Women who believe they will live long, have sons more often than daughters, revealed a new research of British women.
According to the research, in rich Western countries the conditions of living and health of a woman influence the gender of her future kids. Earlier, this was proved only for the developing countries where women having lack of food have daughters more often than sons.
There is an explanation to this phenomenon that in this way, the evolution adaptation provides more grandchildren to people.
The principle is as follows: if the parents manage to raise strong healthy attractive son, he will bring them many grandchildren from many women. However, a boy requests more expenditures during pregnancy and the process of his being raised. For this reason, if the parents are short of resources, they should not take a risk, but give a birth to a daughter who will be able to bring them at least several grandchildren.
It is not known for sure how a woman’s body regulates the gender of a future kid. There is a theory that a woman being in a friendly environment has higher level of testosterone which helps to the male embryo to survive in the mother’s womb.
Sarah Jones from the University of Kent was researching if the ration of newborn boys and girls is caused by psychological factors, such as woman’s estimation of her life duration. Previous research demonstrated that people can estimate their life expectancy with high precision degree as it depends on their physical condition, the environment and the length of life of their parents and grandparents. Ms. Jones surveyed more than 600 women who gave a birth to their first kid in the last 4 years, from town Glostershire. The women were asked about the age of their first kid and the time when they could die.
Women who predicted long life for themselves, were the mothers of boys. The ratio of boys and girls in the group of women who thought they had 60 years and more to live, was 108:100, while among the women who said they would live less than 48 years, the ratio was 78:100.