Thursday, 18 October 2012

Revising the human mutation rate: implications for understanding human evolution.

Scally, A., Durbin, R., 2012. Nat Rev Genet 13, 745-753. PERSPECTIVE.

Rather than using a phylogenetic approach to estimate the mutation rate to calibrate the ‘molecular clock’ (i.e. using a fossil of a known date to anchor the divergence time between two species) these authors advocate using de novo mutation rates between parent and offspring trios.  This halves the suggested mutation rate to 0.5x10-9 bp-1 year-1, although this depends on generation time.  Using this rate they re-calculate (i) the Neanderthal-AMH divergence to ~500kya, which is inline with mtDNA estimates, (ii) the split between Khoe-San and other modern humans to 250-300kya (which is older than the single locus estimates for the root of the human tree and requires re-evalaution of the models of dispersion across the globe), (iii) the split between the Yoruba and non-Africans to 90-130kya (meaning the Skhul-Qafzeh population might not be an earlier ‘failed dispersion’ population after all and potentially giving Middle Eastern Neanderthals and AMH a longer period of interbreeding) and (iv) European-Asia split re-dated to 40-80kya.  The revised mutation rate doubles the effective population size parameter, which again may affect previous models of AMH dispersals out of Africa. 


No comments:

Post a Comment