A recent study indicates that the most common male ancestor of every single human being alive today may have lived 9,000 years earlier than what was previously thought. This ancestor, whom experts are referring to as "Adam" in reference to the first man created by God in biblical references, is said to have lived 209,000 years ago. Moreover, this new estimate means that "Adam" may have been alive in the same time period as "Eve," the most common female ancestor of modern humans.
A team of researchers from the University of Sheffield and the University of Houston conducted the study. Aside from providing what appears to be a more accurate timeline for the emergence of "Adam," the team also found new evidence the debunks the currently held theory that the Y chromosome came into existence before the advent of humans.
Dr. Eran Elhaik and Dr. Dan Graur, who hail from the University of Sheffield and the University of Houston respectively, published their findings in the European Journal of Human Genetics. The researchers were able to come out with two possible reasons for the emergence of the Y chromosome.
"This estimate raises two astonishing possibilities, either the novel Y chromosome was inherited after ancestral humans interbred with another species, or anatomically modern Homo sapiens emerged earlier than previously estimated and quickly became subdivided into genetically differentiated subpopulations," said the study.
The evidence also supports the theory that there may have been numerous Adams and Eves instead of just two distinct individuals. The new study clearly debunks an earlier study conducted by researchers from the Arizona Univeristy. The previous study states that the interbreeding of early humans with other similar species may have brought about the emergence of the Y chromosome in the modern human genome.
"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," Elhaik said.
Scientists have long been pondering on the issue of interbreeding in early humans and closely related species. The new study sheds light more light on the question but further research is required before a clear answer can be offered.