Using several genetic analytical methods, an international research team has identified an interbreeding event between the Neanderthals and modern humans that occurred about 100,000 years ago, which is tens of thousands of years earlier than that is currently known. Dr. FU Qiaomei, from Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, is part of this leading team of international scientists who has made this ground-breaking discovery to be published February 17th, 2016 in the Journal Nature.   

The authors have pieced together the first genetic evidence to support a scenario that some modern humans may have left Africa in an early migration and admixed with the archaic hominins in Eurasia before the ancestors of present-day non-Africans have migrated out of Africa, less than 65,000 years ago. The breakthrough involves one specific ‘Altai Neanderthal’ (Figure 1), whose remains were found in a cave in the Altai Mountains in southern Siberia. The individual shows signs of gene flow from modern humans, in comparison with the two Neanderthals from European caves that were also sequenced for this study as well as a Denisovan all appeared to lack the specific DNA that derived from modern humans. 

Some of their findings reveal that: 1) alleles in the windows of Altai Neanderthal genome with low divergence to Africans have higher divergence to the Denisovan than Denisovan windows with low divergence to Africans. The latter windows in the Altai Neanderthal genome have higher heterozygosity than in the Denisovan genome; 2) a demographic model that estimates a gene flow from these early modern humans into the ancestors of the Altai Neanderthal to be about 1.0–7.1%, and although the exact source is unclear, the authors suspect that it may have come from a deep population that has either split off from the ancestors of present-day Africans or from one of the early African lineages; and 3) complex computer simulations also support the data. 

The team was able to further calculate the time of early modern human introgression into the Altai Neanderthal lineage occurred 100,000–230,000 years ago, based on the amount of shared haplotypes (50 kilobases or longer in length) between the modern humans and Altai Neanderthal. This introgression is much older than the previously reported gene flow from the Neanderthals into modern humans outside Africa (47,000–65,000 years ago). Possibly, there was an extended lag between when this group branched off the modern human family tree, roughly 200,000 years ago, and when they left their genetic mark in the Altai Neanderthal, about 100,000 years ago, before losing themselves to extinction. 

This research was partly supported by the Special Foundation of President of the Chinese Academy of Sciences. 

Fig. 1 Dorsal view of the Denisova Neandertal toe bone. (Image by Bence Viola )

Contact:

FU Qiaomei

Email:fuqiaomei@ivpp.ac.cn

Institute of Vertebrate Paleontology and Paleoanthropology