What is the cost of living in the Papua New Guinea highlands? An answer is sought using a time and energy accounting approach. The subsistence regime of Wola-speaking highlanders, the subjects of this investigation, comprises three components. The principal one is horticulture: people clearing gardens from forest and grassland, with tuberous crops predominating, notably sweet potato. The second component comprises animal rearing, notably of domestic pigs. The third, and least important, is hunting and gathering for food in the forest. The calculated returns on investments in these subsistence domains vary considerably. Gardens return in their crops between ten and fifteen times the energy expended in cultivation. Pigs may also give a good return, of four to five times the energy invested in rearing them, if slaughtered when adult, but people regularly keep animals for years and may incur negative energy returns on their labour investments. This relates to the high cultural premium put on pigs. Foraging for food is also energetically costly, the Wola expending four times more energy on these activities than they gain in return from the food they secure. This analysis of energy gains and losses challenges the relative notion of affluence as applied to foragers, by reviewing it in the comparative context of subsistence horticulture.

Reproductive characteristics at high altitude are described based on the reproductive histories of 720 Aymara women, collected in 1998 and 1999 in a group of twelve peasant communities at a mean altitude of 4000 m in the Bolivian Altiplano. The reproductive pattern is shaped by a late onset of childbearing, associated with a rather short reproductive span and large birth intervals. Environmental conditions could explain the particularly late age at menarche of rural girls compared with their urban counterparts, whereas the age at first birth is likely to be under cultural control. The short reproductive span appears to result from a large mean interval between last birth and menopause, which is essentially determined by cultural decisions. The birth intervals, which are longer than in many traditional societies, could be the result of a slower restoration of postpartum fecundability induced by the hard way of life inherent in the Altiplano (including poor sanitary and nutritional conditions and high workload), perhaps aggravated by hypoxia. However, a secular trend in fertility is perceptible, towards earlier menarche, earlier age at first birth, increasing reproductive span and a slight increase in live births and surviving offspring, which is probably the result of a slow improvement in living conditions. The existence of birth control on the one hand, and a total fertility rate averaging six live births among the couples who do not practise contraception on the other, are other arguments against the hypothesis of a low natural fecundity in these Aymara groups.

This study examines fertility decline that is larger than expected on the basis of recorded increases in contraceptive prevalence in Ghana. The primary sources of data are three Demographic and Health Surveys (DHS) conducted in the country in 1988, 1993 and 1998. First, the trend in fertility and contraceptive prevalence in Ghana is considered and compared with the trend that would be expected on the basis of prior research. Next, an attempt is made to uncover the explanation behind this unexpected trend. Measures of the quality of the survey data are looked at, as well as trends in the proximate determinants of fertility: contraceptive use, marriage and sexual activity, postpartum insusceptibility and induced abortion. Finally, evidence is presented that couples adjust their coital frequency in accordance with their fertility preferences, behaviour that would influence fertility rates but would not be captured by conventional measures of the proximate determinants of fertility.

African men play important roles in the decisions about family life, including fertility and family planning. However, fertility and family planning research and programmes have ignored their roles in the past, focusing only on women’s behaviours. Since the 1994 International Conference on Population and Development (ICPD), interest in men’s involvement in reproductive health has increased. Unfortunately, data on their knowledge and use of contraception are generally scanty. This paper examines knowledge and use of contraception among ever-married men in Nigeria. A total of 1451 ever-married men aged 18–55 were interviewed in Imo and Ondo States, Nigeria. The findings reveal that men’s level of contraceptive knowledge is high in the study areas. About 90% knew at least one method of family planning. Furthermore, the level of contraceptive use among married men is such that men could participate in family planning activities if there were adequate programmes to involve them. Men in the sample areas were found not only to support their spouses’ use of contraceptives, but were actually using condoms to delay or prevent pregnancy. Age, education, place of residence, number of living children and being counselled for family planning were identified as key factors determining contraceptive knowledge and use among married men in the study areas. To ensure increased participation of men in family planning, programmes must be designed to educate them on the need for family size limitation and involve them in service delivery, even if only to their male counterparts.

The present study involved analyses of a Caucasian American sample (n=949) and a Japanese American sample (n=400) for factors supporting Genetic Similarity Theory (GST). The analyses found no evidence for the presence of genetic similarity between spouses in either sample for the blood group analyses of nine loci. All results indicated random mating for blood group genes. The results did not provide consistent substantial support to show that spousal similarity is correlated with the degree of genetic component of a trait for a set of seventeen individual differences variables, with only the Caucasian sample yielding significant correlations for this analysis. A third analysis examining the correlation between presence of spousal genetic similarity and spousal similarity on observable traits was not performed because spousal genetic similarity was not observed in either sample. The overall implication of the study is that GST is not supported as an explanation for spousal similarity in humans.

This paper examines determinants of one aspect of sexual behaviour – coital frequency – among 2188 married women in the Central African Republic using a secondary analysis of data from the Demographic and Health Survey of 1994–95. Female genital cutting (or circumcision) is practised in the Central African Republic and self-reported circumcision status was included in the questionnaire enabling it to be examined as a possible determinant of coital frequency. Multiple logistic regression was used to find a subset of factors independently associated with coital frequency. Decreased coital frequency was found in those who had longer duration of marriage, those who were not the most recent wife in a polygamous marriage and those who had more surviving children. Coital frequency was higher in more educated women and those not contracepting because they wanted to get pregnant. After adjusting for confounders no association between female genital cutting and coital frequency was found. The extent to which women can control coital frequency in this culture is not known and fertility desires may override any negative effects of circumcision on sexual pleasure. It was therefore not possible to draw conclusions about how female genital cutting affects a woman’s desire for sexual intercourse and consequently there is a need to develop research methods further to investigate this question.

In this work, the evolution of demographic and health patterns in a Basque rural population from Spain is analysed, as they relate to progress in demographic and epidemiological transition. For this purpose, parochial record data on 13,298 births and 9215 deaths, registered during the 19th and 20th centuries (1800–1990), were examined. The study area is a rural community called Lanciego, which is located at the southern end of the Rioja Alavesa area (Alava Province, Basque Country). In Lanciego, demographic transition began in the final decade of the 19th century, when a definite, irreversible trend began towards a reduction in mortality. The decrease in the birth rate came later than that in the death rate, and did not start until the 1930s. The post-transitional stage seemed to be reached in the 1970s, when the birth and death rates showed values below 20 per 1000. Other characteristics observed for the post-transitional stage in Lanciego are: (i) very low rates of infant mortality achieved at the expense of effective control of exogenous mortality; (ii) the mortality curve by ages changes from a U-shape (typical of populations with a high infant mortality rate and low life expectancy at birth) to a J-shape more characteristic of modern societies where longevity and life expectancy are considerably higher; (iii) a certain level of over-mortality among women in the senior age group (>65); and (iv) a significant proportion of mortality in recent times (1970–90) resulting from cardiovascular diseases and malignant neoplasms (post-transition causes). This last point is in contrast with observations from the first four decades of the 20th century, when infectious diseases and respiratory ailments were determining factors in mortality among this population. The data provided by the study of the variation over time in demographic and health patterns indicate that reducing the risk of mortality is one of the most important preconditions for fertility decline.