Men have grown faster than women over last century, study reveals

A new study has revealed that men across the world have gained height and weight twice as fast as women over the last century, leading to larger differences between the sexes.

The study ‘The sexy and formidable male body: men’s height and weight are condition-dependent, sexually selected traits’ was published in Biology Letters.

“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 Lewis Halsey, professor at the University of Roehampton, who led the research, according to the Guardian report.

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Halsey and his team used data from the World Health Organization, the UK, and overseas authorities records to observe the changes in height and weight compared with living conditions, which were measured by the human development index (HDI). The HDI is determined on the basis of life expectancy, time in education, and per capita income and lies between zero and one.

The records from dozens of countries were examined to determine changes in height and weight of both sexes for every 0.2 point increase in HDI. On average, women were 1.7 cm taller and 2.7 kg heavier, while men were 4 cm taller and 6.5 kg heavier.

The study highlighted that as living conditions improved, both height and weight increased in humans. However, the increase was twice as fast in men than in women.

The researchers also delved into historical height records of the UK to see whether similar trends were prevalent within countries. The data indicated that HDI increased from 0.8 in 1900 to 0.94 in 2022. On average, female height increased 1.9 per cent during the first half of the century from 159 cm to 162 cm. In males, the height increased by 4 per cent, from 170 cm to 177 cm.

“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.

Sexual preferences and taller men

The scientists also speculate that the sexual preferences of women may have driven a trend for taller, more muscular men. According to Halsey, the prime indicators of health and vitality are physique and stature. Sexual selection also prefers men who are able to protect and defend their partner and children better.

“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 faster increase in male height and weight than in females was “striking”, said Michael Wilson, professor of ecology, evolution, and behaviour at the University of Minnesota. He said that these findings were consistent with the earlier idea that females are “the more ecologically constrained” sex due to demands of reproduction, which was especially the case 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.

(With inputs from agencies)