2023-12-14 11:09:21
– Why some of us are morning grouches – and others are not
People who go to bed early and wake up early may owe this habit to the Neanderthals with whom their ancestors reproduced, scientists say.
Published today at 12:09 p.m
Was he a good morning person? A reconstruction of the face of the oldest Neanderthal found in the Netherlands, nicknamed Krijn.
Photo: Bart Maat (Getty Images/AFP)
Researchers have found that the DNA we inherited from Neanderthals – a cousin in our family tree – may have made some people more likely to be early risers and find it easier to go to bed earlier than others.
While most of the genes that modern humans gained through cross-breeding in ancient times have been eradicated by evolution, a small proportion have remained. “When we analyzed the portions of Neanderthal DNA that remained in the modern human genome, we discovered a striking trend,” said John Capra, an epidemiologist at the University of California, San Francisco. Many of them involved genes that control the body’s internal clock (also called “circadian rhythm”) in modern humans, and in most cases led to an “increase in the propensity to be a morning person,” said Capra.
To test this, Capra and his team turned to a large British biobank that has data from half a million people. Not only did many people carry the variants, the genes were also consistently linked to “early waking,” the scientists write in the journal “Genome Biology and Evolution.”
Capra suspects that many modern humans carry Neanderthal genes because they helped their ancestors adapt to life at higher latitudes. “We don’t think being a morning person was actually beneficial. Rather, we believe that it is a signal for a faster-running internal clock that can better adapt to seasonal fluctuations in light conditions,” says Capra.
Professor Mark Maslin from University College London, who was not involved in the study, provided an explanation for this to the Guardian. “Now we have genetic evidence that some of us really are morning people. When humans evolved in tropical Africa, day length averaged 12 hours. Today, hunter-gatherers spend only 30 percent of their waking hours gathering food, so 12 hours is a lot of time. But the further north you go, the shorter the days become in winter, when food is particularly scarce. That’s why it makes sense for Neanderthals and humans to start collecting food as soon as there is light to work with.”
You don’t need Neanderthal genes to be a morning person
Around 70,000 years ago, waves of Homo sapiens migrated from Africa to Eurasia. When they arrived, they encountered the Neanderthals, who had already adapted to the colder climate following inhabiting the area hundreds of thousands of years earlier. Thanks to interbreeding between the two groups, people alive today carry up to 4 percent of Neanderthal DNA, including genes related to skin pigmentation, hair, fat and immunity.
Overall, Neanderthal genes have only a small influence on when people sleep and wake up. Hundreds of different genes are responsible for this, but also many cultural and environmental influences.
Related articlesUrs Nagel has been an online site manager and news journalist at Tamedia since 2018.More information
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