Sunday, November 27, 2016

Our parsimonious ancestry

From a previous post:
Paternal haplogroups are families of Y chromosomes that all trace back to a single mutation at a specific place and time.
Similarly, mitochondrial haplogroups trace back to a single mutation at a specific place and time.

Wiki lists 20 major Y-haplogroups. There seem to be a similar number of major mitochondrial haplogroups (e.g., see here.) Since the origin of the haplogroup ultimately traces to one individual, we are all, 7+ billion, ultimately descended from about 20 men and 20 women.

Oh, we are descended from a lot more than the 20 men and women I previously mentioned. For example, all non-Africans have a 1-2% Neanderthal admixture; but there are no Neanderthal paternal or mitochondrial haplogroups among today's humans as far as I know. What we mean is that only about 20 men (and 20 women) who lived long ago have unbroken patrilineal (and matrilineal) lines of descent.