Literally hundred of thousands of people have read my post, 1 in 200 men direct descendants of Genghis Khan, since 2010. It was based on the paper The Genetic Legacy of the Mongols*, which reported that one particular Y chromosomal lineage was very common in Central Asia, and, that it exhibited hallmarks of explosive growth over the last thousand years.
A new paper suggests that this inference is wrong, Whole-sequence analysis indicates that the Y chromosome C2*-Star Cluster traces back to ordinary Mongols, rather than Genghis Khan:
The Y-chromosome haplogroup C3*-Star Cluster (revised to C2*-ST in this study) was proposed to be the Y-profile of Genghis Khan. Here, we re-examined the origin of C2*-ST and its associations with Genghis Khan and Mongol populations. We analyzed 34 Y-chromosome sequences of haplogroup C2*-ST and its most closely related lineage. We redefined this paternal lineage as C2b1a3a1-F3796 and generated a highly revised phylogenetic tree of the haplogroup, including 36 sub-lineages and 265 non-private Y-chromosome variants. We performed a comprehensive analysis and age estimation of this lineage in eastern Eurasia, including 18,210 individuals from 292 populations. We discovered that the origin of populations with high frequencies of C2*-ST can be traced to either an ancient Niru’un Mongol clan or ordinary Mongol tribes. Importantly, the age of the most recent common ancestor of C2*-ST (2576 years, 95% CI = 1975–3178) and its sub-lineages, and their expansion patterns, are consistent with the diffusion of all Mongolic-speaking populations, rather than Genghis Khan himself or his close male relatives. We concluded that haplogroup C2*-ST is one of the founder paternal lineages of all Mongolic-speaking populations, and direct evidence of an association between C2*-ST and Genghis Khan has yet to be discovered.
The primary aspect here seems to be pushing the age back. The Mongols, or what became the Mongols, were a marginal group of tribes when this variant arose. There is some citation of the fact that some putative descendants of Genghis Khan don’t even carry the “Star Cluster”, but there are other papers which report even different haplotypes! So I’m not sure that that is dispositive in any sense.
Perhaps the true question now is why this cluster expanded so much over the past 2,500 years or so? There are plenty of candidates historically, but being Bayesians we should be cautious about overturning prior hypotheses on new data. Coalescence dating in particular is often an art as opposed to a science (I don’t mean this literally, but anyone who has used the programs mentioned in the paper knows what I mean).
An alternative model is that as a null we should expect star clusters now and then. But most people don’t seem to think that rapid expansion of Y chromosomes during the Holocene is simply a matter of chance as opposed to necessity.
* My boss and friend, Spencer Wells, was a coauthor on the paper.