Early risers may have inherited their genes from Neanderthals
Homo sapiens once interbred with
Archaic Introgression Shaped Human Circadian Traits | Genome Biology and Evolution | Oxford Academic
https://academic.oup.com/gbe/article/15/12/evad203/7457904
Are You an Early Riser? You Might Carry Genes from These Ancient Humans
https://www.inverse.com/health/are-you-early-riser-ancient-humans-neanderthal-genes
Early risers may have inherited faster body clock from Neanderthals | CNN
https://edition.cnn.com/2023/12/14/health/early-risers-neanderthal-dna-scn/index.html
Neanderthals are believed to have gone extinct 20,000 to 40,000 years ago, but it is known that they interbred with modern humans, Homo sapiens, before that, and that some of their DNA has been passed down to modern humans. A 2023 study found that subjects in Peru, where many people have Native American ancestry, had a high rate of mutations in the DNA called ' SCN9A ,' which codes for the sodium channel Nav1.7, which sends sodium into cells and helps transmit pain nerve signals. The SCN9A DNA mutation is thought to have been inherited from Neanderthals, and as a result, it was concluded that 'subjects with DNA mutations derived from Neanderthals feel pain with less force than subjects without them.'
Research results show that 'Neanderthal DNA' influences modern humans' pain sensitivity - GIGAZINE
Tony Capra, a professor of pharmacology and biostatistics at the University of California, San Francisco, believes that the same thing may be related to the circadian rhythms of modern humans. As Neanderthals evolved at high latitudes in Europe and Asia, they may have had internal clocks that were easily adapted to areas with large seasonal changes in sunlight. It was estimated that modern humans who inherited Neanderthal DNA were more likely to adapt to the sun and become 'morning types.'
The study compared DNA from the standard human genome, Neanderthal DNA ranging from 52,000 to 122,000 years ago, and the DNA of Denisovans , an ancient human species closely related to Neanderthals, and looked at the UK Biobank to see if humans living today carry Neanderthal genetic variants and how they affect circadian rhythms.
As a result, the research team concluded, 'We found that Neanderthal DNA remaining in modern humans through interbreeding has a variety of effects on modern humans. In particular, Neanderthal DNA associated with circadian rhythms consistently increases the tendency to be morning people.'
People who live at high latitudes tend to be morning types, but it's unclear why being a morning type is advantageous in high latitudes where daylight hours are more variable. 'This isn't actually an evolutionary advantage, but rather it has to do with having a 'working clock' that can adapt well to seasonal changes in light,' Capra explains. 'What's important is how quickly we can entrain our internal clock to new patterns and avoid the negative effects of a mismatch between our internal clock and daylight hours.'
In addition, the study analyzed three types of Neanderthal DNA, and found that even the same Neanderthal had different DNA related to circadian rhythms. 'Understanding circadian DNA may tell us whether the Neanderthal lived at a high latitude where daylight hours were more variable, or at a low latitude where they had less need to adapt to changes in daylight,' Capra argued.
According to Capra, this study has some limitations, such as only being able to analyze a total of four ancient human DNAs and not accurately taking into account environmental factors other than seasonal variations that should have existed in ancient times. However, it is highly likely that DNA mutations played an important role in modern humans' environmental adaptation, so the next step is to directly test and confirm the effect of Neanderthal DNA on circadian rhythms in cells using genetic engineering.
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in Science, Posted by log1e_dh