Between-population variation in pre-adolescent growth.

Between-population differences in rates of physical growth and development and attained body size are well documented, but it is difficult to determine the extent to which these differences can be attributed to genetic and environmental factors. The greatest differences are to be found between populations in industrialised and non-industrialised nations, and between well-off and poorer groups within countries. Although genetic factors cannot be discounted, such differences can largely be attributed to differences in environmental quality experienced, influencing growth largely through differentials in nutritional well-being and exposure to, and treatment of, infectious disease. Growth patterns of well-off populations and groups of high socio-economic status are less heterogeneous, but differences between major global population groupings may still exist, bringing into question the validity of the concept of an international reference for the growth of young children. In this article, information pointing to genetic differences in the growth of children of different populations is summarised, and the acceptability of the NCHS (National Center for Health Statistics, 1977) references for height by age for international use is examined. It is concluded that the growth patterns of all major population groupings are likely to have similar genetic potential, with the exception of Asiatics. However, there are no data on either secular trends or well-off groups from populations that have until recently been genetically isolated, and it is not known whether they share the same potential for growth as the major populations that surround them. In addition, very little is known about the genetic potential for growth of Aboriginal populations in Australia, or in Pacific Islands populations. It is suggested that the growth references for height by age in current international use are at best only imperfect yardsticks for nutritional assessment.