Analyzing the history of physical health of a country or region can be challenging, as consistently collected health indicators are often missing. However, our recent study explored a clear connection between population health and a simple, widely recorded data point – height.

Throughout most of human history, height remained relatively unchanged. Until 1800, the average height in Europe ranged between 165 cm and 170 cm. But in the last 200 years, something extraordinary has happened: heights have dramatically increased globally, and especially in Europe. Many European countries have seen an increase in average height of over 15 cm, and this is particularly evident in the Netherlands – the average height of Dutch men has grown from 166 cm in 1810 to today's 184 cm, an increase of 18 cm in just two centuries. The Dutch are currently the tallest people in the world.

While genetics undoubtedly play a key role in determining individual height, this enormous change across an entire population cannot be explained solely by evolution – if that were the case, the change in height would have occurred over a much longer period.

In the last 200 years, the Netherlands, like much of the world, has experienced huge improvements in all aspects of living standards, from reduced mortality rates and infectious diseases to greater access to high-quality food. Their rapid increase in height thus shows a clear link between living conditions and healthier, taller populations.

Height, health, and development
Body height and health are driven by similar factors during development, with nutrition being the most important. For growth and health, people must supply their bodies with food.

However, this energy can be depleted by other factors that divert it from growth – factors such as illness, stress, and hard physical labor can result in shorter populations.

Recent research shows that long-term or recurring illnesses were associated with shorter adults in the Netherlands in the 19th century, while shorter, one-time illnesses could actually be beneficial for growth. This is probably because less severe illnesses enhanced immunity against future infections.

Parental death, especially of mothers, was also associated with shorter height. For very young children, this would be because they depend on mothers for nutrition, but this was also true for older children, indicating profound stress from the loss of a primary caregiver.

Interestingly, although the loss of a mother was associated with shorter children's height – in the Netherlands and elsewhere – the loss of a father was not, likely due to the gendered nature of parental care in that period.

Overall, height can be seen as a reflection of the quality and quantity of food an individual consumed during development – and the absence of stressful factors that divert energy obtained from food – from birth to the end of puberty.

Height and health in adulthood
As for measuring health in adults, height is a more complex issue. Today, people above average height – especially men – generally have a lower risk of death. However, very tall people (190 cm and above) have a slightly higher risk of death, mainly due to an increased risk of cancer-related death. It is believed that this is a matter of body mass – taller bodies have more cells and more cell divisions, which means a higher chance of developing cancer. Taller people also usually consume more calories, which may also play a role.

Looking at historical populations (i.e., before World War II), the findings are even more complex: taller people, both men and women, tended to die at a younger age, even those who would be relatively short today (such as women 155 cm tall).

Their increased mortality rates were probably due to the fact that shorter people require fewer calories than their taller peers. In times of food scarcity, which were more common in the past, shorter people were therefore at lower risk of malnutrition.

In historical populations, deaths caused by infectious diseases were also more common than today, and the combination of these two factors meant an increased risk of death for taller people.

Height today and in the future
While our research focused on the relevance of height for studying the past, it has significant implications for healthcare today, especially in areas that are difficult to reach or monitor. Currently, the World Health Organization collects data on child stunting, which refers to whether a child has lagged behind what is considered a healthy growth curve. These data are widely used to assess levels of malnutrition within a country or region.

In the Netherlands, children are now shorter than their parents, but it is unclear what caused the giants of the modern world to shrink. This raises a number of serious questions: Has the quality of nutrition declined? Is childhood obesity hindering growth? Uncovering the reasons why populations grow – or shrink – could help us understand health on a national rather than an individual level.

Original:
Kristina Thompson
Assistant Professor, Health and Society, Wageningen University
Björn Quanjer
Postdoctoral Fellow, Radboud University