Neanderthals were morning people and study suggests. And some modern people who like to get up early may be influenced by genes inherited from their Neanderthal ancestors.
A new study compared DNA from living humans with genetic material taken from Neanderthal fossils. It turns out that Neanderthals had some of the same clock-related genetic variations as people who are reported to be early risers.
Since the 1990s, studies of Neanderthal DNA have revealed the intertwined history of our species. About 700,000 years ago, our lineage diverged, probably in Africa. Most of the ancestors of modern humans remained in Africa, but Neanderthal lineages migrated to Eurasia.
About 400,000 years ago, the population split into two. Humans who spread westward became Neanderthals. Their cousins to the east evolved into a group known as the Denisovans.
These two groups lived by hunting and gathering plants for hundreds of thousands of years before disappearing from the fossil record about 40,000 years ago. By then, modern humans had expanded out of Africa, sometimes interbreeding with Neanderthals and Denisovans.
And today, fragments of their DNA are found in the bodies of most living humans.
Research conducted over the past few years by geneticist John Capra and other scientists at the University of California, San Francisco, suggests that some of these genes may carry over survival advantages. For example, immunity genes inherited from Neanderthals and Denisovans may have protected them from new pathogens never encountered in Africa.
Dr. Capra and his colleagues were intrigued to discover that some Neanderthal and Denisovan genes, which have become more common over the generations, are associated with sleep. A new study published in the journal Genome Biology and Evolution investigated how these genes influenced the daily rhythms of extinct humans.
Inside the cells of all kinds of animals, hundreds of proteins react with each other every day, increasing and decreasing in a 24-hour cycle. They not only control when we fall asleep and wake up, but also affect our appetite and metabolism.
To investigate circadian rhythms in Neanderthals and Denisovans, Dr. Capra and his colleagues looked at 246 genes that help control the body’s internal clock. They compared the genetic versions of extinct humans with those of modern humans.
Researchers have discovered more than 1,000 mutations unique only to modern humans or Neanderthals and Denisovans. Their analysis revealed that many of these mutations may have important effects on the operation of the body’s biological clock. For example, the researchers predicted that some of the internal clock proteins that are abundant in our cells would be much more scarce in Neanderthal and Denisovan cells.
The scientists then looked at a small number of biological clock mutations that some modern humans inherited from Neanderthals and Denisovans.To find out how these variants affect people, they UK Biobanka British database holding the genomes of 500,000 volunteers.
Along with their DNA, the volunteers provided answers to a long list of health questions. early riser or night owl. To Dr. Capra’s surprise, almost all ancient biological clock variants made the volunteers more likely to be morning people.
“Seeing that was the most exciting moment of this study,” Dr. Capra said.
Geography may explain why ancient hominins were early risers. Early humans lived in Africa, fairly close to the equator, where day and night hours were about the same throughout the year. However, Neanderthals and Denisovans moved to higher latitudes, where the days became longer in the summer and shorter in the winter. Over hundreds of thousands of years, their circadian clocks may have adapted to new environments.
When modern humans expanded out of Africa, they faced the same challenges of adapting to high latitudes. After they interbred with Neanderthals and Denisovans, some of their offspring inherited biological clock genes suited to their new homeland.
However, all these conclusions are based on a database limited to British people.Dr. Capra is starting to investigate. other databases of volunteers with other ancestry. If this connection holds, our ancient body clock could spark some ideas about how we can adapt to modern society, where our circadian rhythms are disrupted by night shifts and shiny smartphones. Dr. Capra hopes that this is the case. These disruptions don’t just make it difficult to get a good night’s sleep.they can also be cultivated cancer riskobesity and many other disorders.
Michael Dannemann, an evolutionary geneticist at the University of Tartu in Estonia who was not involved in the study, said one way to test Dr. Capra’s mutants would be to manipulate different human cells in the lab. He said it would make the genes more similar. Neanderthals and Denisovans. Scientists will then be able to grow clusters of cells and watch them go through daily cycles.
“This advance not only advances our knowledge of how Neanderthal DNA influences modern humans, but also provides an avenue to expand our understanding of Neanderthal biology itself.” he said.