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
]
|