INTRODUCTION

The first longitudinal growth study dates back to 1759 when Count de Montbeillard measured the body length of his son from birth to 18 years (Scammon, 1927; Tanner, 1962). Actually, when studying growth, there are two basically different approaches: longitudinal and crosssectional studies. In longitudinal growth studies, we measure the same children over several years at regular intervals (as was done by de Montbeillard) in order to be able to establish individual growth patterns. In cross-sectional growth studies, we measure children of different ages only once. A plot of the average height obtained at each age (or age group) depicts the average growth pattern in the sample. One should realize that the shape of the curve seen in an average growth pattern is different from the shape of individual growth curves (Hauspie, 1989). The information provided by the longitudinal and cross-sectional approaches is quite different. Both methods have their advantages and limitations. Whether the data concerns individual or average growth patterns, we are dealing with a series of measures of size (height or average height, for example) at particular ages, either precise chronological ages (in case of longitudinal studies) or mid-points of age classes (in case of cross-sectional studies). However, the researcher is quite often interested in determining the underlying continuous process of growth, from which he wants to derive certain characteristics, such as the age at maximum velocity at adolescence, for example.

The inhabitants of the Near East, North Africa and the Indian subcontinent have been grouped together here under the name Tndo- Mediterranean’. They have much in common physically, though there are also differences. We include the dark Hamites and Indo-Dravidians along with Egyptians, Kuwaitis, and Libyans. Even within India itself, Guha (1944) distinguished 51 different ethnic groups. However, as far as child growth is concerned, it seems that the principal dissimilarities are brought about by socioeconomic differences rather than by minor ethnic variations. Mediterranean peoples dwelling on the northern shores of the Mediterranean Sea have already been considered in Chapter 2, dealing with Europeans.

The growth studies

As can be seen in Table 7, data from these population groups are not numerous. From Egypt there is a growth study of the Egyptian Nubians (El-Nofely, 1978) who were resettled after the construction of the High Dam south of Aswan City. Whereas formerly they lived in small villages, they now live in urban centers. Two groups speak dialects of the Nubian language: the Kenouz and the Fededji; the third group are Arabic-speaking. There are new studies from mostly Arabic-speaking peoples in rural Khartoum (Sukkar et al., 1979), from schoolchildren in Libya (Abounaja & Gilmour, 1985), from infants in Israel (Palti et al., 1981, 1982) and from groups in various areas in India. These latter comprise children in private schools (Sidhu, Bhatragar & Dubey, 1982; P. Malhotra, unpubl.) and another group of lower socioeconomic school children (Singh, Sidhu & Malhotra, 1987) both in Patiala City, Punjab; infants in Chandigarh, Punjab (Bhalla, Kaul & Kumar, 1986); boys in Calcutta (Pakrasi et al., 1988) and Bod boys of Ladakh (Malik & Singh, 1978).

As in the first edition, Europeans in Europe have been chosen as the baseline population against which comparisons will be made with other world populations. The reason for this is the large number of investigations that have been carried out on Europeans in the past using standardized techniques. Europe also has the advantage of a population that is close to being genetically homogeneous. European populations do vary considerably in adult size, however, and this variation also is seen in the size of the children.

Selection of European studies

One of the main difficulties in making a comparative growth survey is that the various samples of children are rarely comparable in the strictest sense. Different investigators have often used different methods, not so much of measuring technique, but of sample size and selection, age grouping, number of measurers, and area sampled. For this reason, we have never pooled data from different studies in a country to calculate a national average. In some countries genuinely national samples have, been measured, and when these are available, we have used them. When they are not, we have used urban samples in preference to rural ones, for all the evidence at present shows that when there is a difference, children in cities grow better than those in rural areas. At times when we have found two good studies from the same country, we have recorded both in the tables.

Many countries collected and analyzed new data in the 1970s and 1980s and only these are presented here in Table 2. Data from 1955–70 will be found in the first edition of this book.

As we said in the first edition, geography alone is the reason for grouping inhabitants of the Pacific Islands together under one chapter heading. Ethnically, there are such dissimilar physical types as Australian Aborigines, Polynesians, Melanesians, Micronesians, Negritos and probably mixtures of at least the last four. The Australian Aborigines always have presented classification problems for anthropologists (Montagu, 1960, pp. 440–3).

The growth studies

In Chapter 3 we considered the European populations of Australia and New Zealand; in this chapter we discuss the aboriginal inhabitants of those areas (Table 8). There have been new studies of the growth and nutritional status of Australian Aborigines in the Kimberley region of Western Australia by a group of reseachers in Perth (Gracey et al., 1983, 1984; Gracey & Sullivan, 1988; Hitchcock et al., 1987). The authors state that the people live in a wide range of conditions, from remote, partly tribal communities to partly urbanized groups outside of country towns. All school-age children are enrolled in school although absenteeism is very common. The group of infants included some nontraditional Aborigines living in towns. There also are some data from two aboriginal settlements in eastern Australia: Cherbourg, near Brisbane, and Palm Island in Queensland (Fysh et al., 1977).

