This study reports an ecologic analysis of the relationship between mean birth weight (MBW) and nutritional, medical and social variables, using 1982 data for 47 prefectures in Japan.

Correlation analysis showed that variables that correlated significantly with MBW were mean temperature (r=0·63), total calorie intake (r=0·56), and body mass index of women (r=0·60). It is concluded that the MBW level in a given community represents the long and short term nutritional condition of mothers, and that the level may follow Bergman’s law: ‘In the same species, the body size of an animal increases along with latitude; that is, the lower the temperature, the larger the body size’.

This paper presents information on the opportunity for genetic drift in La Alpujarra, a rural population of the Spanish Mediterranean. This region is characterized by its historical isolation. The analyses were based on a survey of 45% of the population. The Effective Population Size (NE=1986), the Effective Migration Rate (ME=12.4) and the Coefficient of Breeding Isolation (CBI=246.2) of Lasker & Kaplan (1964) were calculated. The value of the latter index indicates that genetic drift in the Alpujarrenian population is negligible at present because of the cessation of reproductive isolation due to the development of communication networks.

Homosexual men have a higher mean birth order than do heterosexual men, primarily because they have a greater number of older brothers. The purpose of this study was to determine whether the same difference occurs in homosexual vs heterosexual women. The probands were 964 homosexual and heterosexual, male and female volunteers, from whom birth order data were collected with self-administered questionnaires. The homosexual men had more older brothers than the heterosexual men, but they did not have more older sisters, younger brothers, or younger sisters. The homosexual women did not differ from the heterosexual women with regard to any class of sibling. These results are consistent with the hypothesis that the high birth order of homosexual men reflects the progressive immunization of certain mothers to H-Y antigen by succeeding male fetuses, and the increasing effects of H-Y antibodies on sexual differentiation of the brain in succeeding male fetuses.

This paper calculates the mean duration of the postpartum amenorrhoea (PPA) and examines its demographic, and socioeconomic correlates in rural north India, using data collected through 'retrospective' (last but one child) as well as 'current status' (last child) reporting of the duration of PPA.

The mean duration of PPA was higher in the current status than in the retrospective data;n the difference being statistically significant. However, for the same mothers who gave PPA information in both the data sets, the difference in mean duration of PPA was not statistically significant. The correlates were identical in both the data sets. The current status data were more complete in terms of the coverage, and perhaps less distorted by reporting errors caused by recall lapse.

A positive relationship of the mean duration of PPA was found with longer breast-feeding, higher parity and age of mother at the birth of the child, and the survival status of the child. An inverse relationship was found with higher education of a woman, higher education of her husband and higher socioeconomic status of her household, these variables possibly acting as proxies for women's better nutritional status.

Human water contact patterns were studied in two resettlement communities at the Oyan Reservoir in south-west Nigeria in all four seasons in 1991 and 1992. Water contact was most intensive in the afternoon and in the hot dry season, but different types of activities exhibited different daily and seasonal patterns. Both communities were highly endemic for urinary schistosomiasis. However, knowledge regarding schistosomiasis transmission was very limited and the infection was, in spite of a very high frequency of blood in the urine, not considered a major public health problem. Most water contacts were of either a recreational (swimming, bathing) or economic (fishing) nature, and age- and sex-related patterns were evident. The overall level of exposure peaked in the 10–14 years age group but water contact of an economic nature peaked in the 20–39 years age group. Females had generally more water contact than males.

In order to examine the prevalence of HIV infection and associated risk factors amongst Spanish female prostitutes a multicentre (n=22) cross-sectional study was conducted between November 1989 and January 1991. Data collected included socioeconomic characteristics, sexual behaviour and health status together with blood samples. A total of 1633 prostitutes were recruited into the study. Of these, 1433 (87.8%) consented to blood samples being taken and 180 (12.6%) were HIV positive. HIV seroprevalence was 54.7% for intravenous drug users (IVDUs) versus 3.7% for non-IVDUs. Previous imprisonment, hepatitis B and a partner who was an IVDU were significant predictors of HIV infection according to multivariate logistic regression models.

Eight hundred and eighty-seven students from two major universities in Delhi, India, were surveyed, using a self-administered questionnaire, about their sexual knowledge, attitudes and behaviour. The data show that female students seem to be rejecting traditional Indian repressive sexual standards of premarital and non-procreative sex and the gender differences are beginning to narrow. Despite their sexual awareness, the students were highly ignorant of the facts of life. Being male and married did not make them more knowledgeable.

Data were obtained on surnames of the parents and places of birth of the parents and grandparents of children in Siena, Italy. Isonymy and total inbreeding coefficient, and their random and non-random components, are 0·005, 0·00125, 0·00019 and 0·00106, respectively. Isonymy and inbreeding figures are similar to those of other medium-sized Italian towns, while higher values have been reported for Italian villages and Italian ethnic minorities. City endogamy, and endogamy of Contrada for grandparents have the same values (44·1 and 44·8%, respectively), but for parents, endogamy of Contrada is lower than city endogamy (15·2 and 33·4%, respectively). The difference between the extent of Contrada endogamy expected at random and observed in the parents' generation does not seem to affect the genetic structure of the present population. However, the bulk of marriage migration (more than 70%) is short range, with people coming from Tuscany. There is no statistical difference in marital migration between males and females.

The effects of breast-feeding and supplementation practices on recent diarrhoea occurrence and stunted growth are modelled using logistic regression techniques. Data from the Demographic and Health Survey of Bolivia, 1989, show that, among children aged 3-36 months at the date of interview, the benefits of breast-feeding to child health were most pronounced among children living in rural poverty. Reduced breast-feeding among these children increased the likelihood of diarrhoea and stunted growth. In addition, the introduction of solid foods to currently lactating infants negatively influenced child health.

