How old is the limit of human life?
How old is the limit of human life?
Through human history, the average life expectancy of humans has been increasing. More than 2000 years ago, the average life expectancy of humans was less than 26 years old. By the beginning of the 20th century, the average life expectancy of humans had risen to 49 years. Now,The average life expectancy of human beings in the world has reached over 70 years old. It can be seen that with the advancement of technology, the average life expectancy of human beings has been rising. Then there is another question here. Although the average life expectancy has been rising, is it rising?Is there an upper limit?
After studying biology, we know that cells are the basis of the human body, and genes are the basis for cells to carry out physiological activities and regulation. To put it bluntly, genes are the top priority. Genetic genes determine whether a person is healthy or longevity.To make a vivid metaphor, we compare the length of a person’s life span to the range of a cannonball. Then, the quality of the gene represents the initial velocity of the cannonball. This is easy to understand. If the gene is good, the initial velocity isHigher, the longer the range, the longer the life span, and vice versa. Then some people ask, how much can life habits affect?
Speaking of this, the example you most want to cite is this: the uncle next door has been smoking since he was a teenager, and he is now eighty years old and his body is even better. Look at the uncle in the park, he is ten years younger than him.How old is he, he does not smoke or drink, his eating habits are quite regular, but his health is not very good. The children have taken him to the hospital several times. Why is this? Lifestyle is indeed important.The influencing factors are not very important. Genes are the root. Genes are the most important factor that affects the range of a projectile. Living habits and environmental factors are only the wind direction that the projectile receives during its flight.
After a person reaches the age of 25, the vitality of stem cells is not as good as before, and the body's repair function is not as good as before. With age, people will inevitably age slowly. So what is the reason for aging?Or what are the factors that affect life span?
Factors affecting life span
Telomeres, the clock of life. There is a substance called telomeres at the top of chromosomes. Every time a cell divides, telomeres shorten a little. What is the role of telomeres? It is to ensure chromosome stability and control the mitotic cycleYes, when the telomere is shortened to the limit, the cell can no longer divide, and the senescent cell can only wait to die. An in vitro cell culture test shows that the cell division number is 50 generations.Split again, so the limit of human lifespan is the limit of telomere shortening. This is also the Hayflick limit that everyone often calls. According to this theory, the limit of human lifespan is between 120 and 150 years old.
Gene mutations and replication errors that cannot be repaired. Earlier we talked about genes that affect lifespan. Sometimes genes will make some errors when they are copied, but in most cases, these errors can be repaired by the human body.With age, the ability to repair will slowly decline. When these errors accumulate, the human body will age rapidly. This is unavoidable. When genes are mutated, they may develop malignant tumors. These are allFactors that limit life.
The exhaustion of stem cell vitality. In the previous article, we mentioned that after a person reaches 25 years of age, the vitality of stem cells is not as good as before. So what are stem cells? What is the role? Stem cells are a kind of self-renewal ability and self-differentiationCapable cells, it can continuously replenish the cells that our body needs, but as we age, stem cells will gradually age. When stem cells also age, then the body will not be able to fight aging.
Of course, there are many factors that affect life expectancy. The aging of the human body is an extremely complex process. It is a cumulative damage to cells and organs. Although medicine has studied the causes of aging for a long time, people have not been able to figure it out until now.What is the biological process of aging, and finding ways to fight aging has always been the goal pursued by medicine.
Finally, according to theoretical calculations, the limit of human life span is between 120 and 150 years. The longest-lived person in the actual record is the old French lady Jeanne Carmen, who is 122 years old.
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