Paul T. Baker

Modernization, migration and obesity among Samoan adults

Modernization and migration have biological as well as social effects on people. In this study, 2657 Samoan adults from Western Samoa, American Samoa and Hawaii were surveyed in an attempt to examine the relationships between modernization, migration and obesity. The Samoan men showed an increase in the frequency of obesity with increasing modernity of residence or occupation. While the women in American Samoa had the highest frequency of obesity of any subsample, Samoan women also demonstrated a pattern of higher adiposity in more modern jobs. Young women tended to show a negative relationship between obesity frequency and education, with college-educated women having the lowest average levels of adiposity. Time since migration to Hawaii was not found to exert a major effect on frequency of obesity.

Caloric requirements of human populations: A model

Currently available models used for predicting human caloric requirements do not reflect the great variability in activity patterns observed among populations, and are insensitive to important anthropometric, demographic, and environmental variables. They are thus inadequate for application to many populations and problems of anthropological interest. We present a model for determining caloric requirements which more accurately accommodates the effects of variation in activity and in anthropometries on individual needs, and which predicts population requirements based on individual needs and demographic parameters. The model is tested on four populations (the Andean community of Nuñoa, Peru, the Dobe !Kung of Botswana, and two New Guinean villages) and is found to provide consistently better estimates of caloric requirements than are generated by the Food and Agriculture/World Health Organizations model. This model should be useful to anthropologists and human ecologists concerned with problems involving human energy consumption, such as the efficiency of subsistence strategies, optimum family composition, or certain consequences of increased labor migration or technological change.

Variation in lifestyle characteristics and catecholamine excretion rates among young Western Samoan men

Comparisons of 13 lifestyle characteristics and the rates of urinary catecholamine excretion during typical morning activity are examined among four groups of young Samoan men in Western Samoa. The groups include 28 manual laborers, 33 sedentary workers, and 31 college students from the urban area of Apia, and 31 rural agriculturalists. Associations between the lifestyle variables and catecholamine excretion rates are also investigated in the total sample (N = 123) using correlations and multiple stepwise regression techniques. Results of the lifestyle characteristic comparisons show that the villagers have greater life satisfaction, emotional stability, agreement with Samoan customs, and familial responsibility (P less than 0.05). The catecholamine comparisons show that the villagers have lower rates of epinephrine and norepinephrine excretion than any of the Apia groups (P less than 0.05 and P less than 0.005 respectively). The regressions indicate that diet, activity, day of specimen collection and the overall lifestyle and ecological differences between the village and Apia are associated with 25 and 31% of the variation in the rates of epinephrine and norepinephrine excretion respectively. These results suggest that both psychological and habitual behavioral differences contribute to the catecholamine variation of the men in this study, and that these differences are related to the degree of participation in Western lifestyles.

Calcium: unusual sources in the highland Peruvian diet.

A dietary survey conducted in the southern highlands of Peru revealed two important sources of dietary calcium not previously reported. Mineral and ash calcium ingested as a food spice, and along with coca, raises the calcium intake from the low figures recorded by standard nutritional surveys to a more substantial level.

Biological aspects of human migration: Migration and adaptation

Within the general framework of evolutionary and adaptation theory there are a number of general principles that will assist in the understanding of the biological effects of migration. 1st populations with relatively stable social and subsistence and which have been long resident in a given area have adapted in their biology population structure and sociocultural system to this area and its environment. All biological adaptive patterns have genetic bases; however some are fairly specific and easily identifiable from their phenotypic expression while others are more plastic or flexible and are expressed more broadly depending on environmental circumstances. Several hypotheses have been suggested to define further the biological effects of migration: 1) The more rapid and dramatic changes will produce greater stress as manifested by illness loss of biological fitness and declines in sociocultural integration than will gradual and minor changes. 2) Adults particularly the elderly will suffer more from environmental change than will children. This is based on the knowledge that some adaptations require development during the period of child and adolescent growth. 3) Effects of environmental change on health and state of adaptation will be most acute immediately after a move. Adjustments will occur as exposure to the new environment increases. There is some evidence to support each of these 3 hypotheses yet they are not quite at the level of general principles. This literature review looks at existing studies that consider the biological and adaptive attributes of migrants which are important for at least 2 reasons. 1st at the level of science and basic knowledge migrant people serve as ideal natural experiments in which the effects of environmental change on human populations can be investigated within the theoretical framework of adaptation. Secondly there are real risks to human health and biological fitness associated with the process of migration and these risks should be known and understood. This latter applied basis for studies of migrants is especially important now since present migration rates are greater than at any other time in the past.

