Figure 1. The development of bodylength and BMI during the 20:th century.
Örjan Hallberg
Hallberg Independent Research
oerjan.hallberg@swipnet.se
Data about length and weight was obtained from Pliktverket (Military registration office) in Sweden. Figure 1 shows how these measures have developed over the years.
The BMI-value is calculated as the bodyweight (kg) divided by the body length
squared. (m2). From 1969 is noted a steady increase in BMI value.
Figure 1. The development of bodylength and BMI during the 20:th century.
In 1974 the increase starts for these 18 year old boys. Five years earlier (1969) these were 13 years old and started to spend more time in front of the TV since by then double childrens programs were introduced in TV1 and TV2. The TV-watching has continued to increase. After 1988 a new wave of BMI increase is seen, possibly connected to TV games and Internet surfing.
Figure 1shows the average body length. We can note a stable increase up to 1980 from when it seems to stabilise around 179 cm. Pliktverket notes that the share of soldiers of foreign birth has increased and those are in general shorter than the swedish natives. There is somewhat like a stepwise increase in length between 1959-1963. These 18:ers became teenagers between 1954-1958. It was during these years that FM radio and TV was distributed over the country.
Seen in a broader perspective (Figure 2) the body length has increased stepwise during the 20:th century.
Figure 2. The bodylength seen in a 10 000 year perspective.
An Austrian investigation (Dagens Nyheter 980222 p18 Sunday) has pointed out that children who are born in the summer time in average grow 6mm longer than other children.This was related to decreased melatonin production due to the sun light. A reduced production of melatonin will accelerate the growth rate.Other studies have shown that melatonin is reduced also by low- and medium frequent radiation (DN 980221 A5).
Since the radio frequent energy density has increased dramatically during the 20:th century it is therefore logical to expect to see an increased average body length due to generally reduced melatonin levels in the population.
Örjan Hallberg