Thursday, March 25, 2010

New Hominid Species?

Well, no. Like those questions that form the titles of articles in so much of our supposedly serious press, the answer is no. The paper doesn't talk of species, but form and lineage, and for a very good reason- there isn't enough difference in the mtDNA genome to be sure that it is more than a highly divergent eastern population of Neanderthal.

The story (behind a paywall) is discussed here, here, here, here, and here by people who mostly know what they're talking out.

The region of the Altai mountains where it was found was also home, at a similar time-depth (around 40,000 years) to modern humans and Neanderthals, and it came as a great surprise to Svante Pääbo and the team, because they had assumed it was just one more Neanderthal bone. 'It', by the way, is a single distal palanx, that is the tip, of a little finger, and it seems to be impossible to do any meaningful morphological analysis in order to learn about the phenotype of the creature it came from. But enough unadulterated DNA has been recovered to do the sequencing, and in the near future they hope to sequence the entire nuclear genome, too, which will provide a lot more information.

What does it mean? Did an unknown hominin leave Africa at an unknown time and evolve into something that we have only just discovered? Did it evolve from a known species of Homo, in a previously unrecorded exodus? How similar was it to Neanderthals and humans? Insofar as these questions can be answered at the moment, the answers will be found in the links.

So many gaps exist in our knowledge of hominid evolution (in fact it consists almost entirely of gaps, with random islets of information strewn over a vast ocean of total, and possibly permanent, ignorance. Finds usually come about by chance, and in many regions, including much of Africa, the geology is such that the likelihood of recovering anything from them is almost zero) that any new discovery is likely to require a big restructuring of our entire understanding of the matter. This bone has not quite put us in that position, but the nuclear DNA sequence may well do.

Palaeoanthropolgy is a science and, as such, it collects data, formulates hypotheses and detemines ways by which these might be tested, new data obtained and so the hypotheses rejected or refined. The usual caveats apply, concerning the limits of human nature, the weakness, pride, complacency and stupidity to which it is prone, but there is behind it all a well tested system for approaching the truth. The problem with the field, as I suggested above, is that the data become available rarely and randomly, and it is impossible to design experiments or to test hypotheses unless new data happen to emerge by chance which are more or less what was needed. It makes the search for truth a deeply frustrating one, and it means that every new site, or even a new bone, that appears, may show the previous, tentative but painstakingly constructed chronology to be false.

It is highly unlikely that we will ever know the full story of human evolution, but we have just learned something else, which might, one day, help us to understand a bit of the story, rather than being a few random syllables from a seemingly unconnected chapter.

It is a search I find endlessly fascinating, not only in itself as a constantly changing field of science, full of important surprises, but also because I, at least, am interested in it in part in order to get a clearer, fuller idea of what it means to human. To know something more of where we came from, and how, and what we might have been, is to have a better understanding of yourself. I think it matters, or perhaps I just find it interesting.

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