Washington: First full-chromosome sequencing effort has found that most recent male and female common ancestors lived around the same time.
A study led by the Stanford University School of Medicine indicates the two roughly overlapped during evolutionary time - from between 120,000 to 156,000 years ago for the man, and between 99,000 and 148,000 years ago for the woman.
"Previous research has indicated that the male MRCA lived much more recently than the female MRCA," Carlos Bustamante, PhD, senior author and a professor of genetics at Stanford, said.
"But now our research shows that there`s no discrepancy," he said.
Previous estimates for the male MRCA ranged from between 50,000 to 115,000 years ago.
Despite the Adam and Eve monikers, which evoke a single couple whose children peopled the world, it is extremely unlikely that the male and female MRCAs were exact contemporaries.
And they weren`t the only man and woman alive at the time, or the only people to have present-day descendants.
These two individuals simply had the good fortune of successfully passing on specific portions of their DNA, called the Y chromosome and the mitochondrial genome, through the millennia to most of us, while the corresponding sequences of others have largely died out due to natural selection or a random process called genetic drift.
The DNA sequences traced by the researchers were chosen because of the unique way they are inherited: the Y chromosome is passed only from father to son, and the mitochondrial genome is passed from a mother to her children.
Each can serve as a useful tool for determining ancestral relationships because they don`t undergo the shuffling and swapping of genetic material that occurs routinely in most human chromosomes.
The researchers made their discovery by comparing Y-chromosome sequences among 69 men from nine globally distinct regions, including some that have only recently been available for study.
Regions represented included Namibia, the Democratic Republic of Congo, Gabon, Algeria, Pakistan, Cambodia, Siberia and Mexico.
The study is published in the journal Science.