When Homo sapiens first migrated from Africa to the tropical islands of the Southwest Pacific, they encountered unfamiliar human species and new diseases..

But their immune systems may have picked up some survival tricks when they mated with the locals, the enigmatic Denisovans..

They gave them variants of immune genes that could protect the offspring of new arrivals from local diseases.. Some of these variants have survived in the genomes of people living in Papua New Guinea, according to a new study..

Researchers have known for a decade that the inhabitants of Papua New Guinea and other parts of Melanesia, a subregion of the Southwest Pacific Ocean, inherited up to 5% of their DNA from the Denisovans, an ancient people closely related to Neanderthals who arrived in Asia about 200,000 years ago..

Scientists suggest that such a gene swap benefited people in the past, possibly helping modern humans better resist local diseases..

But they are wondering how this DNA can influence how people look, behave and feel today.? Determining the functions of Neanderthal and Denisovan DNA in Melanesians is difficult because scientists have analyzed very little genetic data from living people in Papua New Guinea and other parts of Melanesia..

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A new study solves this problem by using the genetic data of 56 people from Papua New Guinea..

The researchers compared these genomes with those of Denisovans from Denisova Cave in Siberia, as well as Neanderthals.. They found that Papuans inherited from Denisovans an unusually high frequency of 82,000 genetic variants known as single nucleotide polymorphisms, which arise from differences in a single base or letter in the genetic code..

The team then looked up these variants in a database that links genes with different functions in different human tissues.. They found variants of genes associated with immunity, which, for example, can promote or increase the production of proteins by a nearby gene, or, conversely, turn off or weaken its function..

These changes can help optimize the immune system for specific pathogens in the environment – \u200b\u200btoo strong an immune response can be as deadly as the infection itself..

In Papuans, scientists have found many Denisovan variants that are located near genes known to influence the human immune response to viruses and other pathogens, such as influenza and chikungunya..

They then tested the function of eight Denisovan gene variants associated with the expression of proteins produced by two genes, specifically OAS2 and OAS3, "

Two of the Denisovan genetic variants found in these Papuan cell lines reduce transcription or the production of proteins that regulate cytokines, part of the immune system's defense against infections.. This low-key inflammatory response may have helped the Papuans resist the onslaught of new infections they might have faced in the region..

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Taken together, the study suggests that the Denisovan gene variants "

“In the tropics, where people are exposed to a lot of infectious diseases, you might want to lower the immune response a bit and not go too far,” he explains..

These findings echo earlier work on the role of Neanderthal variants in living Europeans.. DNA studies of Neanderthals and Denisovans in various populations show how mating with archaic humans long adapted to their regions provided a quick way for arriving modern Homo sapiens, which we all belong to, to gain useful genes, says computational biologist Janet Kelso..

The study shows that such gene sharing was an important mechanism for the rapid adaptation of people to new challenges, in particular to pathogens,"

However, in the future, he would like to test whether the Denisovan variants of the genes really give the Papuans a better chance to protect themselves from specific diseases or survive..

Overall, this study shows that "

Recall that in 2021, scientists from Austria, Great Britain and Germany studied bone fragments found in Denisova Cave and were able to identify five bones of hominids.. It turned out that three bones belonged to the Denisovans and are the oldest dated remains of representatives of this extinct species of people..

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Denisova Cave is located in the valley of the Anui River in Altai. The first archaeological work began here in 1978 and continues to this day.. The region gained worldwide popularity in 2010, when scientists published an article in the journal Nature, which described the discovery of an unknown species of ancient people.. She was different from both Neanderthals and Cro-Magnons. They were called Denisovans - according to the place of discovery.