In Spain , the second oldest country on the planet, the life expectancy of women is almost six years higher than that of men: 85.8 years compared to 80.1 .
This gap is a pattern that is repeated around the world and, according to a study by public health professor Majid Ezatti and his colleagues at Imperial College London published a few months ago, the female population will even break the ceiling of the 90s in the year. 2030; Specifically, it will be Korean women who are expected to turn 90.8 years old on average.
What accounts for this difference? Scientists do not know exactly the causes . While some attributed it to the increase in heart disease among men from the 19th century, perhaps related to unhealthy habits and diet, others have suspected the missing X chromosome in men or the influence of testosterone.
New research, carried out by experts from Germany and Denmark, now tries to shed new light on the issue by focusing on the historical records of populations that have experienced different calamities, to compare the survival rate between the two sexes.
Scientists collected demographic data from former Trinidadian and American slaves, who were freed in West Africa and died heavily in the early 1800s, probably due to a lack of immunity against tropical diseases; victims of famine in Sweden, Ireland and Ukraine in the Contemporary Era, and Icelanders who suffered a terrible epidemic of measles between 1846 and 1882, among others.
Girls are more resistant
The first conclusion is that women in all those places and times lived between six months and four years longer on average than their male countrymen, despite the fact that both suffered equally the consequences of the disasters. For example, during the potato famine that struck Ireland in the mid-19th century, life expectancy for men plummeted to 18.17 years, while women lived an average of 22.4 years, when before the food crisis both groups reached 38 on average.
In addition, when analyzing the data by age group, the researchers observed that the distance was conserved in the infant mortality rates: girls were more resistant than boys. This points to biological bases to explain female longevity, which would take weight away from factors traditionally proposed to explain the phenomenon, such as the tendency to resort to violence, unhealthy habits – tobacco, alcohol, drugs … – or the riskier behaviors that usually adopt males more frequently.
The genes or hormones, then, would be the main responsible for this disparity. For example, female estrogens have been shown to boost the immune system against infectious diseases, while men’s testosterone may have the opposite effect. The mere fact of being born a woman gives more ballots to reach old age, even if they come very badly.
Source: Virginia Zarulli and others. “Women live longer than men even during severe famines and epidemics.” Proceedings of the National Academy of Sciences (2018). DOI: 10.1073 / pnas.1701535115
