Scientists have discovered that aging begins even before the baby is born - in the womb. By this phenomenon, they explain the high mortality at the beginning of life.
Thanks to their research, scientists were able to understand where the failure in the region of 9 years comes from on the human mortality curve, writes Cell Reports .
One of the main criteria for aging is mortality - if the risk of mortality in the body increases over time, then it is aging. According to the Gompertz curve , the risk of human mortality begins to grow rapidly from a specific age. But there was a gap before this place - scientists could not understand what was happening up to this point.
For example, the risk of mortality from the beginning of life gradually decreases, reaching a minimum in the region of 9 years, and then begins to grow again. If we apply the widespread aging criterion to this period, it turns out that a person is younger than 9 years old, and begins to age with time, and at the age of 20 this process only accelerates.
Scientists at Harvard Medical School have collected mortality data for people of different ages to figure out where the gap comes from. First, experts built a graph of mortality from all possible causes in 19 countries from 1999 to 2015, and a failure in the region of 9 years was observed everywhere. After ugly research with other data and statistics, the result was exactly the same.
Then scientists suggested that since age-related diseases determine the risk of death for young people and even children, aging can begin earlier.
To test their hypothesis, scientists measured old age at the intracellular level. They turned to the database of mutations in tumor cells and calculated how many mutations can be found in tumors in people of different ages. However, the number of mutations was not very consistent with biological age, because over time they accumulate in all cells of the body, and the number of mutations has been growing from the very beginning of life.
After that, scientists decided to build a curve for another marker of biological age - the degree of DNA methylation . Scientists based on epigenetic watches, which were created only in 2013.
But even in this case, the growth graph was not similar to the Gompertz curve, because the degree of methylation increased over the years in the first years of life, and then smoothed out.
After the observations, scientists made two significant conclusions. First , the body ages from the first weeks of fetal development, because at this time the first markers of biological age appear. The second - in this case, the common criterion of aging does not work, because in young children the mortality rate decreases, and DNA methylation increases. That is, the peak of mortality at the beginning of life is not associated with aging.
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