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"When modern humans emigrated from Africa to the rest of the world roughly 100,000 years ago, they encountered Neanderthals in the Middle East who were living in small groups there and in parts of Europe. Modern humans and Neanderthals produced common descendants who then spread throughout Europe and Asia.
New findings in genetic research
This theory has been proven by genetic analyses: a comparison of the genome sequence of a Neanderthal with that of today’s humans outside Africa reveals that the latter carry roughly two percent of Neanderthal DNA in their genomes. This Neanderthal legacy affects for example an individual’s appearance and behaviour. Skin colour, hair colour and sleeping patterns are influenced, for example. This was the finding of our latest study, for which we drew on a British genetic database: besides genetic information, UK Biobank also contains data about the appearance, diseases and dietary habits of more than 100,000 registered men and women.
Why a small piece of Neanderthal lives on in us
Selective advantage could be the reason in some cases why many of us still carry a small proportion of Neanderthal DNA even today. Neanderthals were probably better adapted to the climatic conditions in Europe than modern humans – after all, they had been living there for several thousand years. The intensity of the sun plays a key role: ultraviolet radiation is far lower in Europe than in Africa, so having black skin is more of a hindrance when it comes to the vital production of vitamin D. That said, it is not possible to infer specific skin or hair colour from Neanderthal DNA. There is presumably an interplay of different genes that we are still unable to fully understand. What is more, the research findings do suggest that Neanderthals may also have had different skin and hair colours, though scientists have not discovered any evidence of red hair.
Genes influence our enjoyment of cigarettes
Our biorhythms and psychological characteristics, such as our predisposition to depression and lethargy, are likewise dependent on the sun’s radiation – and are influenced by Neanderthal DNA. Neanderthal variants are more commonly found in “night people”. Furthermore, this archaic genetic legacy increases our enjoyment of cigarettes. This is due to biochemical processes in the brain that are affected by the genes.
Better equipped to fight disease
Neanderthals may also have been more familiar with bacteria, viruses, parasites and nutritional resources, which is why certain Neanderthal variants were successfully passed on to our hereditary immune system. 40 to 50 percent of all humans living in Europe and Asia today still show Neanderthal sequences in those parts of their genetic make-up that are responsible for the immune system. This indicates that Neanderthal DNA continues to play a positive role in terms of defending us against infection.
Will Neanderthal DNA one day vanish entirely during the course of our future evolution? I do not believe so. Many of the different variants help us adapt better to our environment, making them extremely beneficial for modern humans."
Dr Janet Kelso
The five specialist departments of the Max Planck Institute of Evolutionary Anthropology bring together scientists from various fields who explore the history of humankind from different perspectives. Within the Department of Evolutionary Genetics, Janet Kelso runs the "Minerva Research Group for Bioinformatics". Together with her team, the bioinformatics expert unravels the DNA of Neanderthals and other extinct species of humans, and explores how modern humans continue to be influenced by this DNA.www.eva.mpg.de