The ‘survival advantage’ for women has been observed over time in many different populations. However, sex differences in survival are often identified by comparing life expectancy, which summarizes median length of life, rather than years lived, and this has been interpreted to mean that “men don’t live as long as women,” the researchers explained.
The team wanted to quantify the probability of males outliving females over time and across populations, exploring the impact of changes in lifespan and variations in lifespan between the sexes.
They used a particular statistical approach, the ‘survival’ statistic, to study differences in deaths between the sexes in 199 populations from all continents over a period of 200 years. This statistic measures the probability that a person from a population with a high death rate will outlive someone from a population with a low death rate. In addition, the researchers compared how likely men were to outlive women by education level and marital status, using US national statistics on deaths and population counts.
The analysis showed that since 1850, the probability of men outliving women has varied, at all times and in all populations, between 25 and 50 percent, with only a few values above 50 percent in different countries at different times.
These were Iceland in 1891; Jordan in 1950-1954; Iran in 1950–64, Iraq in 1960–69; before 1985 in Bangladesh, India and the Maldives; and between 1995 and 2010 in Bhutan.
In other words, the data showed that between one and two in four men have outlived women over the last 200 years, challenging the long-standing notion that men simply don’t live as long as women.
In developed countries, the probability of men outliving women fell until the 1970s, after which it gradually increased in all populations. The increasing and decreasing differences in life expectancy were mainly attributed to smoking and other behavioral differences.
Men are generally more likely to live longer than women in low- and middle-income countries, the researchers noted.
The team highlighted South Asian countries, where values were above 50 percent for men in the 1950s and 1960s. In India, the under-five mortality rate was higher for girls. than for boys and has remained higher for girls in recent years. Fewer girls than boys over the age of 15 have died since the 1980s, however, “evening out” the disadvantage at younger ages, they explained.
And certain external factors seem to play a key role. For example, between 2015 and 2019, the probability of men outliving women was 40% of the entire US population, but this statistic varied by marital status and education level. The probability of men outliving women was 39 percent for those who were married and 37 percent for those who were not, and it was 43 percent for those with a college degree and 39 percent for those who were unmarried. percent for those without a high school diploma.
Furthermore, married men with a degree have an advantage over single women, educated only to a secondary level. Partners influence each other’s health, the researchers said, and this is particularly true for men, who benefit more than women from being in a stable relationship.
“A blind interpretation of differences in life expectancy can sometimes lead to a distorted perception of real inequalities [in lifespan],” they wrote.
“Not all women outlive men, even if the majority do. But the minority that don’t is not small… [the findings indicate] that 40 percent of males live longer than a randomly mated female.
However, the data showed that, in general, the mortality rate has decreased faster for women than for men under 50 years of age, especially in the first half of the 20th century; largely as a result of improvements in infant and child mortality rates.
And men have not only maintained their survival disadvantage at younger ages, but also at older ages. They are more prone to accidents and homicides in their 20s and 30s, and tend to smoke and drink more, leading to higher rates of cancer and death in their 60s.
A more nuanced approach to sex differences in survival is needed, the researchers said.
“Efforts to reduce inequalities in life expectancy must therefore be directed at various factors, causes and ages,” they concluded.