Republication from phys.org

by Robyn Mills,

 

Proposed route of the ancestors of modern humans out of Africa and through Island Southeast Asia. Credit: University of Adelaide

Genetic analysis has revealed that the ancestors of modern humans interbred with at least five different archaic human groups as they moved out of Africa and across Eurasia.

While two of the archaic groups are currently known—the Neandertals and their sister group the Denisovans from Asia—the others remain unnamed and have only been detected as traces of DNA surviving in different modern populations. Island Southeast Asia appears to have been a particular hotbed of diversity.

Published in the Proceedings of the National Academy of Sciences (PNAS), researchers from the University of Adelaide’s Australian Centre for Ancient DNA (ACAD) have mapped the location of past “mixing events” (analysed from existing ) by contrasting the levels of archaic ancestry in the genomes of present-day populations around the world.

“Each of us carry within ourselves the genetic traces of these past mixing events,” says first author Dr. João Teixeira, Australian Research Council Research Associate, ACAD, at the University of Adelaide. “These archaic groups were widespread and genetically diverse, and they survive in each of us. Their story is an integral part of how we came to be.

“For example, all present-day populations show about 2% of Neandertal ancestry which means that Neandertal mixing with the ancestors of modern humans occurred soon after they left Africa, probably around 50,000 to 55,000 years ago somewhere in the Middle East.”

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