It’s not just genes, diet or exercise that determine children’s physical development – they also need love, hope and happiness to grow tall, new analysis by an expert suggests.
A young person’s emotional wellbeing is critical for preventing stunted growth, said Professor Barry Bogin, a biological anthropologist at Loughborough University, who has been studying how humans grow for almost five decades.
He said not being loved by a child’s nearest and dearest – and lacking any hope for the future – causes “toxic emotional stress” that can harm the body, “including blocking hormones needed for growth and height”.
“The human species requires strong social and emotional attachments, that is love, between younger and older people (and) indeed between people of all ages,” he said.
“These attachments are required to promote nearly all biological functions, such as food digestion and absorption into the body, a good immune system, and an overall happiness and positive outlook on life.”
He said Guatemala, for example, where citizens live in uncertainty, political turmoil and are exposed to violence, has some of the shortest people in the world – while the Netherlands, which has policies supporting the social care and security of its citizens, has some of the tallest people.
The average Guatemalan man is around 163cm tall and the average woman grows to around 149cm, compared with the Netherlands, where men average around 183cm and women 169cm.
Professor Bogin analysed the historical records of height spanning nearly two centuries from the 1800s to the 1990s.
This covered the Long Depression – a period of global economic recession that lasted from 1873 to 1879, and saw households facing hardships such as famine and illnesses.
Data from historical records of the heights of soldiers, conscripts and prisoners showed men born in the US in 1873 were around 3cm taller than those born in 1890 – the aftermath of the economic crisis.
In the UK, the average height of men also stagnated during the same period – showing a slight rise of 1cm from 1873 to 1880 followed by a similar decrease from 1880 to 1890.
After that, the average male height increased rapidly for every year of birth, from around 169cm in 1890 to 177cm in 1960 in the US and from around 167cm in 1890 to just over 176cm in 1960 in the UK.
Prof Bogin said the data suggested height is a “sensitive indicator of economics in times when there were no economic data, especially for the working class”.
He said in cases like these, genetics, diet and physical activity cannot explain the changes in height.
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However, Prof Bogin also added other periods of global crisis, such as the Great Depression of the 1930s as well as the first and second world wars did not have a similar impact on height.
He said this was possibly because the UK and US governments had massive public works programmes in place.
“They didn’t make a lot of money but having a job and a livelihood is essential to self-esteem, and hope for the future,” he said.
His review has been published in the Journal of Physiological Anthropology.