Do you find it easy to wake up early? You may have Neanderthal ancestry

A study published this week in the journal Genome Biology and Evolution found that Neanderthal DNA is still present in some present-day humans and can determine whether someone is a naturally morning person.

Neanderthals are our closest extinct relatives, according to the Smithsonian National Museum of Natural History, and they had specific physical characteristics like larger noses, angular cheekbones, and stockier bodies. They were known to use sophisticated tools, control fire, were skilled at hunting, wore clothing, and lived in shelters.

Relationship with chronotype

“We found that Neanderthal DNA that remained in modern humans due to hybridization had a significant and directional effect on modern humans,” wrote study co-author Tony Capra, associate professor of epidemiology and biostatistics at the University of California, San Francisco. Email: francisco. “Specifically, Neanderthal DNA associated with chronotype consistently increases the tendency to be a morning person.”

This discovery could help people better understand their sleep habits today, as shift work, reliance on screens and other technology can affect our innate sleep habits.

Migration to high latitudes

When the ancestors of Eurasians – who today range from the British Isles to the mountains of Siberia – began migrating out of Africa about 70,000 years ago, they were exposed to new environments at higher latitudes with more diverse seasons, temperatures and levels of weather exposure. Light, according to the study.

Those who arrived in Eurasia interbred with current populations, “first with Neanderthals” and later with other ancestors, such as the Denisovans, who are now extinct, the study said. This created the possibility that humans would acquire genetic variants that were already adapted to these new environments.

“At high latitudes, there is greater seasonal variation in light/dark cycles throughout the year than at tropical latitudes,” Capra wrote.

It was not “immediately clear why increased early maturation would be beneficial at high latitudes,” although the study found that in modern humans, “earlier behavioral maturation” is associated with “a faster pacing of the biological gene network,” which may be an advantage. .

This discovery could help people better understand their sleep habits today, as shift work, reliance on screens and other technology can affect our innate sleep habits.

Changes in circadian rhythm

Our circadian rhythms are the body’s natural guide through the 24-hour cycle. They tell us when it is time to eat, sleep and wake up.

These are “intrinsic” rhythms that adapt the biology of animals and plants to Earth’s light-dark cycle, and are “regulated by a central circadian clock that is extracted from the environment” through light exposure, said Simon Archer, a professor of the molecular biology of sleep at Harvard University. University of Surrey in Britain.

Often, when people have trouble falling asleep or staying awake, it’s because their circadian rhythms are disrupted by health problems — including stress, depression, anxiety and hyperthyroidism — or by shift work or travel.

Changes like daylight saving time can also affect circadian rhythms, as the body loses an hour of sunlight in the morning, which experts say is key to maintaining a sleep-wake cycle and overall health.

Sleep problems can lead to changes in metabolism and immunity that are linked to health problems such as cancer, heart disease, and fatigue.

A number of new technologies, such as special masks, glasses, heart sensors and apps, have been developed to help solve these problems.

The study says that many of our Neanderthal genetic origins “were not beneficial and were removed by natural selection,” but some aspects are still present in human populations today and may “show evidence of adaptation.”

Daily differences from Neanderthals

In this study, researchers identified a set of 246 genes associated with the circadian clock, and found hundreds of genetic variants that have the potential to influence the circadian clock. Using artificial intelligence to analyze genetic differences, they found that it is possible that some humans may have acquired circadian clock differences from Neanderthals.

To test this, the researchers used a large group of hundreds of thousands of people, using a UK biomedical database. The study found that “these variables consistently increase prematurity,” according to a statement about the study.

Naomi Allen, professor of epidemiology at UK Biobank, said: “I’m sure no one could have predicted that we would actually see genetic evidence that some of us are already morning types.” The results came from “half a million volunteers sharing their de-identified genetic data and researchers from around the world asking them such interesting questions,” she said of the collaboration.

The study says that many Neanderthal genetic origins “were not beneficial and were removed by natural selection,” but some aspects are still present in human populations today and may “show evidence of adaptation.”

It can provide benefits

“The tendency to be a morning person would have been evolutionarily advantageous for our ancestors living at the high latitudes of Europe and would therefore be a Neanderthal genetic trait worth preserving,” the study says.

Capra wrote that the presence of Neanderthal DNA in certain parts of our genome could provide benefits, such as our immune system, metabolism, hair and skin.

“We don’t think being a morning person is actually beneficial, but this is actually an indication that you have a circadian clock that is better able to adapt to changing light levels,” he said. “Having a clock that runs faster also leads to waking up earlier.”

“At higher latitudes, it is useful to have a clock that is more flexible and can change better to match changing seasonal light levels,” he added.

“Hybridization between sapiens may in some cases have gained advantages, for example, allowing them to live in higher places [γεωγραφικά] Thomas Werg, clinical professor of medicine at the University of Copenhagen and director of the Institute of Biological Psychiatry at Copenhagen University Hospital, wrote in an email:

“Being a morning person is a very complex trait.”

Archer said the study is “very interesting” but “perhaps not surprising” because “biological clocks are an ancient evolutionary adaptation found in almost all organisms studied” and that “an adaptive advantage would make sense” if it was selected for and conserved by our ancestors.

DNA may also tell other stories, such as differences in why some people sleep or wake up later than others, Archer said. “For primates and our ancestors, this may have provided a selective advantage, as not everyone sleeps at the same time,” Archer said. time”.

But, Archer said, in modern society, “if you’re a nocturnal person, there are potential risk factors associated with that,” such as sleep deprivation, poor health, exposure to too much artificial light and poor nutrition.

But the presence of traces of Neanderthal DNA is only one element that can determine your sleep habits.

Capra explained that “being a morning person is a very complex trait” and that hundreds of different genes as well as environmental and cultural factors “strongly influence” it.

“There are a lot of early humans who didn’t have any of these primitive variants,” he concluded.

*With data from washingtonpost.com