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The length of life

  The increase in the average life expectancy of people is the result of economic development and civilization progress, but the arrival of aging may cause some problems, such as the possibility of slowing economic growth. Regardless of whether the worry will become a reality, just from the point of view of China’s entry into an aging society, it involves the most important and ultimate question – how long is a person’s life expectancy?
  There is no ready-made answer to this question, nor is it easy to answer. However, molecular geneticist Jan Weige and his team at the Albert Einstein College of Medicine in the United States have given the limit of human lifespan – 114.9 years old, and the probability of humans surviving to more than 125 years old is less than 1 in 10,000. The results were published in the British journal Nature. The study’s conclusions are the result of an analysis of nearly 30 years of data on 75,000 people in several countries by Weegee et al. However, the findings have been criticized by other researchers, who believe there is no clear limit to human lifespans. A study of the survival records of nearly 4,000 Italians by demographers Barbi of the University of Rome and American scholar Wachter concluded that although the risk of death increases exponentially before the age of 80, after Growth will slow down and eventually stabilize. People who lived to age 105 had a 50 percent chance of living to the next year, as did those who lived to age 106, 107, 108 and 109. The results were published in the American journal Science.
  It is not surprising that the two top academic journals publish two different research results on human lifespan. The key point is that the research results need to be reproducible. Unfortunately, there are currently no overwhelming reproducible findings to support one side.
  In fact, most scientists and the public agree that there is a limit to human lifespan. “Although the tortoise has a long life, it still has its own time”, but different times have different lifespans. Even Siegfried Hakimi, a professor at McGill University in Canada who disagreed with the conclusions of Jan Weige’s research, also put forward a hypothesis: Human life expectancy will continue to rise steadily, and by 2300 the highest life expectancy may live to 150 years old. This also means that the vast majority of people will not live to 150 years old, so there is a limit to human lifespan. However, it should be acknowledged that human lifespan will continue to increase for a period of time with the development of the times. So, what factors affect the length of lifespan?
  A new study has found that longevity people have special genes in their genetic code. People who live past the age of 105 tend to share certain genetic similarities, according to a study published May 4, 2021 in the journal Digital Life. These genetic similarities improve longevity in two ways, one is that there are longevity gene mutations (more beneficial gene mutations), and the other is that there are fewer harmful gene mutations.
  The researchers took blood samples from 81 long-lived people over the age of 105 across Italy, as well as 36 healthy people with an average age of 68, and performed whole-genome sequencing on 2 groups of people. , to compare and look for genetic differences between longevity and younger age groups. It found that in the 105-year-old cohort, there were a small number of genetic mutations, and the most common of these mutations was associated with increased activity of the STK17A gene. The STK17A gene is responsible for coordinating the cellular response to deoxyribonucleic acid (DNA) damage, promoting the damaged cells towards programmed cell death. This highly active STK17A gene helps fight the development and progression of various diseases, including cancer.
  Under normal circumstances, human cells are always alive and dead, and are in a benign dynamic balance. If this balance is disrupted, people will become sick. If the dead cell does not die, it can lead to malignant growth of the cell, the formation of cancer, and ultimately the death of the body and shorten the lifespan.
  The study also found that another important shared genetic feature of longevity people is the COA1 gene, which plays an important role in the transmission of information between the nucleus and mitochondria. Previous research has found that mitochondria play a key role in age-related diseases, especially neurodegenerative diseases. Therefore, the COA1 gene has the potential to prevent neurodegeneration, help prevent Alzheimer’s disease, and prolong life.
  In addition, the 105-year-old cohort had fewer harmful genetic mutations, which could help protect them from diseases such as cancer and heart disease, and reduce the risk of disease and death.
  These studies show that longevity has a genetic advantage, however, this advantage is innate and not shared by everyone. However, can more people gain genetic advantages through acquired methods and thus become longevity? The researchers believe that it is possible to achieve this goal through drugs and genetic technology.
  A drug for the treatment of diabetes, metformin, made an unexpected discovery. First, in animal experiments, it was found that metformin can increase the lifespan of outbred SHR female mice by 37.8%. The earlier metformin was taken, the longer the lifespan of the mice was. Other studies have found that metformin can also extend the average lifespan of C. elegans. However, the results of experiments on people seem to be more convincing. The researchers conducted a controlled study of 180,000 people, of whom about 90,000 were diabetics. Some of them were taking metformin, some were taking sulfonylureas, and some were taking a placebo. After a 2.8-year observational study, it was found that diabetic patients receiving metformin treatment The survival rate was significantly higher than the sulfonylurea group, and the adjusted survival rate was even higher than that of the non-diabetic group taking placebo. However, this result has also been questioned. Diabetes patients taking metformin live longer than healthy people, is there a problem with the experimental design? According to the analysis of the experimental results in this study, the conclusion is consistent with a certain pharmacological mechanism. The mechanism proposed in this study is complex and also involves multiple molecular channels. For example, metformin can regulate the insulin/insulin-like growth factor-1 (IGF-1) signaling pathway, and by regulating this signaling pathway, it can reduce the blood sugar level of patients, slow down the aging of the body, and prolong life; Metformin can also regulate the expression of SIRTs. SIRTs are a class of nicotinamide adenine dinucleotide (NAD) +-dependent deacetylases, which participate in regulating the occurrence and progression of various malignant tumors by regulating cancer metabolism. At the same time, these substances can also regulate the function of mitochondria. , thereby extending life.
  How to extend lifespan through genetic technology? Scientists analyzed the genes of budding yeast and nematodes and identified 25 longevity genes, of which at least 15 have similar versions in the human genome. For example, SIR2 and FOXO3A are recognized longevity genes. Some researchers transplanted the SIR2 gene into mice, which extended their lifespan by about one-third. However, the quality of life of such mice is not very high, and most of their lives are lethargic.
  There is also an indispensable factor for longevity – lifestyle. Only a good lifestyle can promote and induce beneficial genes to function while suppressing harmful ones. Not smoking, not drinking, and sticking to a healthy lifestyle like regular living and exercising have an impact on longevity even more than genetics.
  The more fundamental question about lifespan is, if it is really possible to extend lifespan with drugs and genetic technology, would people be willing to do so? Are people living longer the better? Some people are willing to prolong life in various ways, but not everyone agrees that longer life is better. For example, on May 10, 2018, 104-year-old Australian botanist Goodall chose to end his life by voluntary euthanasia at a clinic in Switzerland.
  Maybe, we don’t need to worry about aging. First, the elderly also have the ability to work and live. Second, some people don’t want to live too long. Take the initiative to end your life. It is not whether a person can live, but whether he can live a healthy and happy life.

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