From New Guinea we have new data on the Bundi (Zemel & Jenkins, 1988) which form part of a larger survey of health and nutrition in villages and urban areas by the Papua New Guinea Institute of Medical Research. We also have new data from Pere village on the island of Manus (J. Schall, unpubl.).

Disease and malnutrition continue to be the major problems of Africa's children. Droughts and other natural disasters in various regions (Abbas, 1978) civil wars and guerrilla warfare have exacerbated these problems. Many international agencies such as the World Health Organization, the United States Agency for International Development, United Nations Children's Fund and Oxfam have been attempting to help in development and education, and relief when necessary. Some countries are also using their own resources for programs in maternal and child health and nutrition education.

Intestinal parasitism is widespread in Africa. We now know that infestation with Ascaris lumbricoides affects nutrition and growth of children. Not only do parasites deprive their hosts of nutrients, they impair intestinal absorption of fat, nitrogen and vitamin A and may reduce food intake (Crompton & Nesheim, 1982).

Unfortunately, we do not have data, as we had for European and European-derived populations, to assess whether secular increase in size has taken place in specific African populations. We have no new studies on the same populations that we reported in the first edition. However, some investigators have considered secular change in Africa. Billewicz & McGregor (1982) have pointed out that in 25 years there has been no secular increase in the Gambian villages of Keneba and Manduar. Prazuck et al. (1988), comparing the individual tribal groups, reported no change in adult male stature in Mali since 1885.

There are many new data from different regions, coming from well-off, rural and tribal groups. In general fewer parameters have been reported than for the groups we discussed in the first edition. Here we have mostly weight, height, arm circumference and triceps skinfold.

So far we have been concerned with body size and shape as exemplified by height, weight and their relationship. But growth is a movement through time, and progress may be fast or slow. Two children may reach an identical ultimate height, but one with a tempo of growth (to use Franz Boas’ phrase adopted from classical music) which is slow, another with a tempo which is rapid. One girl reaches menarche, the first menstrual period, at 11.0 years, another at 15.0 years. Within a particular population final adult height is not related to the speed with which it is reached; on average, early and late developers end up almost exactly the same in height. Even in shape there is only a small difference, late-maturers ending usually as more linear people with a lower weight-for-height.

Thus tempo of physical development has to be studied separately from body size; there are differences in tempo between populations and no a priori reason why these differences should be related to differences in height and weight. Rate of maturation in body size may be measured by the percentage of mature height reached at successive ages, but this is only known for any individual after his whole growth has been completed. More widely used measures of maturity, therefore, are skeletal maturity (or bone age), dental maturity and pubertal maturity (or secondary sex character age). These measures are not dependent on childhood or adult body size. Each measure reaches the same final point in all normal persons (unlike height and weight).

A child's growth rate reflects, perhaps better than any other single index, his state of health and nutrition; and often indeed his psychological situation also. Similarly, the average values of children's heights and weights reflect accurately the state of a nation's public health and the average nutritional status of its citizens, when appropriate allowance is made for differences, iiany, in genetic potential. This is especially so in developing or disintegrating countries. Thus a well-designed growth study is a powerful tool with which to monitor the health of a population, or to pinpoint subgroups of a population whose share in economic and social benefits is less than it might be. Indeed as infant mortality rate goes down during a country's development, so the importance of monitoring growth rate increases.

There is no guarantee, however, that all populations have the same growth potential. There are certainly large differences between populations, in height and weight and the age of puberty for example, and it is now clear that a portion of these differences is genetic in origin, a portion (in the developing countries a large portion) environmental.

The first edition of this book, published in 1976, was the outcome of the International Biological Programme (Human Adaptability Section) which extended over the years 1964–74 under the auspices of the International Council of Scientific Unions. This worldwide effort resulted in 340 growth projects in 42 countries, and we made use of these, as well as other data, in a tabulation and summary of growth in populations around the world.

The ultimate size and shape that a child attains as an adult is the result of a continous interaction between genetical and environmental influences during the whole period of growth. Such interaction may be complex. Two genotypes which produce the same adult height under optimal environmental circumstances may produce different heights under circumstances of privation. Thus two children who would be the same height in a well-off community may not only both be smaller under poor economic conditions, but one may be significantly smaller than the other. This type of interaction, called non-additivity of genotype and environment, may be quite detailed and specific in its effects. If a particular environmental stimulus is lacking at a time when it is essential for the child (times known as ‘sensitive periods’), then the child's development may be shunted, as it were, from one line to another. We know, as yet, little of the details of such interactions, but quite enough to make oversimplified models scientifically suspect.

