first meeting is with chimpanzees and bonobos at roughly 6 million years in the past; walking together, we are joined by the gorillas at 7 million years. This process continues back through the eons, through mammals and birds, amphibians and fish, insects and sponges, fungi and plants -- until finally we meet the common bacterial ancestor of all life on earth.
And as in Chaucer, these pilgrims have tales to tell, which Dawkins uses to illuminate evolutionary themes and questions. Theories about the emergence of bipedalism, for example, are explored in the section "Little Foot's Tale" ("Little Foot" is a recently discovered early hominid skeleton, even older than the now famous "Lucy"). "The Duckbill's Tale," meanwhile, undercuts the idea of primitiveness. "Platypuses have had exactly the same time to evolve as the rest of the mammals," he points out; if a species retains its characteristics over a long span of time, it is because those characteristics work.
Conversely, those characteristics that don't work, or for which an animal has little use, disappear: "The Dodo's Tale" illustrates the process by which pigeons landed on a remote island and, finding no predators, eventually lost the ability to fly. Ironically, the flightless dodo would prove defenseless against the clubs of Portuguese sailors. Should dodos have preserved their wings, just in case they were needed again? "Alas (for the dodo) that is not the way evolution thinks. Evolution doesn't think at all, and certainly not ahead." Which is a main reason why Dawkins chooses a backward pilgrimage: It's the only direction with any "meaning" to it. Going forward from the origin of life could lead literally anywhere, along any branch to any modern species. Humans cannot consider themselves the sole endpoint of the process, after all: "A historically minded swift," he points out, "understandably proud of flight as self-evidently the premier accomplishment of life, will regard swiftkind ... as the acme of evolutionary progress."
In explaining the processes of evolution, natural selection and genetics, and more important, the scientific methodologies that have discovered and described these processes, Dawkins reveals some very complex machinery indeed. Yet he does so with his traditional clarity: Under his pen, logarithms are comprehensible and useful tools, DNA is reconceived as a library of subroutines rather than as a hyper-detailed blueprint, and radioactive dating is a simple matter (in principle) of comparing half-lives in rocks. But Dawkins has a seriousness of purpose, and he is writing for those who really want to understand the science. So there are a few sections -- like "The Gibbon's Tale" about rooted and unrooted cladograms, phylogenetic trees and Bayesian analysis -- which may force the layperson to either re-read until the concept is clear or to skim to the next section.
But understanding the complexity is worth the effort, for it is Dawkins' convincing portrayal of life's interrelations, of its grand cousinage, that is perhaps the most deeply affecting aspect of the book. Its sense was expressed well by William Golding, author of Lord of the Flies, who in his 1983 Nobel Prize acceptance speech made a riveting plea for the environment. Describing his childhood discovery of a deep tidal pool teeming with forms of unknown life, he said, "I can remember and even feel [the] passionate recognition of a living thing in all its secrecy and strangeness. It was, or rather they were, real as I was. [...] Only a hand's breadth away in the last few inches of still water they flowered, gray, green and purple, palpably alive, a discovery, a meeting, more than an interest or pleasure. They were life, we together were life itself; until the first ripples of returning water blurred and hid them."