Dutch men and Latvian women are the planet's tallest people. The average Dutchman is now 183cm (6ft) tall, while the average Latvian woman reaches 170cm (5ft 7in).
Swedish men and women were the tallest in the world when records began in 1914. Americans, once among the world's tallest people, have dropped from having men and women at 3rd and 4th in the global height rankings a 100 years earlier, to placing 37th and 42nd respectively in 2014.
‘The height charts are dominated by European countries. Dutch men are the world’s tallest. People in the UK & US have grown taller at a slower rate. In contrast, some nations in sub-Saharan Africa, North Africa, and the Middle East have seen average height decline.’
The research, led by scientists at Imperial College London and published in the journal eLife
, tracked the growth in 187 countries since 1914. They also found some nations have stopped growing over the past 30 to 40 years, despite having spurts at the start of the century. It finds Iranian men and South Korean women have had the biggest spurts in the last 100 years, increasing their height by an average of more than 16.6cm and 20.2cm respectively.
The United States was one of the first wealthy countries to plateau, followed by others including Britain, Finland, and Japan. The height of men and women in Britain has increased by around 11 cm over the past century, while the height of U.S. men and women has risen by 6 cm and 5 cm. Meanwhile, people in Spain and Italy and many countries in Latin America and East Asia are still gaining height. East Asia has seen some of the biggest increases. People in Japan, China and South Korea are much taller than they were 100 years ago. Chinese men and women have gained around 11cm and 10 cm respectively.
In contrast, some nations in sub-Saharan Africa, North Africa and the Middle East have seen average height decline over the past three to four decades. "The parts of the world where people haven't got particularly taller over this 100 years of analysis are in South Asia (such as India, Pakistan and Bangladesh) and in sub-Saharan Africa. Here the increase in height is between 1-6cm in those regions," explained co-author James Bentham from Imperial College London. In fact, in parts of sub-Saharan Africa, average heights have actually fallen since the 1970s. Nations like Uganda and Sierra Leone have seen a few centimetres come off the height of the average man.
The height charts are now utterly dominated by European countries, but the data would suggest that growth trends in general in the West have largely levelled out. The smallest men on the planet are to be found in East Timor at 160cm (5ft 3in). The world's smallest women are in Guatemala, a status they also held back in 1914. According to the survey data, a century ago the average Guatemalan 18 year old female was 140cm (4ft 7in). Today she has still not quite reached 150cm (4ft 11in).
Some of the variation in height across the globe can be explained by genetics, but the study's authors say our DNA cannot be the dominant factor. Human height is strongly influenced by nutrition and environmental factors, although genetic factors can also play a role in individuals. Children and teens who are better nourished and live in better environments tend to be taller. Research suggests a mother's health and nutrition during pregnancy may also play a role in how tall her children grow.
Height also has lifelong consequences. Some studies have found that taller people tend to live longer, get a better education and earn more. But being tall may also increase some health risks, with studies linking height to a higher risk of developing ovarian and prostate cancers.
"This study gives us a picture of the health of nations over the past century," said lead scientist Majid Ezzati, a professor of public health from the Imperial College, London. He said the findings underlined the need to address children and adolescents environment and nutrition on a global scale.
The research team, which included 800 members, worked with the World Health Organization, used data from various sources including military conscription figures, health and nutrition population surveys and epidemiological studies.
The scientists use these to generate height information for 18 year olds in 1914 through to 18 year olds in 2014. The study also found that Dutch men are the tallest, with an average height of 182.5 cm. Latvian women are the tallest, with an average height of 170 cm