Studying the physical health history of a country or region is quite a challenge, as it is difficult to find systematically collected indicators. However, we have just published a study in which we have analyzed the clear link between the health of a population and a simple and widely recorded data: body height. For most of human history, height remained relatively stable. Until 1800, the average height in Europe ranged from 165 cm to 170 cm.
But in the last 200 years, something extraordinary has happened: height has increased dramatically worldwide, but especially in Europe. In many European countries, it has increased by more than 15 cm, and this has been especially evident in the Netherlands. The average Dutch man has gone from 166 cm in 1810 to 184 cm today, an increase of 18 cm in just two centuries. In fact, Dutch men are currently the tallest in the world.
While genetics undoubtedly play a prominent role in determining individuals’ height, this tremendous change in an entire population cannot be explained solely by evolution. If it were, the height change would have occurred over a much longer timescale. However, in the last 200 years, the Netherlands, like much of the rest of the world, has experienced a huge improvement in their standard of living, from reducing excessive mortality rates and infectious diseases to greater access to high-quality food. The rapid increase in height, therefore, shows a clear relationship between the environment and healthier, taller populations.
Height, health, and development
Height and health depend on similar factors during development, the most important of which is nutrition. To grow and be healthy, people need to fuel their bodies with food. However, this energy can be diminished by other demands that divert it from growth: factors such as disease, stress, and heavy manual labor can result in shorter populations.
Recent research reveals that in the 19th century, in the Netherlands, chronic or recurrent diseases were associated with shorter adult height, while shorter and more acute illness periods could be beneficial for growth. This is probably because less severe illnesses increase immunity against future infections.
It has also been shown that the death of parents, especially mothers, led to shorter heights. In the case of very young children, this was because they depended on their mothers for nourishment, but it also occurred in older children, indicating the profound stress of losing a primary caregiver. Interestingly, although the loss of the mother was related to shorter heights in children – in the Netherlands and elsewhere – the loss of the father was not, which could be due to the gendered nature of parental care during this period.
Overall, height can be considered a reflection of the quality and quantity of food consumed by an individual during their development – and the absence of stressful factors that divert energy derived from them – from birth to the end of puberty.
Height and health in adulthood
Regarding measuring health in adulthood, height is a more complex issue. Nowadays, people taller than average, especially men, tend to have a lower overall risk of death. However, extremely tall people (190 cm and taller) are slightly more likely to die earlier than others, mainly because they have a higher risk of cancer-related mortality. This is believed to be a matter of body mass: taller bodies have more cells and more cell divisions, which means a higher likelihood of developing cancer. Additionally, taller people tend to consume more calories, which could also influence this.
When analyzing historical populations (i.e., before World War II), the results are even more complex: taller people, both men and women – even those who today would be considered relatively short, like women of 155 cm – tended to die at younger ages. These higher mortality rates were probably because taller people need more calories than shorter ones. In times of food scarcity, which were more common in the past, the latter were less at risk of malnutrition.
In historical populations, deaths from infectious diseases were also more common than today, and the combination of these two factors posed a greater risk of death for taller people.
Height stories today and in the future
While our own research has focused on the relevance of height for studying the past, it also has important implications for healthcare today, especially in hard-to-reach or follow-up areas. Currently, the World Health Organization collects data on child growth stunting, meaning if a child has fallen behind what is considered a healthy growth curve. This data is used to estimate malnutrition levels within a country or region.
In the Netherlands, children are now shorter than their parents, but it is not clear what has caused the giants of the modern world to shrink. This raises a series of serious questions: Has the quality of the diet decreased? Does childhood obesity prevent growth? Finding out why populations grow – or shrink – can help us understand health at a national, not individual, level.
Kristina Thompson, Assistant Professor, Health & Society, Wageningen University, and Björn Quanjer, Postdoctoral Researcher, Radboud University
This article was originally published in The Conversation.