Thanks to grandmothers for "longevity genes"
Genes that created grandmothers have been found
Scientists have found the genetic basis of the phenomenon of grandparents – individuals who survive in human society even after the end of the age of fertility (when it is no longer possible to have children). Grandparents turned out to be so important for the survival of the human race that special gene variants appeared that protect people from diseases of the elderly, the authors of an article in the journal Proceedings of the National Academy of Sciences (Schwarz et al., Human-specific derived alleles of CD33 and other genes protect against postproductive cognitive decline) found out.
Doctor Ajit Varki and biologist Pascal Gagneux made their discovery by accident. They examined the CD33 gene, which is responsible for the inflammatory and immune response of the body to injuries and infections. In addition, this gene is associated with Alzheimer's disease: one of its variants contributes to the development of the disease, and the second, on the contrary, protects against it (blocking the formation of amyloid plaques).
Then the scientists compared how often both variants are present in the tissues of humans and chimpanzees (the closest modern relatives of Homo sapiens among primates). A destructive variant of CD33 was found in both humans and monkeys: that is, historically it appeared first. However, the protective variant occurs in humans four times more often. Thus, it was people who needed the gene responsible for preventing Alzheimer's disease – when elderly individuals appeared in their populations (chimpanzees usually die after losing the ability to conceive children).
Then Varki and Gagne decided to test their hypothesis on other gene variants – responsible for the late onset of Alzheimer's disease and for protection against high blood pressure, diabetes and cardiovascular diseases. These variants were checked against the database of the 1000 Genomes project. It turned out that many peoples of the Earth have these options, but they are absent from chimpanzees, bonobos and gorillas. In other words, the genes for protection against senile diseases took shape after the isolation of the genus Homo.
"Grandmothers are so important to us that we have even developed genes to protect their minds," Varkey noted (in a press release of Newly Evolved, Uniquely Human Gene Variants Protect Older Adults from Cognitive Decline – VM).
Anthropologist Kristen Hawkes put forward the "Grandmother hypothesis" back in the 1990s, drawing attention to the role of old women in the life of Tanzanian hunter-gatherers: they dug up roots and fed them to their grandchildren. According to Hawkes, females among human ancestors stopped dying at the age of 30-40 (like chimpanzees) thanks to grandmothers: they fed grandchildren, which helped their daughters to give birth to the next child sooner. As a result, the "longevity genes" in such families were passed on to an increasing number of individuals, and the average age of hominins over the past two million years has grown to 70 years.
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09.12.2015