The scientists combined population data on aging hundreds of species of mammals and found for all sex differences. Despite the fact that females in most cases live longer than males, not all species, they do age more slowly. The difference in mortality, the researchers propose to explain sexual dimorphism: the differences in the organisms, the male and female make them susceptible to different environmental factors. Work published in the journal Proceedings of the National Academy of Sciences.
Has long been known that women live on average longer than men. This is true not only for the species Homo sapiens in General, but also for each population separately. However, it is still unclear what this difference is owing. According to one theory, the case in sex chromosomes: recently, scientists have estimatedthat animal species heterogametes floor (from different chromosomes) live on average less than homogametic (with the same). If so, nothing special in women and men no — they just obey the General laws for animals.
At the same time, the difference in life expectancy can be caused by different reasons. Perhaps the fact that one gender because of their genetic characteristics, aging faster than the other. Ageing is now often defined as increased mortality over time (although we already talked about why it’s not the best definition). Consequently, if one sex ages quicker than the other, the curve of mortality have sharply bend up. But another possible development: one of the sexes can be just above the background level of mortality — that is, its representatives are on average more likely to die, regardless of age, and then the curve for one sex must lie higher than for the other.
To find out whether there are General mammalian pattern, Jean Francois Lemaitre (Jean-François Lemaître) from Lyon University, along with colleagues collected data on 134 the populations belonging to 101 mammal species. The authors used the open table of mortality for these conclusions, or modelled mortality based on individual data — for example, determine the age of dead animals, which we find in nature.
It turned out that female mammals live longer than males, approximately 60 percent of the population. And in most cases they have a higher than women to men: if for men the difference in life expectancy is an average of 7.8 per cent for the other mammals to 18.6 percent.
At the same time, General patterns in mortality curves, a scientist could not be found. They have identified such species in which the males age faster than females (the curve grows sharper), for example, deer, and such that faster aging female elephants. But in primates the rate of aging was almost the same, and the difference in life expectancy was caused by the difference in mortality, that is, the curve for males was above the curve for females.