Rebecca Cann resumes the last Y and mt dates
The age of the most recent man or woman from whom all living humans today descended has been the subject of considerable debate. It has been suggested that the date of our last common maternal ancestor could have be three times older than that of our last common paternal ancestor. Two papers in this issue independently redate our most recent common paternal ancestor and find that there is rather little or no disparity with the age our common maternal ancestor. On page 565, Francalacci et al. (1) report their high resolution sampling of 1204 Sardinian men, yielding 11,763 phylogenetically informative and male-specific single-nucleotide Y-chromosome polymorphisms (MSY-SNPs), and generate a putative estimate of 180,000 to 200,000 years for the point at which all these and other human paternal lineages coalesce. In a separate study on page 562, Poznik et al. (2) detail their methods using sequences from 69 males drawn from nine populations, covering 9.99 million loci on the Y, and conclude that the most recent common paternal ancestor lived 120,000 to 156,000 years ago. These papers further confirm an earlier sequencing study (3) of 36 male donors that pushed the ancestral Y back to 115,000 years before present (yr B.P.), using almost 6800 variants shared by two or more men. This is roughly the same as the dates derived on the basis of mitochondrial genome analysis for the most recent common maternal ancestor (4). So now it seems that a population giving rise to the strictly maternal and strictly paternal portions of our genomes could have produced individuals who found each other in the same space and time.