Y, mtDNA, Adam, & Eve

For various reasons the idea of mitochondrial Eve and Y chromosomal Adam capture the public imagination. This frustrates many people, including me. I’ve gotten into the fatigue stage on this topic, but some sort of counter-attack is necessary against malignant memes. Even geneticists who don’t usually work with populations can get confused by the implications of mtDNA and Y chromosomal phylogenies. Melissa Wilson Sayres, who works on Y chromosomes, has a useful post (promised first of two) at Panda’s Thumb, Y and mtDNA are not Adam and Eve: Part 1. If you have friends/acquaintances who are confused by this issue, it might be a good place to start.

Much of the discussion around this topic was triggered by the recent paper in Science, Sequencing Y Chromosomes Resolves Discrepancy in Time to Common Ancestor of Males Versus Females. As Graham Coop observed on Twitter the idea of a “discrepancy” is not clear, insofar as it would not be that surprising if the last common ancestor of the extant Y chromosomal lineages existed at a different time than the last common ancestor of the mtDNA lineages. Expected coalescence is contingent upon various population genetic parameters such as effective population size, but expectations are also subject to variation in realized outcomes. And, as Sayres observes the references to the Adam & Eve analogy were present within the paper, fueling the fire. Finally, the reference to “dogma” tagged onto the end struck me as a touch too cute.

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Source: Discover Magazine – Gene Expression