Family planning programmes in Tanzania date back to the 1950s. By the early 1990s, however, only 5-10% of women of childbearing age used contraceptives in the country. Low contraceptive prevalence in Tanzania is reportedly attributable to men's opposition to family planning. This paper employs focus groups to explore the role of Tanzanian men in family planning. More specifically, it presents a rural-urban comparison of the attitudes of men in Mbeya region, Tanzania, to family size preference, sex composition, partners' communication on family planning matters and contraceptive behaviour. Findings indicate that men express positive attitudes towards fertility-regulating methods. There is, moreover, little rural-urban variation in male attitudes towards family planning in the study area. Possible reasons for this normative convergence (including structural similarities and rural–urban migration between the two communities) are discussed.

Consanguineous marriages are strongly preferred in much of West and South Asia. This paper examines the prevalence and sociodemographic correlates of consanguineous unions in Pakistan using local and national data. Information from 1011 ever-married women living in four multi-ethnic and multi-lingual squatter settlements of Karachi, the main commercial centre of the country, are compared with data from the national 1990/91 Pakistan Demographic and Health Survey (PDHS), based on information provided by 6611 women. Both sets of results indicate that approximately 60% of marriages were consanguineous, over 80% of which were between first cousins. The mean coefficients of inbreeding (F) in the present generation were 0·0316 and 0·0331 for the Karachi and PDHS data respectively. In both surveys the prevalence of consanguineous unions appeared to be unchanged over the past three to four decades. Consanguineous unions were more common among women who were illiterate or had only primary level education, were first or second generation migrants from rural areas of Pakistan or, in the PDHS, lived in rural areas, and whose parents were also consanguineously married.

The author's theory that among adults men have a higher mean IQ than women has been critized by Mackintosh. His criticisms are examined and found wanting. New evidence is adduced that men obtain higher means than women on Raven's Progressive Matrices.

In collaboration with the National Committee for Population and Family Planning, a study was conducted in 1994 in two Vietnamese communes to provide community level information on women's reproductive health and behaviours. A survey of 504 rural and 523 urban women collected five-year histories of reproduction, contraception, abortion and symptoms of Reproductive Tract Infections (RTI). This analysis focuses on the relationships between women's individual characteristics, use of family planning and abortion, and reported RTI symptoms. The findings reveal that IUDs do not raise women's likelihood of experiencing RTI symptoms in either commune. A recent abortion, however, strongly increases women's likelihood of having RTI symptoms in the rural commune, while low socio-economic status is associated with RTI symptoms in the urban commune.

Do males and females differ in general intelligence? Lynn (1994, 1998) and I (Mackintosh, 1996) agree that the answer to this question must depend on the answer to two prior questions: what is the definition of general intelligence, and what tests best measure it? Our disagreement arises partly from different answers to these prior questions, but also from differences in our reading of some not wholly consistent evidence. What answers might one give to these prior questions? They are not independent, for a possible (severely operational) definition of general intelligence is that it is a person's score on one particular IQ test battery. Let us start with that simple possibility.

The eleventh Annual Workshop of the Biosocial Society will be held on Friday 8 May 1998 from 10.00 to 16.00 hours at the Department of Biological Anthropology, University of Cambridge, Downing Street, Cambridge.

Amankwaa (1996) gives data on infant mortality in monogamous and polygynous families. However he does not categorise his data by sex. This is important because one might expect infant mortality to vary by sex; moreover the offspring sex ratios of polygynous and monogamous women reportedly differ.

James questions the validity of the very tentative statement made in the final sentence of our paper. Our claim concerned the proportion of twins in Britain in the 1990s that might have arisen through subfertility treatment and was linked to the s uggestion that the natural twinning rate might still be in decline. If this were true, we, like James, would regard that prospect with concern.

The Anjangmui dialect group of the Kombio in Papua New Guinea has experienced a rapid increase in rural-urban migration since European contact commenced in the 1930s. Population ecology analyses of birth and migration histories for 240 Anjangmui women showed a higher total marital fertility rate in the cohort born in 1940-59 than that born in 1920-39. A decline in the age at menarche for nutritional reasons, and reduction in the birth interval for behavioural reasons, may explain the fertility difference between cohorts. Comparison of age-specific marital fertility rates between migrants in urban areas and non-migrants in rural areas revealed higher rates among migrants in the 15-19 and 20-24 year age groups, but lower rates in the 25-29 year or older age groups; the total marital fertility rate for migrants was lower than that for non-migrants. The differences may be attributable to the different influences of birth control practices on fertility reduction between the migrants in urban areas and non-migrants in rural areas. It is suggested that rural-urban migration in the Anjangmui during the post-contact period has had the effect of reducing fertility in the population as a whole.

From 1971 to 1984, the Israeli Defence Forces administered two tests unaltered that qualify as IQ tests. These were the Matrices and the Instructions tests. The former is an adaptation of Raven's Progressive Matrices, similar to the original in that there are clusters with progressive difficulty and an escalation of difficulty throughout the test. The raw score range is from 4 to 35. The Instructions test is adapted from the old US Army Alpha Instructions Test and is described as an Otis-type verbal test. It includes 21 open-ended instructions. Typical items: write the last letter of the word which is the opposite of black; write the third letter of the largest word among the following four words; find the word beginning and ending with the same letter and write that letter. There are similar questions using numbers rather than letters. Both tests are timed, and most subjects do not complete either. There is no penalty for wrong answers (Col. Moshe Even-Chen, personal communication, 14 March 1990; Gal, 1986, pp. 79 and 95; Judy Goldenberg, personal communications, 4 March 1991 and 25 April 1993).