We are not alone. An unknown group of archaic humans interbred with our more modern species in Africa thousands of years ago, contributing DNA that is still with us, according to a new scientific paper. These ghosts within our genome are revising the history of Homo sapiens, which once was thought to have crushed any humanlike competitors on its way to inheriting the earth. In reality, we had sex and had kids with these extinct groups.
In fact, this is the third population of archaic humans—groups slightly different from the modern mold—that we consorted with. Within the last two years, scientists have pulled ancient DNA from Neanderthal bones and learned that it matches some of ours. And a finger bone from a cave in Siberia, belonging to a 30,000-year-old group called the Denisovans, has yielded a different set of DNA that we carry as well. Now comes evidence of these unknown Africans. But this time the hints of an ancient dalliance don’t stem from fossils but from DNA alone.
Hadza archers in Tanzania
They are small stretches of genetic material that turned up in three hunter-gatherer groups: Pygmies in western Cameroon, and the Hadza and the Sandawe in Tanzania. The material doesn’t look as if it originated with those groups, but because it is common to all three, it seems to have been introduced prior to 40,000 years ago, when the groups split apart. (If the DNA entered three populations after the split, it would be unlikely to be so similar in all three of them.)
