Standing the test of time
If as a woman you have ever taken the metro in Asia, you may have found to your delight you can actually hold the handles hanging down from the bar without dislocating your shoulder. Western men may have to slouch on crowded public transport in Beijing if they wish to hold onto them. However, some retrofitting may soon be necessary on public transport in many Asian cities, since people – and men in particular – are getting taller. Perhaps as handles adapt, some will be left that women can use.
Likewise visitors to Southern Europe who are of Northern European stock may have noticed that they can now look most people in the eye. “The midgets are dying out,” laughed Teresa, a Portuguese woman. “Those extremely short, stocky men are almost nowhere to be seen; I was afraid for my son but he’s nearly 6 foot.”
It was assumed by many that Asians and Southern Europeans were genetically smaller, but there has been a spontaneous evolution in the space of a couple of generations. The average Chinese male is now 5 foot 8 (177cm) and the average American male 5 foot 9 (179cm). Women are the same height on both continents. The assumption is that good diet has caused this sudden growth spurt, although the Chinese eat few dairy products so the explanation for the tall Dutch doesn’t seem to apply. Is there a specific genotype for tall people? Or is it all diet and living conditions?
There are of course areas of Asia where people are still significantly shorter. Interesting is the comparison between South and North Koreans, the former being 8cm taller than their Northern counterparts. This seems to be a direct result of the famines of the 1990s. The Chinese may have been bigger in the past too, to judge by the height of the Terracotta Warriors – all tall even by Western standards, standing at over 6ft (183cm), though perhaps warriors were selected because of their height. Conversely, the suits of armour in European castles seem to be made for rather short men, which correlates with the poor nutrition from which people in the Middle Ages so often suffered. Severe malnutrition is known to lead to stunted growth. Being tall has always been seen as an advantage, and today leg lengthening surgery is becoming popular in Asia, since tall people are expected to get better jobs.
Genetic determinism as far as height is concerned is therefore far from absolute. It has been observed that the heights of mother and son and of father and daughter correlate, but that is not the whole story. Height is determined by the complex interaction of genes and our environment – inner and outer. Our height depends not only on our own health during childhood, but also on that of our mother’s during pregnancy, and whether we suffered from neglect. Stress, once again, affects the body. If the stress is removed before adulthood, catch-up growth can occur, and can be significant. Diet, exercise, fitness, pollution exposure, sleep patterns, climate and even happiness are other factors that can affect growth and final height. Essentially, the developing body devotes energy to growth after other bodily and psychological functions are satisfied.
Even as adults, it is possible to change our height. The spine shortens and becomes compressed due to poor posture and gravitational pull (we are taller in the morning). It is possible to add up to 3 inches (7cm) to our height simply by stretching the spine. There are plenty of websites demonstrating what exercises help us to grow.
The changes in average heights we are observing in populations we thought were short and stocky by nature show how quickly something we thought was a genetic factor can change given the right environment.
Genetic determinism is on its way out.