Statements about the relative contributions of heredity and environment to adult size and shape must therefore always specify the circumstances with some exactness. A biologically permissible statement (provided all the evidence is really available), is, for example: ‘Eighty-five per cent of the variance of height in the population of young adults growing up in middle class homes in a London suburb in the 1980s is due to genetical factors’. In a population growing up under famine conditions the percentage of variance due to genetical factors would be expected to be less. A particularly lucid discussion of these points may be found in Thoday (1965).

The period of European exploration in the fifteenth and sixteenth centuries resulted in the establishment of colonies abroad. Migrants from Europe were widely distributed over the globe and formed permanent populations which have persisted in the Americas, Australia, New Zealand, and parts of Africa. Though the last large-scale European migrations were those to North and South America in the early decades of this century, some migration still continues, particularly to Australia, New Zealand, and Canada.

In this chapter we shall attempt to consider populations that are comprised almost entirely of European, rather than of mixed descent. However, such distinctions are sometimes not stated in reports on child growth, especially those from Latin America.

The growth studies

The populations selected for analysis are listed in Table 3. From Canada we have new data only on French-speaking children: two longitudinal studies, one in Montreal and one in the city of Trois Rivieres. The latter study primarily involves physical performance and includes separate analyses of a rural area as well as the city itself. Since our last edition the United States National Center for Health Statistics (NCHS) has published data from two National Health and Nutrition Examination Surveys: NHANES I, collected from 1971–4, and NHANES II, collected from 1976–80. We will use only the latter. This publication (Najjar & Rowland, 1987) gives means for the entire sample which includes approximately 15 percent Afro-Americans. Since we wanted to separate the data on Euro-Americans from that on Afro-Americans, we have had the NCHS data tapes analyzed by ethnic group through the courtesy of the University of Texas Houston School of Public Health.

In this chapter we are concerned with a third major group of peoples, here designated ‘Asiatics’. We employ this name to refer to the groups of peoples originating in the Far East: we include the classical Mongols of Mongolia, Tibet and northern China; the Arctic Eskimos; the American Indians or Amerindians who, although inhabitants of the Americas, originally migrated from Asia (MacNeish, 1971); and the Indonesian- Malays. The last group probably has had a varying amount of admixture with Indo-Mediterranean and African peoples (Montagu, 1960). Japanese, Chinese, Filipinos and Thais are some of the populations designated as Indonesian-Malay. There is great diversity in adult Asiatic populations, and this is reflected in the growth of the children.

The growth studies

A description of the recent growth studies we have selected is given in Table 6. There are two studies on growth in Tibetan children in Nepal (Beall, 1981; Pawson, 1977). We have one new study only on Alaskan Eskimos; this is on a small group on St Lawrence Island in the Bering Sea (Johnston et al., 1982).

There are a number of new studies on Amerindian and mestizo populations; notable among them are the various high-altitude projects in the Andes. Mueller and his colleagues have reported on the Multinational Andean Genetic and Health Program which consists of multidisciplinary studies of the Aymara in Chile and Bolivia (Mueller et al., 1978a,b; 1980; 1981). Stinson (1980; unpubl.) also has been studying the Aymara in the Lake Titicaca region outside La Paz and, with Frisancho, the Quechua in highland and lowland towns in Peru (Stinson & Frisancho, 1978).

A considerable proportion of the mean differences in body size among the populations we have been examining is due to the effects of environmental conditions. Some of the differences between individuals within populations are also due to differences in environment. In the better-off populations of industrialized countries these latter differences are relatively small, while in the developing countries the gap between well-off and poor is greater. A child may receive numerous insults during growth and yet survive, but bodily adaptations for survival are made which may result in a slower tempo of growth and a smaller body size. If a whole population receives similar insults, such as a diet low in calories or protein, a small mean adult size results. If environmental conditions improve, the size both of children and adults increases. ‘Human height’ wrote Louis-Rene Villermé, the founder of public health in France, ‘becomes greater and growth takes place more rapidly, other things being equal, in proportion as the country is richer, comfort more general, houses, clothes and nourishment better and labour, fatigue and privation during infancy and youth less; in other words, the circumstances which accompany poverty delay the age at which complete stature is reached and stunt adult height’ (1829, cited in Tanner, 1981, p. 162).

There are many environmental factors which affect growth, and which combine in various proportions to constitute the environment of poverty; but in the final analysis most of them hinge upon the level of nutrition in conjunction with the prevalence of childhood infection.