WE HUMANS like to see ourselves as special, at the very pinnacle of all life. That makes us keen to keep a safe distance between ourselves and related species that threaten our sense of uniqueness. Unfortunately, the evidence can sometimes make that difficult.
Decades ago, when the primatologist Jane Goodall told anthropologist Louis Leakey that chimps used sticks to scoop up termites, he wrote: 鈥淣ow we must redefine tool, redefine man or accept chimpanzees as human.鈥� The news this month that humans and Neanderthals interbred (see 鈥淩evealed: the cavemen that live on in all of us鈥�) presents us with a similar conundrum 鈥� only this one lies far closer to home. Must we now consider Neanderthals as one of our own, another twig on the branch called Homo sapiens?
Svante P盲盲bo, the pioneer of palaeogenetics, equivocated when a reporter asked whether his genome study suggested Neanderthals are the same species as us: 鈥淚 would more see them as a form of humans that were a bit more different than people are from each other today, but not that much.鈥�
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Why so shy? Putting aside the vexing question of what defines a species 鈥� which flummoxed even Linnaeus and Darwin 鈥� it is hard to see why Neanderthals should now be considered as anything other than Homo sapiens. We know that Neanderthals bred with our ancestors and produced fertile offspring, which is one hallmark of a species. And there is plenty more evidence to support giving them the status of Homo sapiens neanderthalis.
Neanderthals shared a common ancestor with modern humans around 500,000 years ago. Its descendants went their separate ways as the Neanderthals adapted to colder climes, but then, at least 50,000 years ago, they resumed relations in the eastern Mediterranean, where the two populations met again. This pattern wouldn鈥檛 necessarily merit separate species status for most animals, so why for us and Neanderthals?
There is, of course, more to the concept of being human than ecology and genetics: we are human because we think, talk, love and believe. It is impossible to know the mental life of a Neanderthal, but there is reason to think that it was not so different from our own. The Neanderthal genome differed little from ours, encoding fewer than 100 changes that would affect the shape of proteins.
鈥淲e cannot know the mental life of a Neanderthal, but it may not have been so different from our own鈥�
True, some of these differences occur in genes linked to brain function, but similar variation is found among humans today. Moreover, Neanderthals share with us a version of a gene linked to the evolution of speech, and recent archaeological evidence suggests that their minds were capable of the symbolic representations that underlie language and art. If that鈥檚 not human, then what is?