Krieg als Grund für relativ gleiche Y-Chromosomen

Ein interessante Studie nimmt an, dass Krieg dazu geführt hat, dass das Y-Chromosom keine sehr große Vielfalt hat.

Aus der Studie:

In human populations, changes in genetic variation are driven not only by genetic processes, but can also arise from cultural or social changes. An abrupt population bottleneck specific to human males has been inferred across several Old World (Africa, Europe, Asia) populations 5000–7000 BP. Here, bringing together anthropological theory, recent population genomic studies and mathematical models, we propose a sociocultural hypothesis, involving the formation of patrilineal kin groups and intergroup competition among these groups. Our analysis shows that this sociocultural hypothesis can explain the inference of a population bottleneck. We also show that our hypothesis is consistent with current findings from the archaeogenetics of Old World Eurasia, and is important for conceptions of cultural and social evolution in prehistory.

Quelle: Cultural hitchhiking and competition between patrilineal kin groups explain the post-Neolithic Y-chromosome bottleneck

Aus einer Besprechung der Studie:

„Instead of ’survival of the fittest‘ in a biological sense, the accumulation of wealth and power may have increased the reproductive success of a limited number of ’socially fit‘ males and their sons,“ computational biologist Melissa Wilson Sayresof Arizona State University explained at the time.

Tian Chen Zeng, a sociologist at Stanford, has now built on this hypothesis. He and colleagues point out that, within a clan, women could have married into new clans, while men stayed with their own clans their entire lives. This would mean that, within the clan, Y chromosome variation is limited.

However, it doesn’t explain why there was so little variation between different clans. However, if skirmishes wiped out entire clans, that could have wiped out many male lineages – diminishing Y chromosome variance.

Computer modelling have verified the plausibility of this scenario. Simulations showed that wars between patrilineal clans, where women moved around but men stayed in their own clans, had a drastic effect on Y chromosome diversity over time.

Also ein Modell, bei dem Männer Kriege führen, die Frauen als „Beute“ mitnehmen und dann an die mit Status etc verteilen. Ähnliches kennt man beispielsweise aus den Sagen um den trojanischen Krieg, aber auch sonst waren Frauen in vielen früheren Kriegen Beute, die dann an die mächtigeren verteilt worden sind, die so ihre Gene verteilen konnten.

 

 

Y-Chromosome Verteilung

Y-Chromosome Verteilung

Male-specific Y (MSY) chromosome phylogeny from next-generation sequencing data, and associated demographic reconstruction. a MSY phylogeny based on 456 samples and 35,700 SNPs. Major haplogroups are labelled. The orange box highlights recent expansions identified in several haplogroups, and the yellow box highlights more ancient expansion of deep-rooting lineages. b MSY Bayesian Skyline Plots (of effective population size against time), with different world regions indicated by colours as shown in the key. Reprinted from Batini and Jobling78 with permission from Mark A. Jobling and Springer Science+Business Media

 

Natürlich belegen Simulationen nicht, dass es so war, aber die Daten sind dennoch interessant.

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