John Shea is a professor of anthropology at Stony Brook, specializing in ancient archaeology. He’s been making the argument that ‘behavioral modernity’ is a flawed concept, which it is. Naturally, he wants to replace it with something even worse. Not only are all existing human populations intellectually equal, as most anthropologists affirm – all are ‘behaviorally modern’ – all past populations of anatomically modern humans were too! The idea that our ancestors circa 150,000 B.C. might not be quite as sharp as people today is just like the now-discredited concept of race. And you know, he’s right. They’re both perfectly natural consequences of neodarwinism.

Behavioral modernity is a silly concept. As he says, it’s a typological concept: hominids are either behaviorally modern or they’re not. Now why would this make sense? Surely people vary in smarts, for example: it’s silly to say that they are either smart or not smart. We can usefully make much finer distinctions. We could think in terms of distributions – we might say that you score in the top quarter of intelligence for your population. We could analyze smarts in terms of thresholds: what is the most complex task that a given individual can perform? What fraction of the population can perform tasks of that complexity or greater? Etc. That would be a more reasonable way of looking at smarts, and this is of course what psychometrics does.

It’s also a group property. If even a few members of a population do something that anthropologists consider a sign of behavioral modernity – like making beads – everyone in that population must be behaviorally modern. By the the same argument, if anyone can reach the top shelf, we are all tall.

The notion of behavioral modernity has two roots. The first is that if you go back far enough, it’s obvious that our distant ancestors were pretty dim. Look at Oldowan tools – they’re not much more than broken rocks. And they stayed that way for a million years – change was inhumanly slow back then. That’s evidence. The second is not. Anthropologists want to say that all living populations are intellectually equal – which is not what the psychometric evidence shows. Or what population differences in brain size suggest. So they conjured up a quality – behavioral modernity – that all living people possess, but that homo erectus did not, rather than talk about quantitative differences.

The idea of behavioral modernity (as usually stated) makes no sense. Ongoing adaptive evolution changed people. Upon expansion out of Africa, admixture with archaics added quite a bit of new adaptive variation. That changed people – some of them. Anatomically modern Africans mixed with other archaic populations inside Africa, populations that were more different than Neanderthals, having diverged something like a million years ago – and that changed them. New tools, new cultural innovations – above all agriculture – changed the selective pressures, and people changed again. Culture influenced mutation rates as well. You don’t expect to see sameness in either space or time – and we don’t.

Shea seems to think that a species – in particular, anatomically modern humans – is some kind of Platonic type and has an unchanging essence. So if all humans are ‘behaviorally modern’ today (they have to be, whether they are or not), surely they were 200,000 years ago as well. Those Australians are just pretending to have 15% smaller brains, while the Ashkenazi Jews are just pretending to be smart. S. J. Gould seems to have thought along these same lines, to the point where he would argue with someone (Reznick) who found that a few generations of different selective pressures (no predators above waterfalls) caused heritable changes in guppy behavior. Gould disliked anything that suggested that selective pressures could result in human behavioral differences. Since everything suggests that, he kept busy. But archaeologists often get their evolutionary theory from Gould, not knowing that he was a lying jackass.

If the inner nature of a species stays always the same, where did anatomically modern humans come from in the first place? Were they found under a cabbage leaf?

Does Shea think that canines have an unchanging essence, so that Pekingese and border collies and timber wolves are all really the same? They really are different. I will stick my hand into a Labrador’s mouth if Shea puts his hand into a pit bull’s mouth. Take a look at canine venereal sarcoma (yuck!) – once a dog, now an infectious cancer. Where’s the essence?

Shea says that no anthropologist in his right mind would think that existing cultural variation among humans had anything to do with genetic differences between existing populations. It will be interesting to discover the alleles that made him say that.