It is a well-known truth that females live longer than males. This is true in peace or war, and even during a famine, or during epidemics. Even in animals, females live longer than males.
Scientists at the University of California, San Francisco say that they may have solved this mystery of female longevity. They have recently proposed that there is a genetic mechanism responsible for this.
As you may remember from high school biology, chromosomes are DNA molecule with part or all of the genetic material or genome of an organism. Each cell nucleus in humans contains 23 pairs of chromosomes. The chromosomes of the 23rd pair consist of two X chromosomes in most females, and an X chromosome and a Y chromosome in most males. Scientists say that the X chromosome holds the genes that control the brain which is really vital for one’s survival. Although the Y chromosome that exists only in males is the reason for their many features like facial hair, genitals and do not affect survival. The extra X chromosome may be the key to women’s longevity.
To carry out the research, the scientists gave four combinations of chromosomes - XX with ovaries and XY with testes as well as two combinations that were created in the laboratory, XX with testes and XY with ovaries to mice which were under experiment. Mice were genetically the same, also the environment was quite identical but the sex chromosomes were kept different. It was observed that mice who lived the longest were the ones where XX was combined with ovaries.
It was observed that the presence of both XX female sex chromosomes and female sexual features considerably extended the lifespan in mice. The mice having XX chromosomes lived longer when compared to the mice having XY chromosomes. But the mice who lived more were the ones who had ovaries as well as XX chromosomes (similar to natural female mice). For an expanded age, the mice needed to have ovaries working with XX. But as long as the mice had XX chromosomes, they did not die early.
Scientists say that they do not completely understand why the second X chromosome increases age. There is prior scientific research to suggest that a second X chromosome can have a protective effect. In women, half of the XX pair isn’t active in cells of the body. But when there are defects, cells with the health X compensates the defective cells of the unhealthy X.
Longer living females better ensure the well-being of your offspring. Researchers say that nature has driven females to evolve this way.