Barry Bogin has written a marvellous explanation about why we go through
the adolescent growth spurt (‘Why must I be a teenager at all?’, 6 March).
We can equally marvel at another spurt not often mentioned by biologists
and anthropologists, namely the mid-childhood spurt occurring between ages
six and eight. It varies in magnitude and shows itself as a mere blip on
Bogin’s growth rate curve, but it has a very interesting history.
First, it is an opportunity for body growth to get its due after so
many years of devoting unequal resources to growing a large brain. Every
parent will attest to the struggle of dressing children and the seeming
incoherence of a clothing industry that makes pullovers to fit little bodies
that have to pull them over a brain which is nearly 95 per cent of its adult
size at 6 years of age.
Second, this spurt is related to the adolescent spurt in developed nations.
Puberty is not only the time of accelerated growth, it marks the beginning
of the end of growth too. In order for adolescents to reach the normal height
for their population they must be so far along by the time puberty hits
them. Thus for children with relatively short pre-pubertal growth periods,
an extra push is needed early on (the mid-childhood spurt) to get them to
their right preadolescent height before the pubertal growth spurt.
Children of populations with puberty closer to 16 years of age, such
as those of some underdeveloped nations, do not experience the mid-childhood
spurt because they have more prepubertal time to grow up.
Tim Bromage City University of New York