WHEN two security guards in Dalian in north-east China got their first month’s pay packet earlier this year, they questioned why each received different amounts for identical work. The company responded that one man was 5cm (two inches) taller than his peer. Workers over 180cm earn more, they said, because bigger guards make people feel safer.

Stature is often a desirable attribute of guards, but in China height requirements are routinely specified for jobs which seem to have no need of them. To study tourism and hotel management at Huaqiao University in Fujian province, men topping 170cm are favoured, and women over 158cm. A post as a female cleaner in Beijing is advertised to women of at least 162cm. Many companies are less explicit about such demands than they used to be, but candidates often list height (and weight) on their curricula vitae.

The height premium is most pronounced for women, according to a study from Huazhong University of Science and Technology. It found that each centimetre above the mean adds 1.5-2.2% to a woman’s salary, particularly among middle- and high-wage earners. A group at China University of Political Science and Law is working on a draft law against employment discrimination for height and other physical characteristics.

Ever more Chinese are rising above such constraints, however. A 45-year-old man in China today is around 5cm taller than 30 years ago, according to the RAND Corporation, a think-tank. Soldiers are growing too tall for the diminutive tanks favoured by the People’s Liberation Army; in 2010 the government raised by 10cm the height under which children in China travel free on trains (a rare scheme that benefits the small).

Greater heights mostly reflect greater incomes. Richer people tend to eat more and live in cleaner, better homes. Meat consumption per person has increased more than fourfold since 1980. Infant mortality is less than a tenth of what it was 60 years ago. Household size has also helped. Historically people from big families have been shorter (not just in China) because food supplies must stretch further. In China the birth rate fell sharply from the 1970s nationwide.

But there are differences across the country which partly reflect the uneven benefits of the economic boom. Eighteen-year-olds from the richest cities are on average 7-8cm taller than those from the poorest ones. The height gap between prosperous and impoverished rural areas is similar. Southerners have long been shorter than northerners. Although the difference between rural and urban heights has narrowed since 1975, other discrepancies persist. The World Health Organisation says around 20% of children in poor rural areas are “stunted”, a common indicator of chronic malnutrition. This compares with 2.5% of city children. Employers’ preference for high and mighty staff exacerbates that inequality. It is time they grew up.