Ardi Comes to Town!

Well, actually it was Tim White who came, to talk about Ardi. It was a pleasure to see his impressive pictures of the Awash Valley of Ethiopia, where the fossilized bones of Ardi and so many other species were found, as well as to hear his description of the truly painstaking work it was over 15 years to piece together the parts of the skeleton they have, and to catalog all the other fossils they found over many field seasons.

And it was fascinating to get a glimpse into the passion that drives White's life's work. As he pointed out, in The Descent of Man, in an often cited passage, Charles Darwin is frequently read as predicting that human progenitors originated in Africa.

In each great region of the world the living mammals are closely related to the extinct species of the same region. It is therefore probably that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee; and as these two species are now man’s nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere.

Though some scholars quibble with how prescient Darwin really was about human origins here, given the lack of fossil evidence at the time, White clearly seems to feel that he is a direct intellectual descendant of Darwin's, rising to the challenge Darwin laid down so long ago. The man of vision is there by his side as Tim scours the earth for our early ancestors in the Awash Valley.

White has a deep appreciation for his finds as important pieces of world heritage, as well as for their value as direct confirmation of Darwin's prediction. Of course, as he also said, we don't need the fossils to know that our closest ancestors lived in Africa and to know something about the time it has taken to make us from them; DNA sequence data have long ago settled that to within a reasonable approximation.

In his talk, Tim finished up by listing a number of ideas of Darwin's about human origins that have turned out to be true, supported by the fossil evidence (which he also discusses in an essay on the National Science Foundation website honoring the 150th anniversary of the publication of the Origin).

But Darwin's predictions about inheritance are much less au courant in molecular biology because he was so wrong about so much, and the field has come so far in 150 years (and in fact, Ken also has written an essay that appears on the NSF site, where he chips away a bit at the often rather uncritical Darwinian ancestor-worship). This is in no way to detract from Darwin, who set the research stage for the biologists who followed him, even where he was wrong, or making wild guesses (which he did quite a lot of).

Darwin recognized the importance of inheritance (as had some of his predecessors as well as Wallace), but his ideas were very wrong and much more conventional than the usual image of Darwin-the-pathfinder. We know a lot better today, and it's possible to recognize Darwin's fundamental insights -- common origin, life as history, and natural selection as a force (given the right conditions), and nothing yet discovered by biology contradicts these facts of life -- while also recognizing where he was wrong. It's important to do that, because otherwise the Origin of Species can morph into an equivalent of the Bible, and that would not be good for science.

Darwin is still treated by many molecular biologists as having the same kind of driving presence as Tim White the paleontologist seems to feel he has, however. But that is a rather careless view that rests on assumptions about natural selection as an all-powerful force, and the inference, without really reading him carefully or looking at data critically, that Darwin's was The Word.

That reservation aside, it was still nice to hear that as Tim trudges over the blistering sands of Ethopia, he feels Darwin watching over his shoulder.