Notable: Inheritance of fitness in patrilineal societies

Notable paper: Heyer, E., Brandenburg, J.-T., Leonardi, M., Toupance, B., Balaresque, P., Hegay, T., Aldashev, A. and Austerlitz, F. (2015), Patrilineal populations show more male transmission of reproductive success than cognatic populations in Central Asia, which reduces their genetic diversity. American Journal of Physical Anthropology. doi:10.1002/ajpa.22739

Synopsis: Heyer and colleagues examined Y chromosome and mtDNA from several populations in Central Asia, including patrilineal populations (where inheritance is determined by the father’s line) and cognatic populations (where inheritance is determined by both parents’ lines). They found that gene genealogies indicate a substantial inheritance of reproductive success in most of the societies they examined, and in the patrilineal populations that inheritance of reproductive success especially determined a low variation of the Y chromosome relative to mtDNA and the autosomes.

Interesting because: Human populations are relatively inbred. One way that inbreeding can happen in a large population is if fitness is inherited: that is, most people tend to come from a few large families, and these tend to propagate through time. That’s exactly what Heyer and colleagues document in many of these Central Asian populations.

Sheds light upon… Recently, another study reported that Y chromosome diversity shows a bottleneck in early farmers. The press around that study concentrated upon a literal bottleneck, with a reduction in the number of males. In reality, an inheritance of reproductive success by males can explain the proliferation of a few patrilines in ancient people. That is, some measures of genetic variation can decrease even as population size is rapidly increasing, as long as some patrilines are increasing disproportionately.