The report presented at the University of San Francisco (UCSF) has attributes of the second woman X chromosome, women in men, the cause of female severity and other physiological advantages.
Human Y chromosome has certain brain genes and it is essential to survive, the study said.
According to experiments with mice, scientists have analyzed the effects of many mammals with X X-X chromosomes, Y.
In terms of the biological wealth provided by female X chromosomes, male Y "secondary sex characteristics, such as male genitals and facial hair, have no genes and do not need to survive," says the publication. .
"We have long thought of female survival," said Dena Dubal, UCSF's assistant neurology lecturer and principal author of research, published in the Scientific Aging Cell magazine.
"It seems incredible for women to evolve in this way, and when you live, you can guarantee the well-being of your children and perhaps their descendants," said Dubal.
The researchers compared the laboratory mice with four chromosomes and gonadal combinations (the organs comprising male or female gametes), which were found in two natures -XX-ovaries and XY -tutullivist- and two in the laboratory.
When manipulating a gene, the combinations were placed in the XX chromosomes in testosterones and XY chromosomes in the ovarian.
"Mice were genetically identical, except sex chromosomes, but everything else, including the environment, was the same," said the research.
In apple XX chromosomes they obtained the longest life in their ovaries, and they exceeded the average life of 21 months and reached 30 months.
The 20-gene established in the guns avoided the premature death of animals, but they prolonged one month's life.
"In the long run, the mum must have two XX chromosomes, depending on the natural order," said Iryna Lobach, UCSF epidemiologist and bio-host, assistant professor and co-author of the report.