Beginning 7,000 years ago, a bizarre thing has occurred in humans. Apparently, as new studies report, for the next 2,000 years, ancient humans’ genetic diversity has crumbled, especially the Y chromosomes diversity.
Both anthropologists and biologists were baffled by this fact. That, until recently when the scientists from the Stanford University think that they have come up with a straightforward but illuminating answer. Accordingly, the ancient humans’ genetic diversity collapse was the outcome of centuries of wars involving patrilineal clans.
Y-chromosome diversity collapse
This hypothesis came to a Stanford student, Tian Chen Zeng, who spent many hours studying online articles which theorized, poorly, as Zeng believed initially, on the roots of the so-called “Neolithic bottleneck of the Y-chromosome.”
However, it is quite common for humans genetic diversity to dive down occasionally but, on the other hand, the Y chromosome diversity collapse, resulting from the genetic patterns in contemporary humans, is quite bizarre. It was first seen only in males, more accurately, it was only discovered via the genes attached to the Y chromosome, that is transmitted by parents to offsprings.
Social changes in ancient humans society triggered the genetic diversity collapse
Besides, the researchers found that this ancient humans’ genetic diversity drop has occurred recently in comparison to other genetic changes that happened in ancient humans.
Accordingly, they believe that the so-called “Neolithic bottleneck of the Y-chromosome” has occurred as a result of the changes that happened in social structures and the crucial factor in this regard was how did the clans interact with each other.
Males in these clans were intertwined via their male forefathers and, thus, were more likely to carry identical Y-chromosomes. In terms of those chromosomes, anyway, it’s pretty much like everybody in those ancient clans had the same parent.
But that is only true inside each specific clan, while there could have been substantial genetic differences between different clans. To explain this, scientists said that wars killed whole clans eliminating Y-chromosome diversity in the process, which, eventually, lead to the observed ancient humans’ genetic diversity collapse.