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An international team of researchers opened amazing genetic adaptation that allows people an incredibly long time to remain under water. And it’s not about the gills of the fish-man, and enlarged spleen.
Experts have studied people Bajo, of representatives who is also called "sea Gypsies". This ethnic group living in Malaysia, Indonesia and the Philippines, the number of which is about 700 thousand people.
More than a thousand years, the people of Bajo traveled to the South-East coast of Asia, living in floating homes without drinking water and electricity and eating seafood. Today, more and more "sea Gypsies" moved on land, but some members of the tribes still follow a nomadic way of life.
Scientists have long been interested in this unusual nation. In particular, they study the ability to hold breath for long periods of time and dive to a depth of 70-80 meters without any equipment (except for wooden glasses and fishing gear).
Earlier work has shown that the secret of such superpowers lies in the enlarged spleen. However, only experts now understand that this increase is responsible not that other, as changes at the genetic level.
According to the authors of the new work, from the point of view of physiology and genetics of the human spleen are not as well studied as we would like. However, study of this organ in the case of marine animals showed that in many mammals, the spleen has evolved to a disproportionately large (and some whales there are 14 spleen).
Experts have suggested that adaptive changes could happen with people previoustime for hundreds of years to "sea" way of life.
The fact that the size of the spleen depends directly on the so-called response to immersion under water – the mechanism to help them survive in an oxygen-free environment at low temperature (below body temperature).
When the person is immersed under water, slows the heart rate, blood vessels in the extremities constrict to maintain blood flow to vital organs. In addition, a person shrinks the spleen, which is accompanied by release of large amount of oxidized red blood cells in the bloodstream. The average oxygen level in blood increases by 9%, and this greatly extends the dive time, writes the website phys.org.
It is logical that the larger the spleen, the higher the level of provision of blood with life-giving oxygen, say the authors.
They lived a few months in the settlements of the people of Bajo, conducting various tests. Scientists were selected for analysis of genetic material, and conducted an ultrasound scan of the spleen as "sea Gypsies" (59 participants), and their neighbors from other tribes (34 participants), which gave preference to farming, not fishing.
The samples went to the University of Copenhagen (Denmark), where the team spent sequencing and comparative analyses. The results showed that people Bajo spleen were increased by approximately 50% compared to their "colleagues" farmers.
Interestingly, a relatively large proved and spleen are some of the other people that also spend a lot of time underwater when foraging.
Data sequencing was even more interesting: scientists have identified 25 genes that either differed or not at all present in people from other tribes.
In particular, "sea Gypsies" were found PDE10A gene that controls the level of thyroid hormone T4 (thyroxine).
"We believe that Baggio is adaptation, which increases the content of thyroid hormones and therefore increases the size of the spleen, says lead author Melissa Ilardo (Melissa Ilardo). — In mice, it was shown that thyroid hormones and the size of the spleen are connected. If you genetically modify mice to cancel the production of the hormone T4, the size of their spleen is dramatically reduced, but this effect is reversible with injections of the hormone T4".
In addition, the DNA of the people of the nation Bajo were found with other genes responsible for different reactions of the body to dive under the water. This, for example, genes that control changes in blood flow in different parts of the body and preventing the accumulation of carbon dioxide in the blood.
The team notes that this is the first case where genetic adaptation to a longer stay under water tracked in humans. And this is a clear demonstration that natural selection continues to work in human populations.
New data can be useful for future medical jobs. For example, many processes in the human body that are triggered when submerged under water, occur in hypoxia – oxygen starvation tissues and organs. In this sense, it would be interesting to compare the genome of the people with Baggio the genome of Tibetans and other peoples living at high altitude above sea level and having resistance to hypoxia, authors add.
The studies in this direction will lead to the development of new measures of emergency aid, methods of dealing with chronic hypoxia and treatment strategies of patients suffering from a temporary deficiency of oxygen, for example due to apnea during sleep or traumatic brain injury.
In addition, the researchers also want to study other populations of sea nomads and learn more about the unusual genetic adaptations. And we must act quickly, while these people have not lost their authenticity, since they are of great value not only for linguists and culture experts, but also for geneticists and science in General, conclude the experts.
Learn more about this wonderful work is told in article, published in the journal Cell.
By the way, the authors of the project "News.Science" (nauka.vesti.ru) reported another interesting study of the people of Samoa: "economical" gene saved the tribe from death, now obesity kills.
Also, scientists have revealed the secret "Ice man" from the Netherlands and revealed new features of the brain and body.