Gaby
Researchers say genes we inherited from Neanderthals influence whether people wake up early and go to bed early — a trait that helps in places with short winter days.
This was reported by a team from the University of California, San Francisco. They found that, thanks to DNA passed down from prehistoric relatives, some of us wake up more easily and go to sleep earlier. Those people are often called larks.
“By analyzing fragments of Neanderthal DNA that remain in the genomes of modern humans, we discovered a striking trend,” said John Kapra, an epidemiologist and the study’s lead author. He found a clear influence of Neanderthal DNA on the genes that regulate modern humans’ biological clocks. Specifically, that influence increases the likelihood of being a lark.
How Scientists Made This Discovery
But first, a brief backstory. Waves of Homo sapiens migrated from Africa to Eurasia about 70,000 years ago. When they arrived, they encountered Neanderthals, who had already adapted to life in a colder climate after settling the area hundreds of thousands of years earlier. Through interbreeding, modern humans inherited roughly four percent of Neanderthal DNA, including genes related to skin pigmentation, hair, fat storage, and immunity.
Although most of the genes acquired through ancient interbreeding were filtered out over the course of evolution, a small fraction remains. Scientists think those remaining fragments helped early Homo sapiens adapt to new conditions in Eurasia.
Kapra and his colleagues analyzed DNA from modern humans and Neanderthals. The team found that different genetic variants help determine the circadian rhythms of the two groups, and they speculated that some modern people still carry those Neanderthal variants.
To test that idea, the researchers turned to the UK Biobank, which stores genetic, health, and lifestyle information on about half a million people. The scientists found a link between the presence of certain Neanderthal-derived genes in modern individuals and a tendency to wake up early.
At the same time, the researchers emphasize that you don’t need Neanderthal genes to be a lark. Hundreds of other genes influence sleep timing, and a range of ecological and cultural factors shape people’s routines. Overall, Neanderthal DNA likely explains only part of the picture, as reported by The Guardian.
Kapra says being a lark can be advantageous because it reflects a biological clock that adapts quickly to seasonal changes in daylight. “In higher latitudes, it’s advantageous to have a more flexible clock that can adjust to varying seasonal light levels,” he said.
The results were published in the journal Genome Biology and Evolution.
Mark Maslin, a professor at University College London who did not take part in the study, wryly noted, “Now we have genetic evidence that some of us are indeed larks.” He added, “The further north you go, the shorter the days in winter, when food is particularly scarce, so it’s important to start searching for food as soon as there’s light to work with.”
