Coalescent theory is a population genetics approach to reconstructing the history of populations. This paper by Trevor Cousins, Aylwyn Scally and Richard Durbin applies an advanced coalescent model to humans to infer our demographic history. We already knew that Neanderthals and non-African modern humans interbred 45,000 to 49,000 years ago, but the model covers even longer time periods, showing evidence for two separate human populations that diverged 1.5 million years ago came back together in an admixture event 300,000 years ago. All contemporary humans are descendants of this merged population.
Nehaveigur 