Timing of ancient human Y lineage depends on the mutation rate: A comment on Mendez et al

TL;DR

This paper critiques a recent study that reported an extremely ancient Y chromosome lineage, arguing that the estimated age is inconsistent with fossil and genetic evidence due to an underestimated mutation rate.

Contribution

It highlights the impact of mutation rate assumptions on Y chromosome TMRCA estimates and emphasizes the need for accurate mutation rates in human evolutionary studies.

Findings

Reported TMRCA (338 kya) is inconsistent with fossil and mtDNA data.

Low mutation rate used by Mendez et al. likely inflated TMRCA.

Accurate mutation rates are crucial for reliable human lineage dating.

Abstract

Mendez et al. recently report the identification of a Y chromosome lineage from an African American that is an outgroup to all other known Y haplotypes, and report a time to most recent common ancestor, TMRCA, for human Y lineages that is substantially longer than any previous estimate. The identification of a novel Y haplotype is always exciting, and this haplotype, in particular, is unique in its basal position on the Y haplotype tree. However, at 338 (237-581) thousand years ago, kya, the extremely ancient TMRCA reported by Mendez et al. is inconsistent with the known human fossil record (which estimate the age of anatomically modern humans at 195 +- 5 kya), with estimates from mtDNA (176.6 +- 11.3 kya, and 204.9 (116.8-295.7) kya) and with population genetic theory. The inflated TMRCA can quite easily be attributed to the extremely low Y chromosome mutation rate used by the authors.