In most countries of the world, life expectancy at birth for women is four to seven years longer than for men. It seems that this greater longevity is partly due to a greater efficiency of the female immune system during aging.
In most animal species, females have a longer lifespan than males and humans are no exception to the rule: in Europe, the latest statistics indicate that the life expectancy of a girl born in 2009 is 83.3 years old, almost 5 years older than a boy (78.8). How to explain such a difference?
The longevity of women to protect the species
The more frequent adoption of risky behaviors by men (violent activities, speeding, alcohol abuse) is certainly a factor to consider; for example, accidental deaths are the main cause of death among people under 45 and these deaths mainly affect men.
But, beyond these behavioral differences, the longer longevity of women is probably a biological adaptation that comes from their essential role in reproduction: in addition to giving birth to children, women have had throughout evolution feed them and accompany them closely during the first years of life to allow them to reach adulthood. Premature mortality of women would therefore have had disastrous consequences for the survival of the species and it seems that evolution has endowed women with a biological advantage that allows them to live longer.
Hormones protect women’s hearts
The greater longevity of women is well illustrated by the later onset of serious and potentially fatal diseases. For example, while men are often affected by heart disease between the ages of 50 and 60, these diseases strike women on average 10 years later, between the ages of 70 and 80, this protection being due to the estrogens produced during adulthood. Since heart disease alone is responsible for half of all deaths, it is therefore not surprising that the select club of centenarians has five women for every man!
Immunity that resists better over time in women
In addition to this cardioprotection, recent research suggests that the immune system of women could also participate in their longer longevity. It has been known for several years that aging is associated with a decline in immune functions, an “immuno-senescence” which promotes the appearance of infections, cardiovascular diseases and cancers, and thus reduces life expectancy. According to a group of Japanese researchers, this decline in immunity is less pronounced in women: by analyzing different parameters of the immune response in 356 men and women aged 20 to 90, they observed that lymphocytes (white blood cells) and cytokines declined more rapidly in men than in women. At the same time, the increase in “killer” (NK) immune cells, which accompany normal aging, is more pronounced in women than in men. In other words, women’s immune system is better preserved during aging and can therefore better protect the body from potentially dangerous attacks.
Bad habits cancel everything
The innate biological advantages that allow women to live longer, however, should not overshadow that these protections will be useless in the face of unhealthy lifestyle choices. Smoking, for example, has increased significantly among European women in recent years and lung cancer now surpasses breast cancer as the leading cause of cancer death.
Preserving the benefit of being a woman
Not smoking, maintaining a healthy weight by eating healthily and exercising regularly therefore remain the best weapons available to women who want to take full advantage of their biological predisposition to live longer.
Hirokawa K et al. Slower immune system aging in women versus men in the Japanese population. Immun Aging;10:19.
Forgotten vegetables: think of them