All anatomically modern humans trace their origin to Africa.
People who naturally wake up early in the morning might have their Neanderthal ancestors to thank, suggests recent research published in the journal Genome Biology and Evolution. The study indicates a genetic connection, proposing that the ease of waking up early today could be attributed to the DNA inherited from Neanderthals tens of thousands of years ago.
According to the study, approximately 70,000 years ago, when early humans undertook the migration from Africa to Eurasia, a significant portion of them interbred with Neanderthals. The Neanderthals, having already adapted to the colder and darker climates of the northern regions, imparted certain genetic influences through this interbreeding. The lasting consequences of this genetic mingling are still observable today. People of non-African ancestry carry between 1 and 4 percent of Neanderthal DNA in their genetic makeup.
"By combining ancient DNA, large-scale genetic studies in modern humans, and artificial intelligence, we discovered substantial genetic differences in the circadian systems of Neanderthals and modern humans," said the paper's lead author, John Capra, an epidemiologist at the University of California in San Francisco.
"Then, by analyzing the bits of Neanderthal DNA that remain in modern human genomes, we discovered a striking trend: many of them have effects on the control of circadian genes in modern humans, and these effects are predominantly in the consistent direction of increasing the propensity to be a morning person. This change is consistent with the effects of living at higher latitudes on the circadian clocks of animals and likely enables more rapid alignment of the circadian clock with changing seasonal light patterns. Our next steps include applying these analyses to more diverse modern human populations, exploring the effects of the Neanderthal variants we identified on the circadian clock in model systems, and applying similar analyses to other potentially adaptive traits."