Paabo said it was possible the Altai Neanderthals were 'such a small population that you've hardly any other choice' in sex partners, hence the interbreeding, though it matches findings of Neanderthanls from Europe. Picture: NY Times

Scientists say they have completed the first high-quality sequence of a Siberian Neanderthal female, whose bone fragment was found in the Denisova cave in Altai region. The international study - reported in Nature journal today - indicates a high level of inbreeding among our ancient relatives.

Yet it also shows breeding between different groups, namely the Denisovans, mated with Neanderthals, and humans plus a third, as yet dimly visible hominin living in Asia. 'We can see that the mama and papa of the individuals were very closely related - half siblings or so,' said research team leader Svante Paabo, of Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

The lack of diversity in the genetic material shows scientists that sex between closely related Siberia Neanderthals was regular generations before this female's time. Paabo said it was possible the Altai Neanderthals were 'such a small population that you've hardly any other choice' in sex partners, hence the interbreeding, though it matches findings of Neanderthanls from Europe.

Denisova cave, Altai mountains, Siberia. Pictures: Novosibirsk Institute of Archeology and Ethnography

'We present a high-quality genome sequence of a Neanderthal woman from Siberia. We show that her parents were related at the level of half-siblings and that mating among close relatives was common among her recent ancestors,' stated the study.

'We also sequenced the genome of a Neanderthal from the Caucasus to low coverage. An analysis of the relationships and population history of available archaic genomes and 25 present-day human genomes shows that several gene flow events occurred among Neanderthals, Denisovans and early modern humans, possibly including gene flow into Denisovans from an unknown archaic group, possibly 'home erectus'.

'Thus, interbreeding, albeit of low magnitude, occurred among many hominin groups in the Late Pleistocene. In addition, the high-quality Neanderthal genome allows us to establish a definitive list of substitutions that became fixed in modern humans after their separation from the ancestors of Neanderthals and Denisovans.'

'Neanderthals live on a little bit in people living outside Africa today,' said Paabo, representing 2 percent of the genome of all humans not originating from Africa.

Separate DNA analysis of the remains of a 50,000 year old girl's finger from the Altai cave earlier revealed the identity of a new type of human in 2010 - 'the Denisovans', closely related to the Neanderthals. Science Now reported that the findings could have a direct benefit for in understanding modern man's propensity to disease.

Separate DNA analysis of the remains of a 50,000 year old girl's finger from the Altai cave earlier revealed the identity of a new type of human in 2010 - 'the Denisovans', closely related to the Neanderthals. Picture: NY Times

Geneticist Tomas Lindahl of London Research Institute said: 'The most remarkable achievement has been to show that genetically meaningful and credible sequence data can be obtained from these fossil[s].'

This could lead to finding genes that modern humans have inherited from Neanderthals that either cause disease or protect us from it.

'There is also an interesting question of what, if anything, Neanderthal and Denisovan DNA may be doing in the people that have it today, and whether it has been of benefit or detriment to our species,' added Chris Stringer, a paleoanthropologist at the Natural History Museum in London, who was unconnected with the work.

The authors of 'The complete genome sequence of a Neanderthal from the Altai Mountains' include Kay Prufer, Fernando Racimo, Nick Patterson, Flora Jay, Sriram Sankararaman, Susanna Sawyer, Anja Heinze, Gabriel Renaud, Peter Sudmant, Cesare de Filippo, Heng Li, Swapan Mallick, Michael Dannemann, Qiaomei Fu, Martin Kircher, Martin Kuhlwilm, Michael Lachmann, Matthias Meyer, Matthias Ongyerth, Michael Siebauer, Christoph Theunert, Arti Tandon, Priya Moorjani, Joseph Pickrell, James Mullikin, Samuel Vohr, Richard Green, Ines Hellmann, Philip Johnson, Helene Blanche, Howard Cann, Jacob Kitzman, Jay Shendure, Evan Eichler, Ed Lein, Trygve Bakken, Liubov Golovanova, Vladimir Doronichev, Michael Shunkov, Anatoli Derevianko, Bence Viola, Montgomery Slatkin, David Reich, Janet Kelso and Svante Paabo.