So why do women go through menopause?
1. The lack of mature follicles in the ovary is the direct cause of menopause.
Ovary is the female gonad, whose main function is to ovulate and secrete estrogen, and to maintain menstrual cycle, fertility and female sexual characteristics. The undeveloped follicles in the ovary are called primordial follicles. There are about 654.38+10,000 primordial follicles in the ovaries of female newborns, only about 400 to 500 follicles mature in their lifetime, and the rest degenerate on their own. When a woman is about 50 years old, the primordial follicles in the ovary are almost exhausted. Moreover, after decades of vicissitudes, even if the primordial follicle survives, its sensitivity to pituitary hormones is obviously reduced, and it is difficult to mature and produce enough estrogen and progesterone, which eventually leads to menopause and menopause.
2. Genetic genes control the number of primordial follicles in women's ovaries. Primordial follicles are determined by genetic genes, and there are certain family differences. Therefore, the age of menopause in women is early and late. Whether the primordial follicle can develop and mature depends on various environmental factors, such as menarche age, marital status, nutrition, pregnancy and childbirth, breastfeeding, contraceptives, smoking, exercise, occupation, physique, climate, altitude, race, economic status and other factors. The age of female menopause is determined by genetic genes, and genetic genes are determined by the power of natural selection in the process of evolution. Biological characteristics selected to be preserved or enhanced must increase the number of offspring carrying these genes. However, menopause will reduce the number of children born to women. Why is this gene preserved? The failure and weakness of primordial follicles is the direct cause of female menopause. The question is: Why does natural selection arrange for women's primordial follicles to gradually fail or lack vitality in their forties? Why can't the age at which menopause begins gradually move back and disappear again? Such women can have more offspring. In fact, primordial follicle depletion is only the direct cause of female menopause, not the ultimate cause. Evolutionary history is the ultimate cause of menopause in women around 50 years old.
Menopause is the result of the extension of human life. In more than 7 million years of human evolution, only a very small number of people, both men and women, can live past 40 years old, and genes naturally arrange to terminate fertility after 40 years old (control the number of primordial follicles). The extension of human life span is only in recent decades. Given enough time (such as 65,438+0,000 years), human beings can evolve any suitable biological characteristics. The result of human evolution is often to delay rather than accelerate aging, but the aging of reproductive organs prolongs the life span of women, and natural selection in the process of evolution will strike a balance between maintaining the body and reproducing. In a very backward social environment, having too many children will shorten life expectancy, while birth control will prolong life expectancy. In modern society, women either don't have children or only have one child, and their life expectancy is obviously prolonged, at the cost of suffering from menopause, and any benefits have to pay a certain price.
4. Menopause has reduced the reproductive risk of elderly women. Even in the affluent 20th century western society, the probability of a woman over 40 years old dying in childbirth is seven times higher than that of a 20-year-old mother. In addition, the survival rate and the probability of good health of babies born to elderly women are relatively low. The older a woman is, the more children she has, the more energy she spends on taking care of her children, and every birth in the future will face greater and greater risks. Older women have less income and greater risks, but having fewer children may make more children survive.
The emergence of menopause may be beneficial to maximize the number of children. Older women have a high risk of pregnancy, and there is little chance for their children to survive healthily. On the contrary, her young children are at the best reproductive age, and their children have a high survival rate. Older women take great risks in giving birth to their own children, so it is better to help younger children take care of them. Although personal interests are sacrificed, it is beneficial to racial reproduction.
Menopausal women can spend most of their time (7 hours a day) collecting food, while teenage girls and newly married women can only spend about 3 hours a day. In addition, the harvest of labor will increase with the increase of age and practical experience. Menopausal women have no underage children to feed, so they can give food to their grandchildren. Whether it is beneficial for a woman to pass menopause or maintain fertility is clear as long as the income statements of both parties are listed.
6. Menopausal women are very important for the survival and reproduction of primitive tribes. Most modern people get information through books, TV or newspapers. In the primitive society before writing appeared, a few old people were regarded as a treasure house of information and practical experience, which was vital to the survival of the whole tribe, because the old people could clearly remember the last natural disaster and lead the whole tribe through the famine safely. These elderly people are often postmenopausal women, and men have less chance to live to this age than women.
7. Why is the menopause of modern women advanced instead? At present, many women have menopausal syndrome around the age of 35, which is called recessive menopause in academic circles. There may be the following reasons: First, the age of menarche in modern women is earlier, with an average of 12.5 years, while the average age of menarche in primitive society is 19 years. Second, the fertility has declined, because in the years of pregnancy and lactation, the ovaries do not ovulate, saving a lot of follicles. Third, the accelerated pace of life, great mental stress, lack of vitamins and trace elements, reduced physical activity, coupled with obesity, chronic diseases and other reasons, reduced the sensitivity of primitive follicles to pituitary hormones, increased atresia follicles, and decreased mature follicles. So the age of menopause is advanced.
8. Women should receive health care for menopausal women in advance, so as to delay the menopause age and improve the quality of life of menopausal women. Although genetic genes control the number of primordial follicles, environmental factors determine the number of mature follicles. Therefore, we can delay the menopause age by improving environmental factors, such as strengthening exercise, improving nutrition, improving the quality of marriage, maintaining psychological balance, quitting smoking, improving professional status, strengthening physical fitness, losing weight and so on. The health care of menopausal women should never start from the onset of menopausal syndrome, but should start from around the age of 30. At the same time, the estrogen level is measured twice a year to get a normal basic level, which can be used as a reference value to guide hormone replacement therapy in menopause, adhere to the principle of supplementing as much as possible, keep female sex hormones at a normal level, and improve the effectiveness and safety of hormone replacement therapy.