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Human biologists use the
term ‘secular trend’ to describe alteration in the measurable
characteristics of a population of human being occurring over a period
of time. Over a period of at least a century biosocial changes have been
occurring in the population of much of the world which have led to:
- increase in the rate of
growth of children;
- earlier onset of
puberty, as indicated by menarche (the onset of the menstrual cycle) in
girls and the adolescent growth spurt in both boys and girls;
- increase in adult
stature, with a possible decrease in the age at which adult stature is
reached.
Although the magnitude of
changes in some countries have been fairly uniform they are by no means
universal. However, Japan has shown a particularly dramatic secular
trend. Japanese boys increased in stature by
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In decade between 1957 and 1967 |
In decade between 1967 and 1977 |
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6 years |
31mm |
17mm |
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14 years |
62mm |
35mm |
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17 years |
33mm |
19mm |
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