In the midst of humanity’s profound changes, one might be forgiven for failing to notice the rise in the number of hot, cool men: those tall, broad-shouldered types who don’t tolerate self-doubt.
But according to a new study, men around the world have gained height and weight twice as fast as women over the past century, leading to greater gender differences.
Professor Lewis Halsey, from the University of Roehampton, said: “We are seeing insights into how sexual selection has shaped the male and female bodies, and how improved environments, in terms of food and reduced burden of disease, have freed us from our shackles.” .
Halsey and his colleagues used data from the World Health Organization, external authorities and UK registries to see how height and weight change with living conditions. The latter was measured by the Human Development Index (HDI), a score based on life expectancy, time spent in education, and per capita income, which ranges from zero to one.
An analysis of records from dozens of countries found that for every 0.2 point increase in the HDI, women were on average 1.7cm taller and 2.7kg heavier, while men were 4cm taller and 6.5kg heavier. This indicates that as living conditions improve, height and weight increase, but at a faster rate in men than in women.
To see if there were similar trends within countries, the researchers looked at historical height records in the United Kingdom where the HDI rose from 0.8 in 1900 to 0.94 in 2022. During the first half of the century, average female height increased by 1.9% From 159 cm to 162 cm. While the average height of males increased by 4% from 170 cm to 177 cm.
“To put this into perspective, one in four women born in 1905 was taller than the average man born in 1905, but this dropped to about one in eight women for those born in 1958,” Halsey said.
Write in Biology letters In a study titled “The Sexy, Massive Male Body: Men’s Height and Weight Are Condition-Based, Sexually Selected Traits,” scientists speculate that women’s sexual preferences may have fueled a trend toward taller, more muscular men — although at an obese age, heavy does not necessarily mean muscular.
Stature and fitness are key indicators of health and vitality, while sexual selection also favors men who are better able to protect and defend their partners and offspring against others, Halsey said.
“Women can find men’s height attractive because it potentially makes them more gorgeous, but also because being taller indicates that they are well-made,” Halsey said. “When they grew up, they were not affected by the slings and arrows in the bad environment, so they reached their full potential in height. It is an indicator that they are well made.”
The results are based on previous work found Women want taller men more than men want shorter women. But there are downsides to being tall. While tall people tend to gain more, they are also more likely to develop various cancers, perhaps because they have more cells that can accumulate mutations that culminate in the disease.
Michael Wilson, a professor of ecology, evolution and behavior at the University of Minnesota, said the rapid increase in male height and weight was “astonishing.” This is consistent with a long-standing idea that females are the “most ecologically constrained” sex due to reproductive demands, especially in mammals where pregnancy and lactation are “energy-expensive,” he said.
“The investment in larger body size by males appears to be sensitive to nutritional conditions,” he said. “When men grow up with energy-dense foods, they grow larger bodies, to a greater extent than women.