Adam and Eve lived in Africa at the same time - but probably never met, scientists claim.
It
was previously believed that ‘Y-chromosomal Adam’ and ‘Mitochondrial
Eve’ - the most recent common ancestors to males and females - lived at
completely different times.
But
a new study of 69 men from around the world found ‘Y-chromosomal Adam’
walked the Earth between 120,000 and 156,000 years ago, much earlier
than previously believed.
A new study of 69 men from around the world
found 'Y-chromosomal Adam' walked the Earth between 120,000 and 156,000
years ago, much earlier than previously believed.
It places him nearer to Eve who was around 99,000 to 148,000 years ago
the analysis found
It places him nearer to Eve who was around 99,000 to 148,000 years ago the analysis found.
But the researchers say it is ‘extremely unlikely’ they were exact contemporaries.
Initial estimates for the male MRCA ranged from between 50,000 to 115,000 years ago.
Geneticist
Professor Carlos Bustamante, of Stanford University, California, said:
'Previous research has indicated the male most recent common ancestor
(MRCA) lived much more recently than the female MRCA. But now our
research shows there is no discrepancy.'
But despite the Adam and Eve
monikers, which evoke a single couple whose children peopled the world,
they were not the only man and woman alive at the time, or the only ones
to have present day descendants.
They
simply had the good fortune to successfully pass on the Y chromosome
and the mitochondrial genome across thousands of years to most of us.
Powerful,
state of the art microscopes allowed the identification of about 11,000
mutations, enabling the researchers to establish genetic links and
timelines with unprecedented accuracy.
The study obtained results for 10
million nucleotides, biological molecules that form the building blocks
of the Y chromosome, for each individual.
The annual mutation rate was then
estimated by comparing it with a known event, the human settlement of
the Americas about 15,000 years ago.
The tree, published in Science, also exemplifies
the extraordinary depth of genetic diversity present among modern
Africans. But it is also possible it represents a time when only a few
sequences were passed on and many died out due to an external event that
has not yet been identified
They repeated the analysis with
the individuals’ mitochondrial DNA to generate the two estimates for
Adam and Eve, showing for the first time they overlap.
Professor
Bustamante said: ‘We can now date certain events very precisely. We
found a single variant that shows how three ancient lineages came
together about 48,000 years ago, plus or minus only a couple of hundred
years. The accuracy is exquisite.’
The tree, published in Science, also exemplifies the extraordinary depth of genetic diversity present among modern Africans.
But
it is also possible it represents a time when only a few sequences were
passed on and many died out due to an external event that has not yet
been identified.
‘For
the most part, it is a random process. Some lineages die out, some are
successful,’ said David Poznik, a graduate student in Prof Bustamante’s
lab.
‘But
it is also possible there may be elements of human demographic history
that predispose these lineages to coalesce at certain times.’
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