The genome of a man who lived 45,0000 years ago has now be
reconstructed, from a fossil thighbone found in Siberia. Not only do the
results give insight into the expansion of modern humans from Africa into
Eurasia, but it is strong supportive evidence for the hypothesis that at one
point, modern humans interbred with Neanderthals. This was accomplished by a
team of scientists, led by geneticist Svante Pablo in Leipzig, Germany.
The team was able to do this by retrieving small parts of
genes, reading the sequences and joining the fragments together to make larger
pieces of the genome. They found that this man (who they deemed Ust’-Ishim man)
was part of a lineage that eventually gave rise to all non-African humans,
living after homo sapiens migrated from Africa, but before the species split
between Europe and Asia.
The team was also able to reconstruct a Neanderthal’s genome from a single toe bone. Comparing a Neanderthal’s genome to that of Ust’-Ishim
man, it was found that he had pieces of Neanderthal DNA in his genome, but with
the significant difference that he had much longer pieces of Neanderthal DNA,
compared to the much shorter fragments you would find in humans today. Thus showing
that he was part of a lineage more closely related to Neanderthals.
From the findings, the scientists hypothesize that humans
and Neanderthals interbred between 50,000 and 60,000 years ago, and that
non-Africans descended from a group of people this man belonged to, who moved
out of Africa, also around 60,000 years ago.
It’s very interesting to see the gaps in the history of our
species slowly be reconstructed. Although we may never know everything, this is
a great discovery. The hypothesis that we only just moved out of Africa, and
were interbreeding with another species, just 60,000 years ago is astonishing;
since that is not a long time ago in the great scheme of things, and much less
than the hypothesis 100,000 years ago. I hope that more discoveries like this
will not only reveal the past, but reveal how we slowly evolved into modern humans.
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