Genghis Khan spread his seed so liberally that nearly a tenth of men now living in the former Mongolian empire trace their ancestry back to the 13th-century warrior. However, a new analysis suggests that most socially dominant males contribute no more to the genetic pool than do their supposed inferiors.
鈥淎n individual really doesn鈥檛 have the opportunity to set up things so their genetic information pervades the gene pool a long time in the future,鈥� says mathematician , of the University of Arizona in Tucson. 鈥淚t could happen because life is chaotic.鈥�
Theories on how genes flow through populations of organisms generally support this idea, which has been dubbed neutrality. But some anthropologists argue that cultural dominance can seal a man鈥檚 legacy. For instance, a rich and powerful father can ensure the status of his sons and grandsons.
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Back in time
To determine whether dominance could last more than a couple generations, Watkins and a team of anthropologists and geneticists sifted through the DNA of 1269 males from 41 Indonesian communities.
They honed in on stretches of the male-inherited Y chromosome that change little from generation to generation. This allowed Watkins鈥� team to peer back more than 3000 years.
Their search paid no attention to genetic traits that might offer an evolutionary boost and instead focused on 鈥渏unk鈥� DNA that flows exclusively from father to son.
Out of 41 communities, from Bali to Borneo to mainland Indonesia, only five showed evidence of long-term dominance by a few male lines.
Three of those communities were in Sumba, a remote island where males are polygamous and clans vie for status and resources. The genetic patterns seen in males from the other two communities could be explained by an influx of foreign workers in one case, and a recently settled village in the other.
鈥楨qual opportunities鈥�
Of course, Genghis Kahn proves that some powerful males can ensure their lineage 鈥� if not through prosperity, then promiscuity 鈥� but such men are rare, Watkins says.
鈥淚f I were to take 100 random Mongolians and follow their family lines, I wouldn鈥檛 have seen anything special.鈥�
, a population geneticist at Stanford University, agrees that cultural traits that flow exclusively from father to son, such as wealth and property, are unlikely to last.
鈥淓volution is an equal opportunity system. No single group is going to persist as the dominant group for very long before something changes,鈥� says , a co-author of the study.
Wars, climate change, and diseases have all sent dominant males careening off their pedestals, he says.
Journal reference: (DOI: 10.1073/pnas.0710158105)
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