The gene for early rising: humans inherited the tendency to wake up early from Neanderthals.

Researchers claim that genes inherited from Neanderthals influence modern humans’ tendency to wake up early and go to bed early. This trait is particularly beneficial in regions with short winter days.

This was stated by a team from the University of California, San Francisco. They found that thanks to the DNA passed down from prehistoric relatives, some of us wake up more easily and go to sleep earlier. Those individuals are often referred to as 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 lead author of the study. According to him, there is a clear influence of Neanderthal DNA on the genes of modern humans that regulate their biological clocks. Specifically, it “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. Upon arrival, they encountered Neanderthals, who had already adapted to life in a colder climate, having settled the area hundreds of thousands of years earlier. Through interbreeding between these two groups, modern humans inherited 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 have been filtered out over the course of evolution, a small fraction remains. Scientists believe this is likely because Neanderthals helped early Homo sapiens adapt to new living conditions in Eurasia.

John Kapra and his colleagues analyzed the DNA of modern humans and Neanderthals. The team noticed that different genetic variants are responsible for the circadian rhythms of these two groups. Since human ancestors mated with Neanderthals, it’s quite possible that some of our contemporaries carry Neanderthal variants, the researchers speculated.

To test this hypothesis, the researchers turned to the UK Biobank, which stores information about the genetics, health, and lifestyle of half a million people. Ultimately, the scientists found a connection between the presence of Neanderthal genes in modern individuals and their habit of waking up early.

At the same time, scientists believe that one doesn’t necessarily need to have genes from prehistoric relatives to be a lark. Hundreds of other genes also influence this habit. Moreover, a multitude of ecological and cultural factors contribute to the development of such a tendency. Thus, overall, Neanderthal genes account for only part of it, as reported by The Guardian.

In Mr. Kapra’s view, being a lark is actually beneficial. It indicates that we have a biological clock that quickly adapts to seasonal light changes. “In higher latitudes, it’s advantageous to have a more flexible clock that can adjust to varying seasonal light levels,” the researcher stated.

The results of the study were published in the journal Genome Biology and Evolution.

Professor Mark Maslin from University College London, who did not participate in the study, wryly noted, “Now we have genetic evidence that some of us are indeed larks.” Professor Maslin also 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 it as soon as there’s light to work with.”