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Scientists have sequenced the oldest complete human genome.

The DNA comes from an anatomically modern man who roamed Western Siberia 45,000 years ago.

It provides experts with a more accurate timeline of when modern humans mated with their Neanderthal cousins as they moved from Africa into Europe, between 50,000 and 60,000 years ago. 

Scientists have sequenced the oldest complete human genome. The DNA comes from an anatomically modern man who roamed Western Siberia 45,000 years ago. His remains were fund near the settlement of Ust'-Ishim in western Siberia in 2008. A view of the river Irtysh and the village is pictured

The male lived around the time the populations of Europe and Asia divided.

His remains were found near the small village of Ust'-Ishim in western Siberia in 2008 when an ivory hunter looking for mammoth tusks stumbled across the bones on the banks of the River Irtysh.

They are believed to represent the oldest radiocarbon-dated modern human outside Africa and the Middle East, according to the study in Nature.

Dr Janet Kelso, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, retrieved DNA from the man's thighbone.

By studying the make-up of the man's DNA, scientists discovered that the male lived around the time the populations of Europe and Asia divided. A map of Pleistocene fossils showing nuclear DNA is pictured. The orange dots indicate Neanderthals, blue Denisovans and green, modern humans

Together with colleagues, she then sequenced and analysed the genome of the individual and found he had a similar level of Neanderthal ancestry as contemporary East Asians and Europeans.

Their study, led by Svante Pääbo, suggests that Neanderthal genes flowed into his ancestors 7,000 to 13,000 years before he lived.

Experts previously thought that interbreeding between anatomically modern humans and Neanderthals occurred anywhere between 37,000 and 86,000 years ago.

The new study narrows down this huge window of opportunity to between 50,000 and 60,000 years ago, which coincides with the expansion of modern humans into Europe, and possibly Asia.

This was decided by studying the segments of Neanderthal DNA in his genome, which were much longer than the ones found in present-day humans. 

More complex than a simple march of progress: The study suggests that interbreeding between anatomically modern humans (illustrated right) and Neanderthals occurred between 50,000 and 60,000 years ago, coinciding with the expansion of modern humans into Europe

'We present the high-quality genome sequence of a 45,000 year-old modern human male from Siberia,' Dr Kelso said.

'This individual derives from a population that lived before - or simultaneously with - the separation of the populations in western and eastern Eurasia and carries a similar amount of Neanderthal ancestry as present-day Eurasians.'

Chemical ratios in the bone indicated the man would have lived on berries, nuts, vegetables, meat and fish.

She added: 'Interestingly the Ust-Ushim individual probably lived during a warm period that has been proposed to be a time of expansion of modern humans into Europe.'