"It is obvious that modern humans did not interbreed with hominins living over 500,000 years ago. It is also clear that there was no single 'Adam' and 'Eve' but rather groups of 'Adams and 'Eves' living side by side and wandering together in our world," says Eran Elhaik. (Credit: Rob Brewer/Flickr)

Study raises doubts about prehuman Y chromosome

Researchers say they have new evidence that overturns a 2013 study describing the discovery of the Y chromosome that predates humanity.

The new research also suggests that our most common male ancestor walked the earth 209,000 years ago—9,000 years earlier than scientists commonly thought.

The study, conducted by Eran Elhaik from the University of Sheffield and Dan Graur from the University of Houston, is published in the European Journal of Human Genetics.

Elhaik and Graur used conventional biological models to date our most common male ancestor, known as “Adam.” Their findings put “Adam” within the time frame of his other half, “Eve,” the genetic maternal ancestor of humankind.

This contradicts an earlier study that claimed the human Y chromosome originated in a different species through interbreeding, which dates “Adam” to be twice as old.

“We can say with some certainty that modern humans emerged in Africa a little over 200,000 years ago,” says Elhaik.

“It is obvious that modern humans did not interbreed with hominins living over 500,000 years ago. It is also clear that there was no single ‘Adam’ and ‘Eve’ but rather groups of ‘Adams and ‘Eves’ living side by side and wandering together in our world.”

“The question to what extent did our humans forbearers interbreed with their closest relatives is one of the hottest questions in anthropology that remains open,” adds Elhaik.

Source: University of Sheffield