As Y chromosomes are only passed from father to son, that would mean that the Y is a record of one’s patrilineage.
If the population growth rate is known, it is possible to test whether the observed frequency of a lineage is consistent with its level of variation, assuming neutrality…Using this method, we estimated the chance of finding the low degree of variation observed in the star cluster, with a current frequency of 8%, under neutral conditions.
Even with the demographic model most likely to lead to rapid increase of the lineage, double exponential growth, the probability was .
It’s characterized by a core haplotype, a nearby set of variants separated by one mutational step.
This suggests that the genetic variant has risen rapidly in frequency before mutations had time to build up variation and generate a more complex topology.
In 2003 a groundbreaking historical genetics paper reported results which indicated that a substantial proportion of men in the world are direct line descendants of Genghis Khan.
By direct line, I mean that they carry Y chromosomes which seem to have come down from an individual who lived approximately 1,000 years ago.
Not only were they non-Muslims, but the Mongol assault on West Asian Muslims societies was particularly deleterious; it is generally assumed that Iran and Mesopotamia’s relatively productive irrigation system were wrecked during the Mongol conquests to the point where it took centuries for them to rebound to their previous levels of productivity.
More symbolically, it was the Mongols who finally extinguished the Abbasid Caliphate.
From the perspective of moderns, who tend to conceive of historical patterns and forces in economic, or at least ideological, terms, this fixation on blood descent seems ridiculous.
I suspect that many pre-modern people, who were accustomed to small family groups and kin networks in a way we are not, would find our own surprise rather perplexing. First, they discovered that there was a particular Y chromosomal haplotype, a set of unique genetic markers, which was found across much of Asia.
This haplotype seems to have expanded relatively recently, as was evident from small number of mutational steps connecting all of the local variants.