New research has thrown more light on theories of human ancestry and origin. It argues that Adam and Eve - the terms given to hypothetical common ancestor groups for the genetic lineages of modern men and women - may have a closer relationship than earlier believed.
It is important to note that Adam and Eve, in this context, do not refer to the original man and woman depicted in the Old Testament, but the common ancestors for the Y chromosome (which contains genetic material exchanged between father and son) and the mitochondrial DNA (which contains genetic material exchanged between mother and child).
A team of scientists from Stanford University, the University of Michigan Medical School and Stony Brook University claim to have "first evidence" that the most recent common ancestor (MRCA) of the male of our species may actually be older than the female.
"Our findings suggest that, contrary to previous claims, male lineages do not coalesce significantly more recently than female lineages," researchers noted in their report, published in the journal Science.
The findings were determined by sequencing the DNA of Y chromosomes from 69 men, drawn from different populations in sub-Saharan Africa, Siberia, Cambodia, Pakistan, Algeria and Mexico. The Y chromosome is passed only from father to son and does not exchange genetic material with other chromosomes.
DNA sequencing of Y chromosomes suggests man's MRCA lived sometime between 120,000 and 156,000 years ago. Earlier, a similar sequencing was carried out for women, revealing Eve (the hypothetical common group) existed between 99,000 and 148,000 years ago.
Essentially, what the research suggests is that the genetic lineage of modern man, which differs across populations, can be traced back to a hypothetically common mass of genetic material and that this material could actually be older than a similarly hypothetical common mass for modern women.
"Previous research has indicated that the male MRCA lived much more recently than the female MRCA. But now our research shows that there's no discrepancy. In fact, if anything, the Y chromosome may be a bit older," one of the researchers, Carlos D Bustamante, from Stanford's Department of Genetics, said in a statement.
"We're interested in understanding the historical relationships between many different human populations, and the migration patterns that have led to the peopling of the world," Jeffrey Kidd, who works with both Stanford and Michigan University's genetics department, said, adding the study would help other efforts to retracing male lineages.
For now, this study should help in settling the question of contemporaneous roots. While scientists accept that the Y chromosome and the mitochondrial DNA evolved separately, there was a degree of confusion so far over why there was so great a time difference between the two existing side-by-side.