Chris Stringer: Meet the Relatives

Chris Stringer has a post in the Financial Times titled Meet the Relatives.  It is sort of a whirlwind tour through the evolution of the genus Homo.    He writes:

The discoveries of Homo floresiensis, Homo luzonensis, Denisovans and Homo naledi in the past 15 years remind us that the fossil record of humans is still very patchy — stone tools are scattered across much of Africa as a witness to widespread human occupation, yet fossil evidence has been recovered from less than 10 per cent of that continent’s area.

The percentage coverage for Asia is hardly any better: there is, for example, currently only one significant human fossil from the whole of the Indian subcontinent. The discoveries of the past few years underline just how much evolutionary history remains unknown, with other extinct lineages no doubt still to be revealed.

Many of the new finds challenge how we classify fossils in relation to Homo sapiens today. I continue to call the Neanderthals a different species from us, based on their distinctive skeletons and skulls; others feel that the recent evidence of interbreeding and increasing evidence of sophisticated behaviour mean that we should merge them, and the Denisovans, into our species.

I think that the discovery of the Xuchang hominins indicates that there has been considerable population mixing for several hundred thousand years.  As I wrote at the time:

These two Chinese skulls stand at the crossroads of these population movements. While showing clear Neandertal characteristics, they also express modern traits, possibly reflecting mixing with the late, modern human arrivals represented by the recent modern human finds at Daoxian. Yet they also express a clear link to ancient East Asian populations. The implications of these skulls are stark: there has been widespread population mixing and regional continuity in Europe and Asia for at least 400 thousand years. Not only did the Neandertals feel enough cultural kinship to mate and have children with these East Asian people, the early modern humans coming out of Africa did, as well. As Chris Davis of China Daily News put it: “One big happy family.”

Whether this represents such behavior at the peripheries of different species or that of one polytypic species is, as yet, unclear.  It is very clear that our understanding of how these populations interacted is rudimentary, at best.