A notable difference between the sexes. According to a British study published this Wednesday, January 22, in the scientific journal Biology Letters, men around the world have gained height and weight twice as fast as women over the last century.
To make this observation, researchers from the University of London of Roehampton analyzed the variation in the height and weight of individuals according to changes in living conditions, evaluated in turn using the Human Development Index (HDI). The scientists used data from the World Health Organization, foreign authorities and British records.
A “surprising” difference
“We gain insight into how sexual selection has shaped the male and female body and how environmental improvement, in terms of diet and reducing disease burden, has freed us from our impediments,” said Professor Lewis Halsey of the University from Roehampton to the British media. exit The Guardian.
So while living conditions have improved in the general population for both men and women, the impact on height and weight has been twice as significant for men. For Michael Wilson, professor of ecology, evolution and behavior at the University of Minnesota, this difference is “surprising.”
According to the analysis of data from dozens of countries, for every 0.2 point increase in the HDI, women were on average 1.7 cm taller and weighed 2.7 kg more. The men were 4 cm taller and weighed 6.5 kg more.
Scientists take a more concrete example from the United Kingdom, where the human development index increased from 0.8 in 1900 to 0.94 in 2022. If the average height of women increased by 1.9%, going from 159 cm to 162 cm from 1900 to 1950, that of men increased by 4%, going 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 that figure dropped to about one in eight women born in 1958,” the study’s author analyzed. Lewis Halsey. Guardian.
Therefore, the study suggests “that as the social and ecological conditions of nations improve, (…), the height and weight of individuals increase, but more than double in men than in women, which which translates into an increase in population density”. .
Pregnancy and breastfeeding “costly in energy”
For Professor Michael Wilson of the University of Minnesota, these results confirm that the female sex is “the most limited” due to the demands of reproduction. Even more so in mammals: pregnancy and lactation are “costly in energy.”
“Men’s investment in larger body size appears to be sensitive to nutritional conditions,” he added. “When men grow up on more energy-rich foods, they develop larger bodies, to a greater extent than women.”
The study states that it “confirms Tanner’s proposal that height is a useful biomarker for assessing population health,” however, specifying that these results should be interpreted “with caution.”
Source: BFM TV
