The Genetic Ancestors of the Human Race May Have Lived in the Same Time Period

by Kareem Massie, age 16

The genetic samples of the human race's most recent common ancestors are biblically nicknamed. For years, scientists thought "Y chromosome Adam" and "Mitochondrial Eve" never lived in the same time or place. Now, recent evidence suggests these ancient ancestors may have in fact resided close to each other in the same era.

Since the 1980’s, scientists believed that Eve lived hundreds of thousands of years before Adam. By charting the mitochondrial DNA, which is passed on only from mother to child, scientists concluded that Mitochondrial Eve lived about 200,000 years ago in Africa. Similar studies that analyzed Adam’s Y chromosome, which is shared by all currently living males, revealed that Y chromosome Adam lived about 100,000 years ago.

Two teams of scientists recently published studies in the Journal Science that question these findings. By sequencing the Y chromosomes of living men in various parts of the world, scientists uncovered thousands of previously unknown variations of the chromosome. This allowed scientists to establish a more reliable timeframe for when Y chromosome Adam lived.

These new studies suggested that Y chromosome Adam lived between 120,000 to 200,000 years ago. Similar analysis of men’s mitochondrial DNA revealed that Mitochondrial Eve lived between 99,000 and 148,000 years ago.

Carlos D. Bustamante, a geneticist at the Stanford University School of Medicine, points out that Y chromosome Adam and Mitochondrial Eve most likely never met. Not all genetic material descended from these two ancestors; their DNA sequence comprise a piece of the human genome. The rest of the genome comes from thousands of other ancestors.

For years scientists, based on old studies, believed that these two ancient ancestors lived during different eras. Scientists say these new studies are a more reliable source of information. They now believe that “Y chromosome Adam” and “Mitochondrial Eve” may have coexisted in the same lifetime.

[Source: The New York Times]