"What I think is exciting about this work is that it demonstrates what you can learn about deep human history by jointly reconstructing the full evolutionary history of a collection of sequences from both modern humans and archaic hominins," says computational biologist Adam Siepel, from the Cold Spring Harbor Laboratory in New York.
As we've seen in other recent studies, the team used a Bayesian algorithm to dig deep into patterns in the genomes – in this case in DNA from two ancient Neanderthals, one ancient Denisovan, and two modern-day African humans.
What the algorithm looked for was recombination events, where two sets of chromosomes are mixed together, which enabled the scientists to go back a long, long way in the history of the interbreeding of these species – as per the genetic markers left behind.
sapiens, emphasising the amount of interbreeding that was happening across the centuries, way before the major mass migration of modern human ancestors out of Africa some 50,000 years ago.