Czechs walk tall into the new century
It might be the case in your community, too: children are taller than their parents, who themselves outgrew their parents in terms of physical height. During the last century, each successive generation in most of the industrialised world has been growing taller than the generation before it. On average, young adults today measure one inch more than their parents and two inches more than their grandparents.
Regular anthropometric studies first started in 1951, and since then new figures have been gathered and compared every ten years. But the very first such research took place much earlier - in 1895 actually, conducted by the founder of Czech anthropology, professor Jindrich Matiegka. It covered around 100,000 children between the ages of six and fifteen.
The latest study was the sixth of its kind in this country, and it covered 55,000 kids between birth and sixteen years of age. Jana Vignerova from the State Health Institute was in charge of the research:
"Because we can compare our data with a research conducted more than one hundred years ago, in 1895, we know that the bodily height of the Czech population has increased sharply. After World War Two the growth was very rapid, but gradually the trend is stopping. We can see that, compared to 1991, the average height of children has not increased."
The data also shows that, compared to 1895, twelve-year old boys are today taller by some seventeen centimetres, and girls have outgrown their nineteenth century peers by almost nineteen centimetres. What is behind such a dramatic change?
"It is definitely living conditions in which the children are growing up. Nutrition and health care are the most important factors. There are other things, as well: genetic factors, a pleasant psychological environment and so on."
Bodily height is a result of a complex interplay between genetics, nutrition, emotions and illnesses. It is estimated that only seventy percent of our final height is influenced by our genes, while the rest depends on the environment in which we grow up. A balanced diet, healthy pregnancies, optimal medical care and high social standards result in a greater height. Children from urban areas whose parents have reached higher levels of education also tend to be taller than children from rural areas whose parents have only basic education.
Worldwide studies suggest that the long-term increase in bodily height is levelling off and that, once they complete growth, today's healthy and well-nourished boys and girls will have reached the maximum height allowed by the human genetic potential.
"One of the theories is that our genetic potential has been exhausted and we can say that our living conditions are optimal. Not that they could not be improved even further, but it is not really feasible. It is therefore most likely that bodily height will not increase."
Jana Vignerova from the State Health Institute adds, though, that while Czech girls probably won't be any taller in the future, boys are still increasing their height slightly.
In general, boys and girls, from birth, display markedly different patterns of growth. Girls start growing earlier and also complete their growth ahead of their male peers. Today's boys reach their final height at around eighteen, while girls stop growing between sixteen and seventeen years of age. That is to do with an earlier onset of puberty, which today starts some four years earlier than one hundred years ago. That also means that the twenty-year olds at the turn of the century were still growing.
Another member of the team that carried out the latest study is Pavel Blaha of the Faculty of Natural Sciences of Charles University.
"The difference between the male and female adult and adolescent population in the Czech Republic is twelve to thirteen centimetres. We can say that over the last century the average height of our boys and men has increased by twelve centimetres, and in girls and women it is six to seven centimetres."
The increase in height goes hand in hand with an increase in weight. Although the Czech media often raises alarm that - owing to junk food and an increasingly passive lifestyle - Czech kids are becoming fat, the researchers have found no evidence of such a trend.
"Our research has not proven a significant increase in the number of overweight children. What is growing is the number of overly obese kids, but their condition is often caused by metabolic or genetic disorders. Certainly, the situation is not critical with our children."
Pavel Blaha agrees fully with Jana Vignerova, but adds that perhaps more alarming than obesity in children is its very opposite.
"In our country the percentage of overweight children has not increased. There has been only a slight increase in the number of obese children. On the other hand, there has been an increase in children with low bodily weight. This could be the result of various mentally-induced eating disorders or it can sometimes be a signal of an incipient disease in the child."
Height and weight were not the only quantities measured in Czech children during the nationwide study two years ago. Anthropologists had noticed another change in the appearance of the Czech population - the shape of the skull. While most middle-aged Czechs are characterised by round faces and heads somewhat flatter at the back, young people born since the 1980's tend to have narrower skulls.
"As part of the study we measured the proportions of the head. Five years ago we found out that the proportions of the skull in Czech children had changed almost overnight. The head has become narrower and longer. It means that the face too has become narrower. That is the most significant result of the research."
And why that particular change took place - no one knows!
With the study concluded, Pavel Blaha says it is not an end in itself. The data on how the population's measurements are changing can serve a number of purposes.
"The referential data we have been gathering during the nationwide studies are important for a number of mainly medical purposes: especially for paediatricians, endocrinologists or nutrition specialists. Anthropological studies - which inform us about the development of various bodily parameters in our population - should be taken into account above all by the consumer industry, shoemaking and clothing industries and by manufacturers of school furniture. There are significant shortcomings in this area. If first-graders sit on the same chairs and in the same desks as kids in the fifth grade - whose height has meanwhile increased by twenty-five centimetres - you can work out why the percentage of children with back problems is increasing. Unfortunately, our furniture designers do not pay attention to the changes and have not worked them in."
We have to wait another ten years to see whether the conclusions of this last research will be confirmed or will have to be revised - and whether nature or nurture will have the last word.
