Continuing Discontinuity

Local Hunter-Gatherers Obstruct Incoming Farmers, Again

In the last post, we saw that there was discontinuity in the genetic record between medieval and contemporary Tuscans. Contradictions keep popping up whenever geneticists seek to show continuity in human populations. The human facts are not obedient to scientific models. The latest example is an article titled, “Genetic Discontinuity between Local Hunter-Gathers and Central Europe’s First Farmers,” appearing in Science 326/5949:137-40 in October. The authors are B. Bramanti, M. G. Thomas, W. Haak, M. Unterlaender, P. Jores, K. Tambets, I. Antanaitis-Jacobs, M. N. Haidle, R. Jankauskas, C.-J. Kind, F. Lueth, T. Terberger, J. Hiller, S. Matsumura, P. Forster and J. Burger.

After the domestication of animals and crops in the Near East some 11,000 years ago, farming had reached much of central Europe by 7500 years before the present. The extent to which these early European farmers were immigrants or descendants of resident hunter-gatherers who had adopted farming has been widely debated. We compared new mitochondrial DNA (mtDNA) sequences from late European hunter-gatherer skeletons with those from early farmers and from modern Europeans. We find large genetic differences between all three groups that cannot be explained by population continuity alone. Most (82%) of the ancient hunter-gatherers share mtDNA types that are relatively rare in central Europeans today. Together, these analyses provide persuasive evidence that the first farmers were not the descendants of local hunter-gatherers but immigrated into central Europe at the onset of the Neolithic.

It is not often that the august personages who collaborate in the field of population genetics admit to surprise, but this study exhibits a few wavering moments of – I don’t want to say “humility,” but perhaps slight uncertainty. The main intransigence concerns the large presence of mitochondrial haplogroup U in the skeletons analyzed from Central Europe, 13,400 to 2300 BCE. Whereas these types of U are relatively uncommon in Europe today, they were the dominant population then. Germany and surrounding regions were still very much in the Stone Age. Conversely, the Neolithic types H, T and J, which were supposed to be sweeping across the hinterlands and introducing agriculture from the Middle East (along with a characteristic pottery called Linearbandceramik, German for “linear band ceramics,” or LBK) were evidently thin on the ground and held their distance. Nowhere did the twain meet, for “we found no U5 or U4 types in that early farmer sample. Conversely, no N1a or H types were observed in our hunter-gatherer sample, confirming the genetic distinctiveness of these two ancient population samples.” In other words, even the entrenched types of populations living as neighbors, U and N1a, were not mixing with each other.

Clinging stubbornly to the “classic model of European ancestry components (contrasting hunter-gatherers with early Neolithic farming pioneers),” the authors explain away the facts in simplistic fashion. With breath-taking generalizations, they assume, and then prove, that the “U types in our hunter-gatherer samples [and their not mixing with the other haplogroups]…extend beyond the local scale.” Do they forget that a study they wrote in the same journal four years ago found a predominance of N1a in skeletons in the same region and time? (see Wolfgang Haak, Peter Forster, Barbara Bramanti, Shuichi Matsumura, Guido Brandt, Marc Tänzer, Richard Villems, Colin Renfrew, Detlef Gronenborn, Kurt Werner Alt, and Joachim Burger, “Ancient DNA from the First European Farmers in 7500-Year-Old Neolithic Sites,” Science 11 November 2005: Vol. 310. no. 5750, pp. 1016 – 1018.)

As T.S. Eliot said, “My end is in my beginning.” Thus, the venture ends where it began, with the assumption that there is but one compelling story to be told in Europe for thousands of years after about 6,000 BCE, and that is the triumphal march of agriculturalists across the genetic landscape. With false humility, the authors conclude, “The extent to which modern Europeans are descended from incoming farmers, their hunter-gatherer forerunners, or later incoming groups remains unsolved.” But circular reasoning is circular reasoning even if it does not beget a strong conclusion.

All such studies presume a starlike and gradual diffusion of people. Hence, they expect to see broad patterns of continuity in time and space. Unfortunately, human history is fraught with disjoint as well as discontinuous phenomena. The ant farm models of population genetics cannot begin to comprehend the complexity of the past or do it justice.

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