Population variation in children's behavioral symptomatology.

Previous anthropological studies identified significant interpopulation consistencies in the frequency and symptoms of adult depression, anxiety, and schizophrenia. Tests of the degree of variation of such behavioral phenomena across contemporary populations are significant for the study of human evolution because universality or near universality suggests specific evolved aspects of human behavior. The aim of this research was to provide a preliminary test of whether cross-cultural consistencies in symptomatology associated with some psychiatric conditions are observable in children as they are in adults. We tested for interpopulation variation in degrees (intensity and frequency) of anxiety, depression, withdrawal, and somatization symptomatology in normal samples of children. Psychometric ratings scales allowed assessment of characteristic symptomatology of each child in the different contexts of home and school. The study populations comprised 1,208 6-11-year-old children from the Paisa community in Antioquia, Colombia, and African-American, Euro-American, and Hispanic children in the United States. We found interpopulation consistencies in some aspects of child behavioral symptomatology, especially depression and withdrawal. Mean degrees of symptomatology and percentages of children with clinically significant levels of symptomatology were consistent for both across populations, in home and school contexts, and for both girls and boys. Anxiety and somatization displayed more cross-cultural variability in expression. These patterns are in accordance with current understandings of cross-cultural variability and universals of adult psychiatric symptomatology.

Structure of family planning in Samoa.

Increasing family planning acceptance and efficacy is considered a key public health issue in many Pacific island nations. To assess the structure of family planning acceptance in Samoa, structured interviews were conducted with 155 reproductive age women from seven villages in both rural and urban settings. The survey data show accord with returns on contraceptive use from Samoan clinics, and demonstrate that awareness and use of contraception have increased markedly in the previous decade but desired family size remains high in younger women. A notable feature of the Samoan women's contraceptive experience is the lack of diversity of reported contraceptive behaviours and attitudes based on age, urban versus rural residence, and education.

Perceptions of body size in Pacific Islanders.

OBJECTIVE: To assess attitudes to body size and obesity in Samoans, a Pacific island group characterised by very high levels of obesity and traditionally strong positive cultural views of large bodies. DESIGN: Cross sectional study of Samoan adults in Samoa and New Zealand. SUBJECTS: 84 female and 77 male Samoans in Samoa and 41 female and 24 male Samoans in Auckland, New Zealand, aged 25-55 y. MEASUREMENT: Body mass index (BMI), standardised survey questionnaires of perceptions of bodyweight and health, diet and exercise, and perception of body sizes on a continuous scale. RESULTS: Although Samoans in both countries display high population levels of obesity, ideal body sizes are slim and body dissatisfaction and attempted weight losses were apparent. However, women and men above normal weight did not characteristically perceive themselves as obese, were as positive about their body size, weight and health, and obese women were no more likely to be attempting to lose weight than their slimmer peers. CONCLUSIONS: The traditional Samoan veneration of large bodies is not apparent as ideal body sizes are slim. An important difference in values with Western industrialised societies is the absence of a strongly negative view of obesity.

Patterns of colonisation and the "thrifty" genotype in Pacific prehistory.

The seemingly distinctive markers of Polynesian biology - serologic, molecular, anatomical, and developmental - have been argued to have emerged from the special circumstances of colonisation and early settlement of the region. Models point to the microevolutionary impact of mortality selection while voyaging, small founding group size forcing bottlenecking, and subsequent relative isolation of groups introducing heterogeneity through genetic drift within Polynesia. These ideas have drawn on a melange of ideas about the colonising experience to construct evolutionary narratives, including that of the "thrifty" genotype in Polynesia. The substantial problem is that there previously has been no independent theory of colonisation and inter-island contact for the region. We critically examine which microevolutionary forces would have impacted prehistoric Polynesians in terms of an independent navigational theory of colonisation, and map out the expected biological/ evolutionary sequelae. This theory suggests that Remote Oceania was settled by directed return voyages, that the tempo of population expansion was probably rapid, that voyaging continued after settlement, that whereas episodes of colonisation were directed to safety, subsequent inter-group voyages followed the pattern of mutual inter-island accessibility. The implication is that mortality selection would not have been the predominant force shaping the Polynesian genotype; the development of survival sailing strategies were designed to remove these very risks. This makes it unlikely that the specific experience of Polynesian colonisation would promote an efficient insulin mechanism, and so explain, for example, the high incidence of Type II diabetes mellitus in contemporary Polynesian groups.

Sex ratios at birth in Micronesia: reply to James.