Altitude, migration, and fertility in the Andes

In order to examine the relationship between hypoxia and reduced fertility of high Andean populations, a sample of 241 females living in the low-altitude Tambo Valley of Peru was studied. 63 of the subjects were born in the low-altitude valley, 121 were migrants from high altitudes, and 57 were migrants born in low altitudes. The rate of abortion was low among high-altitude subjects before they migrated, but became greater after migrating. It was found that the high-altitude populations had almost twice as long parity intervals than the low-altitude populations. Compared to migrants born at low altitudes, the high-altitude-born subjects who migrated to low altitudes had higher fertility rates. The results of the study are consistent with the hypothesis that high altitudes, through anoxia, have a lowering effect on fertility. Of the several possible explanations which might account for the increase in fertility of downward migrants on migration from high to low altitude (migration, socioeconomic factors, acculturation, seasonal male emigration from high altitude, and removal of hypoxia stress), altitude appears to be the most significant.

Modernization and catecholamine excretion of young Samoan adults

Urinary catecholamine excretion rates have been used as a cross-culturally valid measure of generalized stress. The purposes of this paper are to examine group differences in catecholamine excretion rates in three Samoan groups who differ in degree of modernization and to compare these findings to rates of norepinephrine and epinephrine excretion in other populations. In 1986-1987, 24-hr urine samples were collected from 18-37-year-old Samoans; 46 rural Western Samoan villagers, 53 American Samoans, and 49 Samoans residing in Honolulu. The results show that norepinephrine excretion is significantly higher in more modernized Samoan groups (P less than 0.05), while epinephrine excretion is not significantly different in the three groups. The higher norepinephrine excretion rate in the more modernized Samoan groups may be related to differences in relative work load associated with changes in body weight, work capacity, and work patterns which accompany modernization. Samoan epinephrine excretion rates are relatively high compared to the results of other population studies, while norepinephrine excretion in three Samoan samples ranged from among the lowest rates observed worldwide to among the highest.

The Raymond Pearl memorial lecture, 1996: The eternal triangle—genes, phenotype, and environment

Attempts to understand the causes for phenotypical differences in the biology and behavior of human populations have tended to focus alternatively on genetic, cultural, and natural environmental variables. The relative narrowness of focus in these studies often impedes the development of research design appropriate to the hypothesis and the process of reaching reasonable conclusions. Past research on native high‐altitude populations is used first to illustrate the deficiencies of research based on single variables and errors which can occur in conclusions about causal factors when potential genetic contributions are excluded. Analyses of blood pressure data from Samoan modernization studies are used to illustrate the complexity of determining causality in the development of a pathological condition. The need for better qualified cross‐cultural measures is emphasized. Am. J. Hum. Biol. 9:93–101

Environment, migration and health in Southern Peru

Abstract A health questionnaire was given to three populations of Peruvians: low-altitude sedentes, low-altitude migrants and high-altitude migrants, all of whom resided in the same low-altitude valley. Estimates of health were computed for each individual by summing the number of symptoms reported in the questionnaire. In general, male and female high-altitude migrants reported more symptoms than low-altitude sedentes. Female low-altitude migrants also reported more symptoms than did female sedentes, while there were virtually no differences between male low-altitude migrants and sedentes. Differences in numbers of days ill and the inability to work due to illness paralleled the differences in reported symptoms. It is suggested that the population differences are primarily the result of changes in the physical and cultural environments which are related to migration: high-altitude migrants being more affected than low-altitude migrants because of the greater degree of change they experience in migrating from high to low altitude. Specifically male high-altitude migrants reported significantly more gastrointestinal symptoms while both males and females reported significantly greater numbers of respiratory symptoms. Although the source of the former difference is unclear, it is felt that the increase in respiratory symptoms is a result of biological adaptations to high altitude which are no longer functional at low altitude.

THE BIOLOGY AND HEALTH OF ANDEAN MIGRANTS A CASE STUDY IN SOUTH COASTAL PERU

Migration always entails a change in social environment and adjustment to unfamiliar institutions and surroundings. Andean migration frequently also entails a major change in physical environment when high-altitude natives move to low altitude and experience an abrupt. and extreme change in environmental features such as oxygen pressure, temperature, and humidity, which vary with altitude. Both historical and contemporary sources indicate that natives of one altitude encounter significant physiological difficulties in adapting to vastly different elevations and this knowledge has concerned Andean administrators and governors since Incan times (Buskirk, 1976; Frisancho et al., 1973; Monge, 1948; Monge, 1963; Noble et al., 1974). At the present time, there is massive migration from high to low altitude in the Andes and the consequences for the migrants are not known. Indeed, as reported in the MAB 6 meeting in La Paz (UNESCO, 1975), this problem is viewed as a critical one in the Central Andes. Theories of biological adaptation and of social change predict deleterious sequelae of migration, at least temporarily, since migrants are in the process of adapting to a number of changed environmental features. For example, migrants may experience change in population density, population size, occupation, be newly introduced into cash economies and to western medical systems and experience changes in the physical environment. A further prediction is that the more changes a migrant undergoes, the greater the difficulty he has in adjusting. Therefore, migrants between altitudinal belts who experience all of these changes are expected to have greater difficulty in adapting than migrants within belts who do not experience the altitudinal change. However, a confounding