Y-chromosome study dates most recent common male ancestor to only 120 -156 thousand years ago

I am not quite sure why a difference in the time when our most recent common male ancestor (Y-chromosomal Adam) lived to that when our most recent common female ancestor (Mitochondrial Eve) lived should actually be a discrepancy which needs resolving.

Except of course if the authors wish to believe that all 7 billion humans alive today actually derive from a single couple!!

G. David Poznik et al, Sequencing Y Chromosomes Resolves Discrepancy in Time to Common Ancestor of Males Versus Females, Science 2 August 2013: 562-565. DOI:10.1126/science.1237619

This new study claims

… that this initial paper on Y chromosome sequence diversity provides important first evidence that the male most recent common ancestor did not live more recently than the female most recent common ancestor. 

The study involved Y chromosomes obtained through the Human Genome Diversity Project, and from other sources. It included chromosomes from 69 men in several populations in sub-Saharan Africa, and from Siberia, Cambodia, Pakistan, Algeria and Mexico.

Abstract: The Y chromosome and the mitochondrial genome have been used to estimate when the common patrilineal and matrilineal ancestors of humans lived. We sequenced the genomes of 69 males from nine populations, including two in which we find basal branches of the Y-chromosome tree. We identify ancient phylogenetic structure within African haplogroups and resolve a long-standing ambiguity deep within the tree. Applying equivalent methodologies to the Y chromosome and the mitochondrial genome, we estimate the time to the most recent common ancestor (TMRCA) of the Y chromosome to be 120 to 156 thousand years and the mitochondrial genome TMRCA to be 99 to 148 thousand years. Our findings suggest that, contrary to previous claims, male lineages do not coalesce significantly more recently than female lineages.

The study seems not to have looked at recent evidence of the age of the male lineage. This other evidence is more convincing and suggests that Y-chromosomal Adam is very much older and may lie some 237-581 thousand years ago and that Mitochondrial Eve goes back to about 200 thousand years ago.

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