Tuesday, 14 February 2012

Let Me 'splain Somethin' to You 'bout John Hawks, Svante Pääbo, and You, Lucy

I suppose I should just come out and say it, since there's no point in being coy. The now-irrefutable evidence that you and I share varying amounts of apomorphic genetic material with the Neanderthals does nothing to settle the question of whether or not the Neanderthals and we might have, could have, would have, or should have had offspring together. 
     No good. 
     And here's why.
     For a moment, put aside whatever 'feelings' you may have about the Neanderthals' cognitive abilities compared with those of you and me. 
     About 100,000 years ago, at Qafzeh Cave, there are skeletally modern humans. A geological minute later there are Neanderthals a few km down the road at Kebara Cave. These two morphotypes may never have set eyes on one another. But the overlap in their territories, whatever the reason, means that there's at least a good chance they bumped into one another. Which means that if they recognized each other as potential mates the strong likelihood is that they did the wild thing and had families.
     You can slice it and dice it, split hairs, and argue 'til you're blue in the face, but the archaeological traces associated with each of these two species leads to the  robust inference that they behaved in the same manner. They produced Mousterian assemblages at each site, with a Levallois facies. If we had never found the skeletal remains at Kebara or Qafzeh, we archaeologists would no doubt have reached the same consensus--that those traces were left by hominids that were, more or less, behaviorally and cognitively identical.
     As you're no doubt painfully aware by now, I have strong reservations as to the abilities of the Neanderthals, based on my 'reading' of the archaeological record. And, those of you familiar with my three (Yep, 3) solo publications will know that, when I speak of the cognitive abilities of the Neanderthals I'm also speaking of morphologically modern, but archaeologically identical, penecontemporaneous hominids such as those at Qafzeh. What many of you don't know is that, if asked, I would also include Homo sapiens idaltu, at 160,000 kya and any other shape of hominid that left a similar archaeological record, regardless of their epoch. 
     I'm an archaeologist with a deep knowledge of evolution, human and otherwise. I'm also equipped with a modicum of knowledge in comparative vertebrate paleontology, geomorphology, pedology, animal bone identification, interpreting animal bone from archaeological sites, vertebrate taphonomy, site formation processes, lithic analysis, and informal logic. But I'm still just an archaeologist when it comes to the Middle Palaeolithic. 
     And, until such time as it's possible to say that Broca's Area unequivocally demonstrates that the owner possesses the ability to read this blog, or that we're able to say that the FOXP2 gene unequivocally demonstrates that its owner possesses a similar ability, all that remains for anyone to use in understanding the abilities of those ancient hominids is the archaeological record. 
     Archaeologists are uniquely placed to interpret ancient behaviours from archaeological traces. Anatomists cannot. Vertebrate palaeontologists cannot. Geomorphologists cannot. Sometimes I really wonder if lithic analysts can. I am profoundly aware that my expectations and presuppositions of Neanderthal behaviour can clutter and colour my perceptions. That's why I concentrate so heavily on the physical evidence and its context, because that's the only way to move past my expectations in understanding the cognitive abilities of Middle Palaeolithic hominids.
     Along the way, if I find knowledge claims that don't stand up, or represent, merely, one alternative explanation for the archaeological traces under examination, I'm compelled to point that out. There are so many extraordinary claims in the literature of the Middle Palaeolithic that it would takes decades of work like mine to really put the feet to the fire of those who've come before. I simply can't stand by while the real howlers are allowed to remain in the archaeological corpus. 
     And you're here to observe me at it. 
     So, to get back to the genome data. I'm in awe of the biochemical wizardry that John Hawks, Svante Pääbo, and their extremely adept colleagues are demonstrating. Yet, their documentation of the degree of relatedness between modern humans and the Neanderthals, or the Denisovans, means only that we share a common ancestor with the ancestors of those groups
     I'm very proud to say that it's still up to the archaeologists, and they alone, to decide which Middle to Late-Pleistocene hominid morphotype or population gave rise to people like us, and when that occurred. As it was before the 1000 genome data became available, when it comes to Middle Palaeolithic hominid behaviour we have a lot of work to do before we've investigated every alternative explanation for each and every extraordinary claim that's made about that distant time.
     I'm gonna go back to that task now.