Razib Khan One-stop-shopping for all of my content

June 28, 2011

“What if you’re wrong” – haplogroup J

Back when this sort of thing was cutting edge mtDNA haplogroup J was a pretty big deal. This was the haplogroup often associated with the demic diffusion of Middle Eastern farmers into Europe. This was the “Jasmine” clade in Seven Daughters of Eve. A new paper in PLoS ONE makes an audacious claim: that J is not a lineage which underwent recent demographic expansion, but rather one which has been subject to a specific set of evolutionary dynamics which have skewed the interpretations due to a false “molecular clock” assumption. By this assumption, I mean that mtDNA, which is passed down in an unbroken chain from mother to daughter, is by and large neutral to forces like natural selection and subject to a constant mutational rate which can serve as a calibration clock to the last common ancestor between two different lineages. Additionally, mtDNA has a high mutational rate, so it accumulates lots of variation to sample, and, it is copious, so easy to extract. What’s not to like?

First, the paper, Mutation Rate Switch inside Eurasian Mitochondrial Haplogroups: Impact of Selection and Consequences for Dating Settlement in Europe:

R-lineage mitochondrial DNA represents over 90% of the European ...

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