html In the mid-120th century, aging was described as a trade-off between reproductive and cellular maintenance. Initially, the bodies of organisms use their resources to grow and maintain our health – to maintain our cells. Throughout childhood and adolescence, the focus is on staying energetic and being as strong and healthy as possible. After sexual maturity, priority is transferred to reproduction. Because, for most organisms, resources are limited and priority production of offspring may come at the expense of health. This article is original from Transformational Medicine Network. Please indicate the source for reprinting
Author: Sophia
Natural selection
1 In our lives, our genes will be mutated. Some are completely random, and may be the result of external factors such as diet or UV. Take a salmon as an example, which swims upstream and lays eggs, and then dies quickly. All is to give the salmon the best chance to reach the spawning site, and once it gets there, it will make the most of this opportunity. The possibility of salmon swimming back downstream, living at sea for a year longer, taking the same return journey and successfully laying eggs again is so small that natural selection will never favor these individuals. But anyway, they have successfully passed their genes once.
But the current understanding of the causes of death in things is relatively specific. When an organism reaches sexual maturity, the power of natural selection weakens, the aging process begins, and eventually leads to death. But it's not to make way for the next generation, said Alexei Maklakov, a professor of evolutionary biology and biological geriatrics at the University of East Anglia in the UK, which could be "attractive from an altruistic perspective".
However, not all creatures are as extreme as the only salmon that lays eggs. Some creatures do survive for a while in order to have more offspring. And most mutations in our DNA have negative effects. Our bodies are able to repair some DNA damage, but due to the weaker power of natural selection, our repair ability decreases with age.
However, in later stages of life, senescent cells accumulate in tissues, causing damage and inflammation, and are a precursor to age-related diseases. Aging and death then occur in two ways—the accumulation of negative mutations due to weak natural selection, and the mutation that may be beneficial to reproduction but not to longevity. An example of the latter may be a BRCA gene mutation. These are known to significantly increase the risk of breast cancer and ovarian cancer, but are also associated with higher fertility in women carrying these mutations. Therefore, mutations in the BRCA gene may provide reproductive advantages early in life and subsequently present greater health risks later in life. However, because natural selection weakens after sexual maturity, the advantage of reproduction outweighs the disadvantage. "Everything that happens early in life will exceed everything that happens after reproductive age, because reproductive potential is really important," said Caitlyn McHugh, a biologist at at Oregon State University. "Herbia senescence may be another example of early life advantages and later years of disadvantage. Aging protects us from cancer because it prevents DNA-damaged cells from reproduction. However, later in life, senescent cells accumulate in tissues, causing damage and inflammation, and are a precursor to age-related diseases.
Although most species age, there are some exceptions. For example, many plants exhibit "negligible aging" and some species are known to survive for thousands of years. A particularly strange example is Pandot Tree in the Fish Lake National Forest in Utah. This tree is actually a group of male trembling poplar connected by a single root system. It covers over 100 acres (400,000 square meters) and has an estimated weight of more than 6613 tons (6,000 tons). Some estimates suggest it may have more than 10,000 years of history.
Hydra's close relative, immortal jellyfish , there is another clever way to ensure longevity - if hurt, sick or stressed, it can recover from adulthood to early polyp stage.
According to a study by UCL , women with regular sex start menopause later in . They think this is an example of a trade-off – without the chance of getting pregnant, the energy consumed by ovulation can be better utilized by other parts of the body.
But in the animal kingdom, for example, bat with more offspring lives shorter than those with fewer offspring. Maybe, if there is a chance to reproduce, they will devote everything to it. McHugh said: " has this trade-off in time, and organisms that reproduce well in the early stages of life don't perform that well later in life. " (Again, our Hydra is an exception to this rule. Their fertility rate does not seem to drop in their lifetimes.)
There are also some species with very different life spans between sexes. Typically, kings or queens of ant , bees and termites may have higher fertility and longevity compared to sterile workers. In their case, why does breeding cost not reduce their lifespan? The answer may be that the king or queen is protected from many threats faced by workers, and the difference between their two lifestyles is so great that the aging theory does not apply to them.
Grandma hypothesis
3 If reproduction has such a great impact on our lifespan, why can humans live for so long after many of us stop giving birth?
grandma hypothesis shows that it is important for older relatives to stay alive because fertility is an expensive and risky business. grandmother can ensure the survival of some of her own genes by investing in her grandchildren, so a longer life span can bring an advantage from a natural selection perspective. “Families with grandmothers around have much higher reproductive health, which may be because mothers can focus on having more children, and grandmothers will help raise children who are already there,” Kountourides said. But because grandchildren only share 25% of the genes with their grandmother, their relationship with grandmother is just like her relationship with niece and nephew.
"It may also be that only because there weren't enough women in the past who survived at 50 and were unable to have children at 50. Therefore, the choice of what happens to women at 50 is very, very low," Markrakow said. " returns to the core principle of aging - natural selection weakens after reproduction. Many things that happen to us in later years may not be pleasant - but there is also no strong evolutionary power to help protect us from it. ."
Reference:
https://www.bbc.com/future/article/20220805-why-do-we-die
Note: This article is intended to introduce advances in medical research and cannot be used as a reference for treatment options. If you need health guidance, please go to a regular hospital for treatment.
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