Ancient Africans in search of mates traded long-distance travels for regional connections starting about 20,000 years ago, an analysis of ancient and modern DNA suggests. That shift occurred after treks across much of Africa to find breeding partners had been the norm starting at least 50,000 years ago, the same analysis shows.
These new findings, helped by several examples of the oldest human DNA from Africa isolated to date, offer the first genetic support for a previously suspected change in mating patterns around that time. These newly identified, long-distance movements of ancient human groups help explain archaeological discoveries of common types of stone and bone toolmaking and other cultural behaviors that increasingly appeared across much of Africa beginning about 50,000 years ago, evolutionary geneticist Mark Lipson of Harvard Medical School and colleagues report February 23 in Nature.
Comparisons of ancient human DNA to that of present-day hunter-gatherers and herders in the same three parts of Africa indicate that people generally stopped traveling outside their home regions to find mating partners about 20,000 years ago, the team says. People may have stayed closer to home at least partly because the last ice age peaked around that time, reducing the number of areas harboring enough edible plants, animals, and other resources needed to survive, says Yale University bioarchaeologist and study coauthor Jessica Thompson.