Amid the profound changes humanity has witnessed, one might be forgiven for failing to notice a rise in sexy and formidable men: those tall, broad-shouldered types that are strangers to 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, driving greater differences between the sexes.
“We’re seeing insights into how sexual selection has shaped the male and female body and how improved environments, in terms of food and a lower burden of disease, have freed us from our shackles,” said Prof Lewis Halsey at the University of Roehampton.
Halsey and his colleagues used data from the World Health Organization, overseas authorities and UK records to see how height and weight have changed with living conditions. The latter was measured by the human development index (HDI), a score based on life expectancy, time in education and per capita income, which ranges from zero to one.
Analysis of records from dozens of countries found that for every 0.2 point increase in HDI, women were on average 1.7cm taller and 2.7kg heavier, while men were 4cm taller and 6.5kg heavier. This suggests that as living conditions improve, both height and weight increase, but more than twice as fast in men than women.
To see whether similar trends played out within countries, the researchers delved into historical height records in the UK where HDI rose from 0.8 in 1900 to 0.94 in 2022. During the first half of the century, average female height increased 1.9% from 159cm to 162cm, while average male height rose 4% from 170cm to 177cm.
“To put this in perspective, about 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.
Writing in Biology Letters in a study titled “The sexy and formidable male body: men’s height and weight are condition-dependent, sexually selected traits”, the scientists speculate that women’s sexual preferences may have fuelled a trend for taller, more muscular men – although in an age of obesity, heavy does not necessarily mean muscular.
Stature and physique are prime indicators of health and vitality, Halsey said, while sexual selection also favours men who are better able to protect and defend their partners and offspring against others.
“Women can find men’s height attractive because, potentially, it makes them more formidable, but also because being taller suggests they are well-made,” said Halsey. “As they’ve grown up, they haven’t been affected by the slings and arrows of a bad environment, so they’ve reached more of their height potential. It’s an indicator that they’re well-made.”
The findings build on previous work that found women want taller men more than men want shorter women. But there are downsides to being tall. While taller people tend to earn more, they are also more prone to various cancers, possibly because they have more cells that can accumulate mutations which culminate in the disease.
Michael Wilson, professor of ecology, evolution and behaviour at the University of Minnesota, said the faster increase in male height and weight was “striking”. He said it was consistent with a long-standing idea that females are “the more ecologically constrained” sex because of the demands of reproduction, particularly in mammals where pregnancy and nursing are “energetically expensive”.
“Investment in greater body size by males appears to be sensitive to nutritional conditions,” he said. “When men grow up with more energy-dense food, they grow bigger bodies, to a greater extent than women.
