A group of scientists in the United States have discovered what lies behind female longevity. Apparently, the X chromosome is what influences women to live longer than men and is essential to survive.
The study conducted at the University of California, San Francisco (UCSF) says that it is believed that the second X chromosome is the cause of longevity and other benefits.
"The X chromosome, which is found only in men, contains very few genes in addition to those that create secondary sexual characteristics." The X chromosome contains many genes related to the brain and is crucial for survival. , such as male genitalia and facial hair, and is not necessary for survival, "explained a press release from this university.
In a laboratory, the researchers gave rats (females and males) four combinations of chromosomes and gonads, the two natural ones (XX with ovaries and XY with testicles) and two maids (XX in the testicles and XY in the ovaries).
The animals were identical and lived in the same environment, except for the sex chromosomes.
The rats that lived longer were those with XX chromosomes in the ovaries.
"We have long wondered what causes female longevity," said Dena Dubal, lead author of the study published in Aging Cell.
"You can imagine that nature has led women to evolve this way. When you live longer, you can really guarantee the well-being of your offspring, and maybe even your offspring," he said.
The study lasted for several years, they watched the mice for 30 months to see if they died or not.
They found that female chromosomes and female gonads prolong life in mice aged 12 to 30 months, the "equivalent in mice from middle age to old age."
Most of the effect was on the chromosomes, since the XX mice lived longer than the XY, regardless of whether they had ovaries or testicles. However, the longer living mice were those with ovaries with XX chromosomes.
"This suggests that the hormones produced by female gonads increase the lifespan of mice with two X chromosomes, either by influencing the development of the mouse or by activating certain biological pathways during their lives," Dubal said.
They compared two different types of genetically female mice (with ovaries and testicles) and found that because they had "two X's and ovaries, they allowed the mice to live longer, starting at 21 months, which is at the end of a normal life. . "
For mice that were "genetically female but hormonally male, the second X chromosome only protected them from dying before."
According to Iryna Lobach, also a teacher and part of the study, to live longer than expected, the mice needed to have ovaries and the two XX chromosomes, but to live a normal life, it did not matter if they had ovaries or testicles.
"While they had XX, they escaped premature death during aging," he said.
Dubal concluded that "when things go wrong in aging, having more of the X chromosome, along with its diversity of expression, can be really beneficial."