In both humans and other mammals, the life expectancy of females tends to exceed that of males. But why? According to new research by Professor Tomokhiro Kono of the University of Tokyo, the father's sperm could be to blame.
In an investigation published today in the journal Human Reproduction , Tomohiro Kono relates how the 13 mice created in his laboratory from two female oocytes, and therefore with the genetic load of two mothers ( bimaternal mice ), live for around 186 days more than control mice born from the normal union of egg and sperm. The life expectancy measure of these rodents is 600 to 700 days, which implies that those free of sperm live 30% longer. As if that were not enough, these animals have a more active immune system than their counterparts with father and mother. Kono suspects that the reasons for this difference in longevity could be related to a gene ( Rasgrf1 ) on chromosome 9 associated with postnatal growth, and that is normally inherited from the father.
This is the first time such a phenomenon has been demonstrated in mammals, and the study authors believe it could explain why females of many species live longer than males .
