|'Red Deer Cave Man'|
From Longlin cave in Guangxi province, China.
Photograph: Darren Curnoe
A team of Chinese and Australian palaeoanthropologists recently announced the discovery of hominid remains in a couple of sites in South China which "... are unlike recent populations of modern humans in several respects, and the mosaic of more archaic features could indicate the dispersal of a poorly known and more primitive form of modern human that left Africa before the main exodus at about 60,000 years. This dispersal could have reached as far as China, surviving there for many millennia, before disappearing in the last 12,000 years."
A Guardian article about this discovery can be read here.
These remains have been dated using both carbon dating and uranium-thorium dating to be between 11,500 and 14,300 years old.
The difficulty now is determining how and where these people fit in the Homo branch of the evolutionary tree. I recently blogged about the difficulty taxonomists face when trying to fit archaic specimens into a taxonomic system designed primarily for classifying living organisms. See "Where Creationists Get Confused".
These undoubted humans lived at a time when fully modern Homo sapiens lived to the south and east of their known range and had already developed agriculture, and yet they may not have interbred with them. This would imply a different species incapable of interbreeding successfully.
They may represent a mixture of features from 'Denisovans' (a recently discovered population from Central Asia who were probably close to Neanderthals and whose DNA shares features exclusively with people of Southeast Asia and Australasia) and modern humans, suggesting that they could be a population derived from hybrids or simply a later form of Denisovans. This would imply that Denisovans were themselves a subspecies of Homo sapiens or even just a regional variety.
They could conceivably be a remnant population of Homo erectus from an earlier migration out of Africa, descendants of the so-called 'Peking man' or Homo erectus pekinensis, or a remnant population of a migration out of Africa of an earlier form of Homo sapiens which then evolved in relative isolation in Asia before finally dying out about 11,500 years ago. The question then is whether they had diversified far enough to be a distinct species, whether they attained sub-specific status or, again, were only a regional variety.
They could even be evidence of a cline or 'ring species' of human varieties, species and subspecies, such as can form when a genus is spread over a wide geographical range or where isolating geographical features split up the populations, but that's perhaps more speculative.
DNA evidence, if any DNA is found, would go some way to answering this question but the problem would still remain how to classify them exactly, and so name them according to the rules of Linnaean taxonomy, but one fact stands out from these findings, as with other findings of hominid fossils: humans evolved. This is the most vicarious explanation and the only one not requiring inexplicable magic, miracles and other invocations of arbitrarily assigned supernatural entities.
The abundant remains of a now extinct Red Deer found with these hominid remains also begs an intriguing question: did these people cause the extermination of this species of deer, and/or did it's extinction cause their disappearance?
And so one small scientific discovery or new piece of information can open up a whole new list of questions and so expand the sum total of human knowledge. The new piece of information is slotted into the body of knowledge which is adjusted accordingly. Sometimes whole areas need to be adjusted or, in the popular imagination, "the science books will have to be re-written". As always, the facts are sacred and the question is what conclusions can we draw from them.
Contrast this to religion which already 'knows' the answer to all these questions but needs to ignore the fact that the 'answer' doesn't fits the evidence and is not supported by it. For example, the notion of a creator god creating modern humans fully formed as a special creation is entirely at odds with the evidence, which shows that humans evolved and diversified slowly over time, and that there were probably several species of Homo co-existing in different parts of the world, or even living side by side, for much of human history.
What will be interesting is how creationists deal with this new scientific information in order to retain their belief in special creation in situ. The normal response to these things can include:
- Claiming the fossils are fake/not hominim/diseased/deformed.
- Pointing out 'all the previous hoaxes and false claims'.
- Ridiculing the dating methods.
- Attacking those who made the discovery.
- Ignoring the new evidence altogether.
One thing you will never see is creationist re-writing their books because, to a creationist, the conclusion is sacred, not the facts. Nothing can be allowed to alter their sacred book, not even evidence.
[Update: 20 March 2013]
How quickly science changes and progresses.
In the little over a year since I wrote the above, palaeoanthropologist and geneticists have made huge progress in sequencing not only the Denisovan genome but that of Neanderthal too. It was quickly found that Denisovans not only did interbreed with Homo sapiens but that several modern people in South-East Asia and the Pacific have varying amounts of their DNA. Svante Pääbo's group at the Max Planck Institute have now sequenced Neanderthal DNA from a toe bone and we now know that 1-4% of extra-African peoples' DNA is from Neanderthals. Hence, there is little doubt that an early hominid, probably H. heidelbergensis, spread out of Africa and initially diversified in Euro-Asia into H. neanderthalensis and "Denisovans" while H. heidelbergensis evolved into H. sapiens in Africa before a second expansion out of Africa of people who were able to interbreed successfully with their close kin already occupying Europe and Asia, forming what may have been a 'ring species'. I have blogged about this in A Human Ring Species?.