The Atheist News Podcast

There has, over the centuries since Darwin posited his theory of natural selection–and, more specifically, of the descent of man from early ape ancestors–been much wailing and gnashing of the teeth.  One of the more frequently wailed notes (translated into language that can be understood by reasonable people) goes something like this: if Darwin was right in even the broad strokes about the origin of humanity, where are all the links between our old-world ape-like ancestors and modern humans?  Why, that is, don’t we see more fossil records of things that look not quite human, but not quite ape-like either?  Discounting the fact that there are a multitude of such forms on record already, where (the wailers say) are our early hominid fossils?  Where, that is, are our Bigfoot fossils?

There are a lot of reasonable answers on record to this.  Even Darwin recognized what he called the “problem of transitional species” in the Origin of Species, and he went out of his way to address it: “[W]e should bear in mind that animals displaying early transitional grades of [any given] structure will seldom continue to exist to the present day, for they have been supplanted by the very process of perfection through natural selection.  [...] Hence the chance of discovering species with transitional grades of structure in fossil condition will always be less, from their having existed in lesser numbers, than in the case of species with fully developed structures” (this is near the middle of chapter five, page 209 in the 2003 edition of the Origin of Species edited by Joseph Carroll).  Darwin’s response to this objection raises a few philosophical problems–perhaps chiefly, it leads us naturally to ask what the hell he means by “perfection through natural selection”–but, I think, the core of his resolution rings true.  Fossilization is an extraordinarily rare phenomenon: it requires precisely the right conditions (rapid burial in sediment) that just don’t obtain very often, at least considering the number of organisms that might be fossilized.  This seems particularly true for even the early hominids, which might well have had the resources to avoid such burials in ways that other animals wouldn’t have been able to take advantage of.

Those points aside, it looks like there’s yet another link in the chain.  Wired reported yesterday on a recent discovery of another early hominid skeleton.  This one predates the previous record holder–Lucy–by at least one million years, and suggests that the line of species that eventually led to humanity originated in the forests rather than the Savannah, as previously thought; the new fossil, which the scientists have named “Ardi,” had thumb-like toes for climbing, walked upright, and had a thick coat of fur.  The artist’s rendition in the Wired article looks suspiciously like the paradigmatically “missing-link” Big Foot.  Perhaps more interesting than the physical features, though, are the hypothesized cultural features that Ardi might have shared with us: based on tooth and jaw structure, the evolutionary anthropologists have postulated that Ardi and her species lived together relatively peacefully, had a cooperative social structure, and generally lived more like humans than like chimpanzees, which have a relatively violent society.  This suggests that our cultural evolution may have been as important in the history of our species’ development as our physical evolution–indeed, the two may be closely linked.

In any case, this is just another piece of evidence for the evolution of man, not that the theory needed any more bolstering.  Any bets on how long it will take for a creationist to point out that now there are two more transitional forms required?