Are YOU an early riser? You may have Neanderthal genes, study finds

Between 60 and 70 thousand years ago, the ancestors of modern humans were on the move, and their sexual behavior made their modern descendants more likely to be early risers, according to a new study.

Migrating to Europe, our ancient human ancestors left Africa and encountered Neanderthals and Denisovans, with whom we share 93 percent of our DNA.

New research suggests that the three groups interbred and passed on genes that helped subsequent generations adapt to the northern climate and sunlight.

Among them were genetic variants known to be associated with “morningness,” including those that have been specifically shown to regulate the circadian rhythm, our sleep-wake cycles.

So if you tend to get up early in the morning, this may be the reason.

To discover the impact of ancient genes today, a team of researchers from Vanderbilt University, the University of Pennsylvania and the University of California, San Francisco examined genetic data from a catalog of hundreds of thousands of people in the United Kingdom. .

Specifically, they performed a genome-wide association study (GWAS) to look for traits related to early waking.

A GWAS looks at genetic variants that are statistically related to people’s traits. In the past, GWAS have been responsible for identifying genes that increase people’s risk of developing diseases such as kidney disease or insomnia.

They compared these associations to genomes derived from three ancient hominids that the scientists had previously published: a 120,000-year-old Neanderthal and a 72,000-year-old Denisovan found in the mountains of Mongolia, and a 52,000-year-old Neanderthal from modern-day Croatia.

Woven into the fabric of the DNA of these ancient hominids were 16 variants associated with increased levels of “manneriness” in modern humans.

And among them were “clock genes” that specifically help regulate our circadian rhythm.

This DNA mix between modern human ancestors and hominids has long been suspected of passing on certain tendencies to their descendants.

Scientists suspect these adaptations may have helped them adapt to move to more northern latitudes.

Compared to Africa, Europe and Asia had larger seasonal differences in climate and sunlight.

And the genes identified in the new study may have shifted people toward a shorter circadian period, helping them survive the relatively shorter days.

Research suggests that a shorter circadian period helps people adapt more quickly to changing conditions.

“By analyzing the fragments of Neanderthal DNA that remain in modern human genomes, we discovered a surprising trend: many of them have effects on the control of circadian genes in modern humans and these effects are predominantly in a direction consistent with increasing propensity for be a morning day. person,” said lead author John Capra, an associate professor of epidemiology and biostatistics at the University of California, San Francisco, in a statement.

“This change is consistent with the effects of living at higher latitudes on animals’ circadian clocks and likely allows for more rapid alignment of the circadian clock with changing seasonal light patterns.”

The results appeared today in Genome biology and evolution.

Modern humans may have benefited from Neanderthal and Denisovan genetics, but unfortunately, this genetic Silk Road was not an equal exchange.

Neanderthals bore the brunt, previous research has indicated: interbreeding with modern humans may have led to a blood disorder that ultimately triggered their extinction.

Some important limitations accompany the new research.

First, humans carry many thousands of genes and behaviors are complex and involve much more than just one or two of them.

And although a GWAS can reveal genes related to early waking, something as complex as our morning behaviors is difficult to attribute to just a handful of genes.

Second, circadian rhythm genes don’t just refer to when people wake up.

While sleep-wake behaviors are an important part of the circadian rhythm, there are other processes in our body, such as digestion, that are dictated by the circadian rhythm.

Therefore, it is possible that genes that affect the circadian rhythm do not only affect morning behaviors.