PIP: In response to comments of William H. James on the authors' articles, it is stated that Micronesian populations are now and have been in the past characteristically highly masculinized at birth (i.e., secondary sex ratios [SSR] of over 108-110). It is fascinating to examine how this finding may reflect microevolutionary change in this island setting. Aspects of reproductive behavior in Micronesia were examined for clues to proximate/remote mechanisms that may promote this pattern of male versus female births. One of the most singular defining features of the reproductive pattern of these groups is high coital rates, maintained against age and marriage duration. It is argued that SSR patterns in Micronesia are a corollary of the unique biobehavioral reproductive features of these island groups, which includes high coital rates. Professor James' concerns relate to 2 considerations: 1) the statistical aspect of results from small scale populations, and 2) the veracity and reliability of results from ethnographic research. Methodologies employed by modern ethnographers entail extensive and intensive cross-checking, multiple verification, and repeated re-evaluation of information collected from a large number of independent sources. In the Butaritari case, conclusions are drawn from several very different but consistent lines of evidence that show coital rates are maintained with age and marriage duration in this group: ethnographic data showing the marriage relationship maintains a highly sexualized environment, demographic data showing no effective reduction in fertility through the first 2 decades of marriage. In the case of the sex ratios, almost all births in these populations over the last century have been covered, and sample sizes in the thousands are available. These are acceptable for use of chi-square and sufficient to make inferences about variations in sex ratios by age group as they relate to coital activity.^ieng

Age and infertility in a micronesian atoll population.

The relationship between female age and infertility is examined using a single-island Micronesian population case. Demographic data, derived primarily from reproductive history interviews, show that a significant age-associated decline in marital reproductive performance is absent before women reach their late thirties in this population but a substantial decline is present once women reach their forties. Ethnographic data support the demographic inference that couples are maintaining relatively high levels of conjugal coital activity with both advancing female age and increasing marital duration. Thus coital activity levels appear to be an important factor in the maintenance of fertility in this group before the mid-thirties but decreases in fecundability after this age are due primarily to reductions in fecundity, not to declines in coital activity. The description of the Butaritari case lends support to Underwood's (1990) suggestion that a "Micronesian pattern" of reproductive performance may exist for the region's atoll-based populations and underscores the promise of further investigations of these special cases in the fields of demography and reproductive ecology.

PIP: The aim of this study of infertility was to describe demographic patterns of infertility by age and their link with age-associated behavior changes, such as coital activity, on the Butaritari Atoll north of Tungaru in the Republic of Kiribati. The population is relatively circumscribed on this high-population-density island; there were high rates of nuptiality, minimal premarital exposure to pregnancy risk, low contraceptive usage, and an absence of sexually transmitted diseases that cause infertility. The population in 1990 was 3800, of which almost 50% were aged 15 years. Fertility was high, at a mean of 4.5 births for ever married women (N=791) and a completed fertility of 7.14 for ever married postmenopausal women. Almost all men and women marry. Primary infertility levels were only 1.29% of ever married postmenopausal women (N=231). Data on reproductive histories were collected from 87.1% (N=203) of all women aged 15 years in the village in 1990/91 and supplemented with other archival records. A subsample of 34 women were interviewed for a detailed analysis of life course changes in reproductive and sexual behavior. Census data from 1990 were also collected and checked against vital registration records. The following measures were examined: infertility in relation to marriage duration, current reproductive status of women in relation to age, infertility in relation to parity, infertility in relation to age, pregnancy failure in relation to age, and ethnographic factors. The findings indicated that infertility rarely occurred before the late 30s because of the low levels of subfecundity, no age variation in breast feeding patterns, no significant increase in reported fetal death rates before the 40s, and sustained coital frequency with increasing marriage duration. Coital frequency declined after the age of 40 years, as did fecundity. The coital patterns were found to be similar to the Micronesian region; women produce as many children at later ages as they do at earlier ages.

Sex ratios at birth in a Micronesian Atoll population.

The recent suggestion that typically masculinized sex ratios at birth in Micronesian populations may be related to a distinct "Micronesian pattern" of life-course coital behavior is applied to data on the sex ratio of livebirths on Butaritari Atoll in Kiribati. The data show that sex ratios on Butaritari are highly masculinized and do not vary significantly with changes in maternal age. However, there is a discernible relationship between the length of closed intervals preceding male and female births. The lack of age-related change in sex ratios in the Butaritari sample is inconsistent with ethnographic data regarding levels of marital coital activity in relation to increasing age and marriage duration. The Butaritari sex ratio data is argued to support the suggestion of a "Micronesian pattern," although it is posed that further tests of this association are required.

