Newly discovered hominid triggers rethink of human prehistory
A hominid that lived in southern Siberia some 40,000 years ago could be a new branch of the human family tree. This scientific finding has triggered a rethink of our prehistory.
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Scientists reported in Nature journal on Wednesday that they have discovered a “new creature” by sequencing DNA from the bone fragment of a little finger found in a cave in the Alta mountains. The bone, possibly from a small child, was extricated in 2008 from a soil layer carbon-dated to be between 30,000 to 48,000 years ago.
The study, led by Johannes Krause of Germany’s Max Planck Institute for Evolutionary Anthropology, found that the Siberian hominid had some 400 genetic differences. This means it is possible that it is an entirely distinct species of Homo, as the genus for humans and closely related primates is known.
If their findings are confirmed, much of the early tale of human settlement will have to be revamped. A common narrative is that Homo arose in east Africa. The first hominid to venture beyond this cradle was Homo erectus, around 1.9 million years ago.
If a "molecular clock" calculation of DNA change is right, the study suggests the Denisova hominid lineage came from Africa. Yet its ancestor was not Homo erectus but a member of a previously unknown out-of-Africa movement.
Until recently, it was thought the only human species inhabiting the planet around 40,000 years ago were us and the Neanderthals. The two-species picture dramatically changed in 2003, when "hobbit hominids", metre-high humans with brains the size of a grapefruit, showed up in fossilised form on the Indonesian island of Flores.
If the "hobbits" and the Denisova human are accepted as a separate species, that brings to four the tally of hominids who were all living at the same time and, in some cases, quite close to each other.
The question scientists are now asking themselves is, if this is the case, what happened? Did Homo sapiens, bigger brained and smarter in communication, wipe out the other species? Were the other species wiped out by some natural phenomenon or food crisis to which they could not adapt? Or was there interbreeding, meaning that the extinct species are, in a DNA sense, living today through some genes in all of us?
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