Olson had drawn on a paper by statistician Joseph Chang,5 which had explored for the first time how a two-parent model of population genetics would deal with common ancestry. Surprisingly, up until then (as in the research leading to “Mitochondrial Eve”) only single-sex inheritance had been used. Nevertheless despite his use of this unexceptionable paper many geneticists dismissed Olson’s recent date for a common ancestor as an absurdly low figure, thinking more in terms of the six-figure numbers