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If you are an early riser, you probably inherited the Neanderthal gene

A new study suggests that Neanderthals were early risers and that some of today’s early morning risers may have inherited early riser genes from their Neanderthal ancestors.

According to the New York Timesthe new study compared the DNA of living humans with genetic material recovered from Neanderthal fossils and concluded that Neanderthals apparently had the same genetic variants as today’s early risers.

Neanderthal DNA studies since the 1990s have revealed the tangled history of our species. About 700,000 years ago, the paths of the ancestors of wise humans diverged, most likely in Africa. The ancestors of modern humans mostly stayed in Africa, but Neanderthals migrated into Eurasia.

About 400,000 years ago, human ancestors split into two parts. The early humans that spread westward became the Neanderthals, and their cousins ​​in the east formed the Denisovan hominids.

Two groups of humans lived on Earth for hundreds of thousands of years, hunting and gathering food, and finally disappeared from the fossil record about 40,000 years ago. At that time, early modern humans were scattered out of Africa, occasionally interbreeding with Neanderthals and Denisovans. Today, DNA fragments of these two groups are found in a large number of living humans.

The research done in the past few years by John Capra, a geneticist at the University of California and other scientists, showed that some of these inherited genes have a survival advantage. For example, the inherited immune genes of Neanderthals and Denisovans may have protected them against new pathogens they had not encountered in Africa.

Capra and his colleagues were curious to see if there was a connection between sleeping habits and shared genes between Neanderthals and Denisovans. For this reason, they in a new study in Journal of Genome Biology and Evolution has been published, investigated the possible effect of these genes on the daily habits of extinct humans.

Inside the cells of any animal, there are hundreds of proteins that react with each other during the day and night and fall and rise in a 24-hour cycle. These proteins control the time we sleep and wake up and also affect our appetite and metabolism.

To discover the circadian clock of Neanderthals and Denisovans, Capra’s group examined 246 genes controlling the body clock and compared the sample of genes found in extinct humans with the genes of modern humans.

The circadian clock of the Neanderthals changed to adapt to the new environment

The researchers found more than a thousand mutations that were exclusive to living humans, or Neanderthals and Denisovans. The analysis showed that many of these mutations likely have major effects on how the body clock works. For example, some body clock proteins that are abundant in our cells are much rarer in the cells of Neanderthals and Denisovans.

The researchers next looked at the small number of body clock variants inherited from some living Neanderthals and Denisovans. They scoured the British Medical Database (a database of the genomes of half a million British volunteers) to measure the effects of these variants on modern-day humans.

In addition to the DNA test, the test subjects answered a list of health-related questions, including sleep habits (being early risers or nocturnal). Surprisingly, almost all ancient variants of the body clock increased the volunteers’ likelihood of waking up early, says Capra. “Seeing this was really the most exciting moment of the study,” he says.

Geography may explain why early humans were early risers. Early humans lived in Africa, close to the equator where the duration of day and night is almost the same throughout the year. But Neanderthals and Denisovans moved to higher latitudes, days at higher latitudes are longer in summer and shorter in winter. Over hundreds of thousands of years, the circadian clock of these hominins may have adapted to their new environment.

After leaving Africa, early modern humans faced the challenges of adapting to higher latitudes. Some descendants of those humans, after interbreeding with Neanderthals and Denisovans, inherited body clock genes suitable for their new home.

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However, all conclusions are limited to one database. Capra plans to explore other databases of volunteers with different ancestries in the future. If the links hold, Capra hopes that studying ancient body clocks will lead to new ideas about how we adapt to a modern world whose circadian clock has been disrupted by night shifts and smartphones. Disruption of the circadian clock not only makes it difficult to get a good night’s sleep, but also increases the risk of cancer, obesity and many other disorders.

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