Jean Manco has a new book out on the peopling of Europe, Ancestral Journeys. The general picture is that Europeans arise from three main groups: the Mesolithic hunters (Hyperboreans), Levantine farmers, and Indo-Europeans off the steppe. It’s a decent synthesis of archaeological, linguistic, and genetic evidence. I suspect that her general thesis is in the right ball park: surely not correct in every detail, but right about the double population replacement.

It is a refreshing antidote to previous accounts based on the pots-not-people fad that originated back in the 1960s, like so many other bad things. Once upon a time, when the world was young, archaeologists would find a significant transition in artifact types, see a simultaneous change in skeletons, and deduce that new tenants had arrived, for example with advent of the Bell Beaker culture. This became unfashionable: archaeologists were taught to think that invasions and Völkerwanderungs were never the explanation, even though history records many events of this kind. I suppose the work Franz Boas published back in 1912, falsely claiming that environment controlled skull shape rather than genetics, had something to do with it. And surely some archaeologists went overboard with migration, suggesting that New Coke cans were a sign of barbarian takeover. The usual explanation though, is that archaeologists began to find the idea of prehistoric population replacement [of course you know that means war – war means fighting, and fighting means killing] distasteful and concluded that therefore it must not have happened. Which meant that they were total loons, but that seems to happen a lot.

But the book could be better. Jean Manco relies fairly heavily on mtDNA and Y-chromosome studies, and they are not the most reliable evidence. Not because the molecular geneticists are screwing up the sequencing, although there must sometimes be undetected contamination, but because mtDNA and Y-chromosomes are each single loci with an effective population size four times smaller than autosomal genes. They are more affected by drift, and drift can deceive you. Moreover, in some cases selection might affect the historical trajectory of mtDNA and Y-chromosomes, which would add to the confusion. Now to be fair, we have more ancient mtDNA results than autosomal DNA, and there is more published data on mtDNA and Y-chromosome than autosomal DNA in existing populations. This situation is rapidly improving.

Autosomal DNA has zillions of loci and a larger effective population size. Most of it is neutral. That’s what you want, for investigating past mixing and movement – and autosomal DNA yields interesting hints using publicly available data and software. For example, using the program ADMIXTURE, you find a West Asian-like component in almost all Europeans (from Spain to Russia, and at about the same level) – but not in Sardinians or Basques. Which must be telling us something.

In addition, she’s not bloody-minded enough. She thinks that a fair fraction of the big population turnovers involved migrants moving into areas that had been abandoned by the previous owners. I can imagine that happening in a few cases. Maybe the Greenlanders, living in an extremely marginal country for their kind of dairy farming, mostly left and/or died out before the Eskimos showed up. That is, in my dreams, because we know that the two groups fought. The Greenlanders may have been in trouble, but they didn’t just fall – Eskimos pushed. The European colonization of the New World is closer, since there was a dramatic population collapse from the newly introduced Eurasian and African diseases, but even then there was a fair amount of fighting. I’m sure that there were serious epidemics in European prehistory, but it seems unlikely they compared with the impact of the simultaneous arrival of bubonic plague, diphtheria, leprosy, malaria, measles, typhoid, and whooping cough on the Amerindians (with yellow fever and cholera for dessert).

I mean, when the first farmers were settling Britain, about 4000 BC, they built ditched and palisaded enclosures. Some of these camps are littered with human bones – so, naturally, Brian Fagan, in a popular prehistory textbook, suggests that ” perhaps these camps were places where the dead were exposed for months before their bones were deposited in nearby communal burials.” ! . We also find thousands of flint arrowheads in extensive investigations of some of these enclosures, concentrated along the palisade and especially at the gates. Sounds a lot like Fort Apache, to me.

There are some new and fascinating results about European prehistory that beg to be incorporated in a revised version of this book, for example the stuff about how the Hyperboreans contributed to the ancestry of modern European and Amerindians, but that info is so new that she could not possibly have incorporated it. Not her fault at all.

Read it.