PIP: This paper tests Underwood's proposition that there is a distinctive Micronesian pattern of continuing high levels of sexual activity regardless of age or marital duration. Data were obtained on secondary sex ratios (SSR) at birth by parental age, birth order, and birth interval from 201 Butaritari women in Kiribati in 1990; there were 631 births of known sex. The SSRs were considered reliable and in line with other SSR data in the Micronesia-Polynesia region. Reproductive histories of this population revealed a sex ratio at birth of 111.0. The SSR for women aged 30 years was 117.7; and for women aged 30 years, 107.8. Differences in SSR were not statistically significant for either paternal or maternal age differences. The SSR for fathers aged 30 years was 112.0 and for fathers aged 30 years was 104.8. The pattern of declining SSR with increased parity was not found: the highest SSRs were among middle order births. As preceding birth interval increased, there was a trend toward increasing femininity. There was a significant difference between mean birth intervals of 28.04 months and 31.48 months for male births preceding female births. Significant differences were also found between birth intervals of 2 years and 2 or more years. The evidence of masculinized sex ratios and slight increases with age led to the inference that coital activity is being maintained with advancing maternal age and with increasing marital duration. The significant difference in SSRs with increasing birth intervals and more female births supports the proposition that more frequent acts of coitus are related to earlier conceptions and shorter birth intervals, lower sex ratios are related to longer birth intervals. The frequency of coital activity with age was also evidenced in studies of the Chamorros of Guam by Underwood. There was also the suggestion that a pronounced masculine sex ratio might be the norm for Polynesian and Micronesian regions and not just atoll-based groups.

Sexually-transmitted disease risk in a Micronesian atoll population.

The potential health threat of AIDS to the native island-based populations in the Pacific is now widely appreciated by those working in the public-health sector throughout the region. Although several countries in the region are yet to identify any cases of AIDS or HIV seropositivity, there is reason to suspect that heterosexual contact may emerge as a predominant mode of spread of HIV infection into native Pacific island populations. Sexual networks and their relationship to potentially 'risky behaviours' are described for a single native Micronesian atoll community on the basis of ethnographic observation and interviewing. This description is combined with the investigation of historic-demographic dimensions of the epidemiology of sexually-transmitted diseases in the same population to draw some conclusions about the opportunities for HIV transmission and acquisition among the sexually-active portions of this community. Although sexually-transmitted diseases have not had an appreciable epidemiological or demographic impact on the population in the past, the sexual networks within the community and beyond provide ample opportunity for the introduction and spread of sexually transmitted diseases, including HIV and its sequel AIDS.

PIP: Sexually transmitted diseases (STDs) contributed to reductions in fertility and population size in many Micronesian islands between the late 1800s and early 1900s. This paper explores the potential health threat of AIDS to an indigenous village population of 1250 on the Butaritari Atoll, Kiribati. Study results are based upon observations, surveys, and interviews exclusively with women in the community over 12 months in 1990-91. This population is of Catholic faith and high fertility, with a low biomedical contraceptive acceptance rate and near universal marriage by age 25. Marriage in this culture may be either socially formalized and permanent or consist solely of temporary relations between married men and nonmarried women while men are employed on other islands away from wives. Generally, those who cohabit and have sexual relations are considered married. Little premarital sexual activity takes place in this community; women are expected to be virgins at marriage. Men, however, are encouraged to gain premarital sexual experience. Since young men only infrequently succeed in having sex prior to marriage, most sexual activity occurs within marriage. Women are passive in all aspects of the sexual relationship are dare to discourage their spouses' sexual advances only during menstruation, in advanced pregnancy, after birth, and when they are ill. Female marital infidelity is not tolerated, though married men are known to seek attention from the limited pool of nonmarried women in the population. At most, men may secure the attention of five such women over the course of their lives. Anal sex is not practiced within heterosexual relationships and homosexuality is very rare and not tolerated. Despite these relatively conservative sexual norms, HIV threatens to enter and spread within this community through heterosexual intercourse. Men from Kiribati work off-island on foreign ships for months at a time. While away, they have been known to have sex with foreign prostitutes and may contract STDs. On vacation and when contracts expire, these men return to the island to recommence their usual sexual relations. Both married women and the small percentage of unmarried sexually available women may be infected by these men. HIV may then spread among other married couples and single individuals in the community. The frequent practice by women of inserting vaginal agents and cauterizing their genitals to dry and tighten the vagina also increases the potential for mucosal tearing and subsequent HIV infections. In closing, the reader is cautioned to not infer that observations from this community are universally applicable within Micronesia; Kiribati historically has suffered less than other regional islands from STDs.

Modeling the prehistoric Maori population.

Skeletal and comparative evidence of mortality is combined with fertility estimates for the precontact Maori population of New Zealand to determine the implied rate of precontact population growth. This rate is found to be too low to populate New Zealand within the time constraints of its prehistoric sequence, the probable founding population size, and the probable population size at contact. Rates of growth necessary to populate New Zealand within the accepted time span are calculated. The differences between this minimum necessary rate and the skeletally derived rate are too large to result solely from inadequacies in the primary data. Four alternative explanations of this conundrum are proposed: 1) skeletal evidence of precontact mortality is highly inaccurate; 2) skeletal evidence of fertility is severely underestimating actual levels; 3) there was very rapid population growth in the earliest part of the sequence up to 1150 A.D., from which no skeletal evidence currently is available; or 4) the prehistoric sequence of New Zealand may have been longer than the generally accepted 1,000-1,200 years. These alternatives are examined, and a combination of the last two is found to be the most probable. The implications of this model for New Zealand prehistory and Oceanic paleodemography are discussed.