We all carry our ancestry within us, imprinted in our DNA. We all know this in part because it provides the base for the increasingly popular ancestry DNA tests.
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What is perhaps less recognised is the way in which the science of genomics has totally transformed our knowledge of the deep human past.
Genomics, an interdisciplinary field of biology, focuses on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes.
Genomics allows us to map and compare DNA from even ancient specimens. It allows us to map changes over time, and to estimate when certain changes might have taken place. This has resulted in a knowledge explosion.
The mysterious Denisovans are a case in point.
Denisova Cave lies in the Altai Mountains in south-central Siberia near the border with Kazakhstan, China and Mongolia.
In 2010, a Russian team announced that the DNA analysis of a juvenile female finger bone from the site had revealed a new hominin species that they named the Denisovans after the cave. The Denisovans were cousins to the European based Neanderthals, but had separated from them several hundred thousand years before.
This was remarkable enough, but more was to follow. DNA analysis of other remains and of modern human populations suggested that the Denisovans were widely spread across Asia with two distinct lines, one in East Asia, a second in South East Asia.
Further, the results show that the Denisovans overlapped with the Neanderthals at Denisova and with both Homo Erectus and anatomically modern humans in East and South East Asia. The widespread nature of the Denisovan trace in dispersed anatomically modern human populations suggests extensive interbreeding with multiple Denisovan populations.
The DNA analysis also revealed that in their long journey out of Africa to the ancient continent called Sahul, the ancestors of the Papuans and Australian Aborigines had met and mated with the Denisovans.
This mating probably took place in what is now South East Asia close to Sahul.
However, the trace is so strong among Papuans that it raises the possibility that the Denisovans may have lived in Papua or nearby islands until as recently as 30,000 years ago.
This date is well within the period of Aboriginal occupation of Sahul. It raises an intriguing question: if the Denisovans were in Papua, then the northern extension of Sahul, did they penetrate further south into what is now the Australian continent?
Jim Belshaw's email is ndarala@optusnet.com . His New England life blog is
http://newenglandaustralia.blogspot.com/ : his New England history blog
http://newenglandhistory.blogspot.com.au/
