How long do people usually live? Come on, everybody, 3Q.

The average life expectancy is about 80, but with the improvement of living standards and medical equipment, people will live longer. Aristotle, an ancient Greek scientist and philosopher, said: "Any animal with a long growth period has a long life." Buffon, a famous French biologist, pointed out that the life span of mammals is about 5-7 times that of the growing period, which is usually called Buffon coefficient or Buffon life coefficient. The growth period of human beings is about 20-25 years, so it is estimated that the natural life span of human beings is 100- 175 years. At the beginning of this century, Lubiler put forward that metabolic rate is related to individual size and life span, and thought that mammals with large individuals have lower metabolic rate and longer life span than mammals with small individuals. Friedlol proposed that brain development is closely related to life span. The greater the skull coefficient of mammals, the longer the life span. The human skull coefficient is 0.7, so the life span can reach 100 years. In 1960s, experiments confirmed that human fibroblasts could divide about 50 times in vitro, and then the cells aged and died. The number of cell divisions cultured in vitro is usually called the number of passages, which is related to the life span of biological individuals. Cells from long-lived individuals have more passages in vitro culture. Generally, the passage times of human cells are 40-60 times, so it is estimated that the maximum life span of human beings should be 1 10 years. In a word, although different scholars have different answers to the question of how long the natural life span of human beings is, the conclusion is basically the same. At present, it is generally believed that the natural life span of human beings should be about 120 years old. The common theories are as follows: A. Cytology: The natural life span of human body is positively correlated with the division cycle of cells cultured in vitro. Human cells divide from embryos, and the average division cycle is equivalent to 2.4 years. Human cells can divide more than 50 times on average, so it is speculated that the natural life span of human beings should be around 120 years old. B. maturity theory: human command has the same law as that of mammals. The maximum life span of mammals is 8 times-10 times of sexual maturity, and human sexual maturity is about 14- 15 years old, so the natural life span of human beings should be 1 12-65438+. C. growth period theory: any animal with a long growth period has a long life. Generally speaking, the order of mammals is 5-7 times that of their growth period, while the growth period of human beings is 20 -25 years old, so the natural life span of human beings should be 100- 175 years old.