Before the mutation that allowed them to turn medium chains of omega-6 from plant sources into substances necessary for the brain, they were close to the water sources in central Africa and depended on a diet of fish and oysters
A genetic mutation appeared thousands of years ago, may answer the question of how humans managed to move from central Africa along and across the continent in what is now known as "The Great Expansion". This is according to a study carried out in several institutions in the USA.
By analyzing the genetic variation in sequences from different populations around the world, three teams of scientists from Wake Forest Baptist Medical Center, and the schools of medicine at Johns Hopkins University and the University of Washington in Seattle were able to show that the critical genetic variation emerged in a cluster of important genes on chromosome 11, known as the fatty acid desaturase or FADS for short, over 85 thousand years ago.
This variation allowed early humans to convert polyunsaturated fatty acid from plant sources (PUFA) into PUFA fats essential for increasing brain size, complexity and function. The FADS cluster plays an important role in determining how efficiently the short chain PUFAs found in plants are converted to the long chains found in the brain. The study was published in the journal PLOS ONE.
Archaeological and genetic studies suggest that Homo sapiens appeared about 180 thousand years ago, but remained in one area near the water bodies of central Africa for almost a hundred thousand years.
The paper's senior researcher, Floyd Ski Chilton, professor of physiology and pharmacology and director of the Center for Plant Lipids and Inflammatory Disease Prevention at Wake Force, and others speculated that the location was critical, in part because early humans needed large amounts of long-chain PUFAs found in fish and shellfish to support in complex brain functions.
"This may be why the first humans stuck to the water bodies in central Africa where they had a food source that provided them with DHA. Chilton said.
"There has been debate as to how early humans were able to obtain enough DHA to maintain their brain size and complexity. It's amazing to think that we discovered the area of genetic variation that appeared around the same time that the first humans moved out of central Africa, a process known as the "Great Expansion."
After the trait appeared, the study showed that it was subject to strong selective pressure and therefore spread rapidly in the Homo sapiens population throughout the African continent.
"The power of genetics continues to impress me and I found it impressive that we were able to locate things that happened tens of thousands of years ago through the study of the genetic variation found in the population today" says Joshua Akey, the lead scientist from the University of Washington.
This conversion means that early humans did not have to rely on one food source - fish - for brain growth and development. This was especially important because the genetic variation appeared before organized hunting and fishing could provide more reliable sources of long-chain PUFAs, Akey says.
To investigate the evolutionary forces shaping the different patterns in the FADS gene cluster in geographically distributed populations, the researchers analyzed 1,092 individuals representing 15 different human populations, which were sequenced as part of the Thousand Genomes Project, as well as 1,043 individuals from 52 populations from the Human Genome Diversity Panel database. They focused on the FADS cluster because they knew they knew the genetic code for enzymatic steps in long-chain PUFAs that are synthesized in a less efficient way.
The collaboration included three researchers from different disciplines - fatty acid biochemistry (Wake), statistical genetics (Johns Hopkins) and population genetics (University of Washington). This information is also based on the findings of a 2011 study by Chilton published in BMC Genetics that showed how people of African descent had a higher frequency of genetic variation that converts medium-chain omega-6 fatty acids found in cooking oil and processed foods into PUFA chains the long ones that cause inflammation.
Compared to whites, African-Americans in the US had higher rates of high blood pressure, type 2 diabetes, stroke, coronary heart disease and certain types of cancer. "The current observation provides another important clue to the question of why racially and ethnically diverse populations respond in different ways to the modern Western diet." Chilton says.
to the notice of the researchers
Upon his departure from Africa, primitive man stuck to the coasts
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It is not clear what happened to those humans who did not eat fish and oysters - did they perish? Or were they mentally inferior to those who did eat fish?
If so, what is the difficulty in sending expeditions to search for fish?
It doesn't sound likely that one fatty acid (omega 6) is responsible for brain development.
It is more likely that the change in diet resulted in the development of the ability to use vegetable fat, instead of that of fish.
The claim that the FADS gene cluster appeared 85 thousand years ago is not substantiated in the article written here. In general, it is impossible to determine the state of the genes according to the fossils (because in the process of fossilization nothing remains of the genes). On the other hand - it is impossible to date the appearance of FADS by comparing genes from contemporary ethnic groups (after all, according to the article, this cluster became exclusive shortly after its appearance).
Mentioning the health status of African Americans today seems irrelevant at all to the story of FADS. Adaptation to new food takes hundreds of years, not to mention different eating and living habits in different ethnic groups; All of which are more influential than an event that took place 85 thousand years ago and ended with the protection of the entire population shortly thereafter.
"Compared to whites, African-Americans in the US had higher rates of high blood pressure, type 2 diabetes, stroke, coronary heart disease and certain types of cancer." It is possible that the reason for all these troubles that fall in higher rates on African Americans in the US than on whites there, is that since they are on average in the lower deciles of the population, the scope of eating junk food by them is higher, because it is cheaper food and therefore they are diabetic and have higher blood pressure and therefore suffer more strokes and heart disease.
Thanks. I will fix it
My father, several times in the article it is written that the fatty acids are converted into proteins. This is a mistake, the fatty acids are converted into longer fatty acids.
The article is really not clear and is written in a clumsy and difficult way for someone who is not familiar with biology or biochemistry to understand.
It can be briefly summarized that a mutation in the genome led to the creation of an enzyme/water necessary to extend short unsaturated fatty acids into longer ones, thus actually solving the human need to get docosahexaenoic acid (DHA) from food. The DHA acid is critical for the development of the brain and the nervous system in general (this acid occupies about 40% of the total unsaturated fatty acids in the brain and about 60% of the total unsaturated fatty acids in the visual system). By acquiring a genetic mutation that is mentioned in the article, an enzyme is created (in my estimation delta-4 destorase) that converts the unsaturated fatty acid - eicosapentaenoic acid (EPA) into a longer acid called DHA.
The article is not so clear. I'm not a biologist and I couldn't understand what exactly they tested. Did the researchers have genetic samples of Homo sapiens from the period? Besides, I realized that exactly at the time when it is assumed that Homo sapiens began to spread outside of its natural habitat, a genetic variation appeared that allowed it to carry out the migration.
The Neanderthals and other populations of hominids also spread in other parts of the world and there is evidence of the use of diverse food sources, to say that only modern humans have the gene that allows the use of certain types of food sounds absurd to me.
I did not understand anything