The secular trend in human physical growth: a biological view
Introduction
Human biologists are well aware that the human race has been increasing in body size over the past one and a half centuries, the rate of increase depending not only on the time and place where it is measured but also on the particular measure of body size used, e.g. stature or weight. Anthropometric historians also know about these temporal changes in body size, particularly stature, but their focus is on the social factors that underlie them and they recognise—perhaps more clearly than human biologists—that the secular “trend” is not always upwards. For this reason they prefer the term secular change.
A principle underlying anthropometric history is that adult stature is a powerful proxy for childhood living conditions, with adverse conditions leading to impaired growth. Nutritionists and human biologists recognise that growth is affected by the interplay of diet and nutrition on the one hand, and morbidity—particularly infection—on the other. Yet the optimal conditions for nutrition and environment, leading to reduced rates of stunting in the developing world, have yet to be identified with any confidence.
The secular trend is of interest for several reasons. It is a marker of the public health of the population as it changes over time (Tanner, 1992), it provides insights into the link between growth and the environment (Cole, 2000b) and it illustrates aspects of the physiology of inter-generational relationships in growth and size (Emanuel et al., 1992).
The aim of this review is to focus on the secular trend as it has manifested itself since about 1850 in Europe. The emphasis here is on biology rather than social history, so that the perturbations upsetting the smooth trend are largely ignored. I summarise the evidence for secular trends in various distinct body measures, to show how they vary with age, time and space, to demonstrate that several different trends operate in tandem and to discuss briefly the factors that contribute to them.
Section snippets
Adults
The most visible expression of the secular trend is the increase in adult height seen in many parts of the world, with grown-up children being taller on average than their same sex parents. This has been happening since at least the mid 19th century, based mainly on male conscript data, for example, from the Netherlands (Van Wieringen, 1986). There mean height has increased from 165 cm in 1860 to 181 cm in 1990 and the Dutch are currently the tallest nation in the world—young men averaged 184 cm
Developmental tempo
Developmental tempo is the rate at which children mature, as measured for example by bone age or pubertal stage. The simplest and most accurate pubertal stage measure is menarche in girls, and the mean age when this occurs has been well documented in the 19th and 20th centuries. It has fallen sharply since the 19th century, as shown by data collected, for example, in Norwegian maternity hospitals (Liestøl, 1982). In 1840 menarcheal age was almost 16 years, but by 1940 it had fallen to 13.5
Weight
As with height there have been widely reported secular trends in weight from many parts of the world, both in adults and children. These trends arise from two distinct sources, increases in body size (height) and changes in body shape, which corresponds to adiposity as measured by weight-for-height or indices of regional body composition, e.g. skin-fold thickness or circumferences. So, the secular trend in weight is a combination of the trend in height, as described earlier and the trend in
Discussion
There is no doubt that secular trends in height, weight, BMI and developmental tempo have been occurring over long periods of time and in many cases continue to occur. Several aspects of these trends are of interest: first, the varied nature of the trends in terms of their timing and intensity; second, the physiological processes underlying them; and third, the environmental factors that have been driving them.
In summary, adult height and weight have been increasing more or less linearly since
References (29)
- et al.
Stature and pubertal stage assessment in American boys: the 1988–1994 Third National Health and Nutrition Examination Survey
Journal of Adolescent Health
(2002) - et al.
Compensation for a bad start: grow now, pay later?
Trends in Ecology and Evolution
(2001) - et al.
Reference data for weight, stature and weight/stature in Mexican Americans from the Hispanic Health and Nutrition Examination Survey (HHANES 1982–1984)
American Journal of Clinical Nutrition
(1990) - et al.
Variation in the body mass index among young adult Polish males between 1965 and 1995
International Journal of Obesity
(2000) - Bogin, B., 2001. The Growth of Humanity. Wiley-Liss, New...
- et al.
Prevalence of overweight and obese children between 1989 and 1998: population based series of cross-sectional studies
British Medical Journal
(2001) - et al.
Secular trends in weight, weight-for-height and triceps skin-fold thickness in primary school children in England and Scotland from 1972 to 1980
Annals of Human Biology
(1987) Galton’s midparent height revisited
Annals of Human Biology
(2000)Secular trends in growth
Proceedings of the Nutrition Society
(2000)- et al.
TV or not TV—fat is the question
Pediatrics
(1993)