Friday, July 21, 2006
Lessons from Supposed Anglo-Saxon Apartheid
An interesting study by Dr Mark Thomas et al., of the University College, London, Department of Biology et alia, suggests that, “The native Britons were genetically and culturally absorbed by the Anglo-Saxons over a period of as little as a few hundred years." A UCL press release on the research can be found here.
The study, which appears in the recent edition of the Proceedings of the Royal Society B: Biological Sciences, attempts to reconcile historic and archeological evidence for a limited incursion of Anglo-Saxons during their invasion and occupation of Britain, with genetic evidence showing the wholesale replacement of indigenous Celtic Y-chromosomes with those derived from a continental German substrate. As the article's abstract states:
The role of migration in the Anglo-Saxon transition in England remains controversial. Archaeological and historical evidence is inconclusive, but current estimates of the contribution of migrants to the English population range from less than 10000 to as many as 200000. In contrast, recent studies based on Y-chromosome variation posit a considerably higher contribution to the modern English gene pool (50–100%). Historical evidence suggests that following the Anglo-Saxon transition, people of indigenous ethnicity were at an economic and legal disadvantage compared to those having Anglo-Saxon ethnicity. It is likely that such a disadvantage would lead to differential reproductive success. We examine the effect of differential reproductive success, coupled with limited intermarriage between distinct ethnic groups, on the spread of genetic variants. Computer simulations indicate that a social structure limiting intermarriage between indigenous Britons and an initially small Anglo-Saxon immigrant population provide a plausible explanation of the high degree of Continental male-line ancestry in England.While interesting in and of itself, the study highlights that rapid genetic replacement can occur when two populations come into sustained contact, with hard to document demographic factors leading to fundamental shifts in the genetic composition of descendent populations.
This has a direct bearing on the controversy surrounding the role of Neanderthals in the descent of modern Europeans. My previous post hails the announcement that a concerted attempt has been initiated to completely decode the Neanderthal genome. This will eventually allow scientists to determine with certainty the contribution, if any, that Neanderthals made to modern European populations.
No matter what the ultimate outcome of these future studies may be, the issue of genetic replacement must take into account demographic factors such as those discussed in the research described above. There is no question that modern humans replaced the more archaic Neanderthal population of Europe in a relatively short span of time (~ 8000 year). The dynamics of this replacement are still debated and should be the focus of future research (see here, abstract A28 for example). Less emphasis should be placed on subjective questions of whether or not Neanderthals were a separate species of humankind.