There are a number of reasons for anticipating that contact by women in developing country settings with modern maternal–child health (MCH) services will lead to increased use of family planning services. Indeed, the expectation of such a relationship underlies the integrated service delivery strategy that has been adopted on a more or less global basis. However, the available empirical evidence in support of this proposition is inconclusive. This study re-examines this issue in Morocco. Household survey data and data on the supply environment for health and family planning services gathered in 1992 are analysed in the study. A full-information maximum likelihood estimator is used to control for the possible endogeneity of health care and contraceptive choices. The findings indicate a substantial and apparently causal relationship between the intensity of MCH service use and subsequent contraceptive use. Policy simulations indicate that sizeable increases in contraceptive prevalence might be realized by increasing the coverage and intensity of use of MCH services.

A study has been made of the probabilities of marriage of females and males aged 15–49 (either as a whole or in 5-year age groups) in two Outer Hebridean islands, Harris and Barra. The results were compared with ages of marriage and with the frequencies of permanent celibacy. The marriages took place between 1861 and 1990.

Median ages of marriage rose to maxima in the 1930s and 1940s, then fell steeply, levelling out latterly. Permanent celibacy was consistently high among females, but rose from much lower levels in males to maxima in the 1970s and 1980s. It is concluded that in these populations age at marriage and the extent of permanent celibacy are largely independent of one another.

In both islands the overall probabilities of females marrying fell until the 1920s, and then rose. The last decades showed stability (Barra) and a fall (Harris). Males showed only slight falls to about 1910; data were absent for between 1911 and 1960, but subsequently there was little rise in probability.

These overall changes seemed to be associated with reciprocal variations in probabilities in the younger and older age groups. Declining overall probabilities were associated with declines in younger and increases in older age-group probabilities, and vice versa.

Non-parametric correlations between median ages of marriage and probability of marriage were negative and generally significant for the 15–19 age group. Among the older age groups coefficients were generally positive.

There was some evidence of an association between probability of marriage and sex ratio in any group of potential mates. The effect appeared more marked among 15- to 19-year-old females.

Local factors which might explain at least part of the decline in nuptiality for the greater part of the period under study include the decline in the fishing industry and the ‘land hunger’ which existed until the late 1920s. This decline is interpreted as a ‘Malthusian’ response to economic and social conditions, but it coexisted with a ‘neo-Malthusian’ strategy, in the shape of declining marital fertility. The ‘Malthusian’strategy seems to have been largely abandoned around the 1950s, but it may have reappeared during the 1980s.

Beliefs about child illness were investigated using semi-structured interviews with mothers and providers in four rural Guatemalan communities. The two most common forms of child illness in Guatemala – diarrhoea and respiratory disease – were focused upon. These illnesses are particularly difficult to prevent and treat, especially with the rudimentary health services available in rural areas of developing countries. Comparisons with other ethnographic studies in Guatemala suggest that some traditional models of illness causation identified in these earlier investigations are relatively unimportant in the communities studied here. This finding, in conjunction with frequent responses related to hygiene and water, suggests that traditional explanations may be co-existing with biomedical views of illness causation to a greater degree today than in the past.

Endogenous ultradian rhythms with a periodicity of 2–3 hours operate separately in the right and left hemispheres of the human brain and modulate physiological functions, perception and cognition. Since sensory pathways from either hand terminate in the contralateral hemisphere, ultradian rhythms of the right and left brain can be monitored by variations in the tactile discrimination of the left and right hand, respectively. Thirteen right-handed German males were tested every 15 minutes for 8 hours. Time series of the tactile error rate determined for the right and left hands oscillate with significantly different ultradian periodicities. Whereas cycles in tactile discrimination of the right hand (left hemisphere) have a periodicity of about 2 hours, tactile discrimination of the left hand (right hemisphere) is modulated by longer periods of about 3 hours. This is interpreted in terms of the overall functional asymmetry of the human brain. Since the left brain is the specialized locus for verbal processing and the right brain for visual–spatial processing, lateralized ultradian rhythms operating in the hemispheres may provide a distinct frame for long-term timing of neuronal processes underlying semantic and spatial mapping of the environment. This is particularly important for interpreting biosocial behavioural rhythms seen in humans living under natural conditions.

Lateralized ultradian rhythms oscillating separately in the right and left hemispheres of the human brain can be monitored by variations in the tactile discrimination of either hand. A previous study in male German subjects has shown that the tactile error rates determined for the right and left hands oscillate with significantly different periodicities. In the present study, a group of Kenyan Maasai shepherds was tested while the subjects were leading herds on daily feeding routes. The Maasai exhibit considerable ultradian rhythms of about 2 hours in tactile error rates of either hand, but in contrast to the German subjects there is no significant difference between the right and left side. While an individual is en route, his hemispheres proceed through alternating states in matching segments of the path. Ultradian rhythms thus ‘scan’ not only the time of day but also the space, and might provide an intrinsic time-frame for neuronal processes of cognitive mapping.

The ‘insurance ova’ hypothesis (Anderson, 1990) views dizygotic twinning as a by-product of selection for multiple ovulation which sometimes – in error – results in the birth of twins. From this viewpoint, polyovulation is a mechanism which reduces the risks of fertilization failure or embryo defect/mortality. If DZ twin births are a ‘side-effect’ of a mechanism which compensates for defective embryos one might predict that embryo defect rates and twinning rates will covary. This prediction is tested using national-level data on twinning rates and rates of trisomy-21 (Down's syndrome), and a strong positive correlation is found, even when controlling for maternal age. One suggestion that follows from this finding is that intra- and interpopulation variation in both twinning rates and Down's syndrome rates may result, in part, from individual variation in pre-implantation rejection of embryos in the very early stages of pregnancy. In this paper it is proposed that the ‘insurance ova’ explanation for twinning in humans could be expanded to incorporate a model of rejection of anomalous embryos, be they anomalies of number or type. Variation in the efficiency of an embryo rejection mechanism, combined with variation in frequency of polyovulation, would have consequences for individual reproductive success.

There is increasing evidence that age at menarche has decreased in Europe and the United States during the last century and in Japan over the last several decades. Data from a community-based survey conducted in two rural counties of Anhui Province in China indicate a similar, downward secular trend in age at menarche for Chinese women. The present study shows the mean age at menarche decreased by 2·8 years, from 16·5 to 13·7, over an approximate 40-year time interval. This rapid decrease in age at menarche may partly be due to better nutrition and living standards reflected by the improved socioeconomic standards experienced in China over the past few decades. To test this hypothesis, a number of determinants of age at menarche were assessed; year of birth, literacy status, county of residence, amount of physical labour, general health status, pesticide exposure before age at menarche, and drinking water source were all found to be associated with age at menarche.

Epidemiological studies have revealed that stressful changes in social environment increase the risk of cardiovascular mortality. In this study, the influence of major negative and positive life changes on serum cholesterol was examined in middle-aged men to determine a possible biochemical link between life changes and cardiovascular mortality. The results showed no influence of negative life changes on serum cholesterols. However, positive life changes significantly predicted a reduction in total and LDL (low-density lipoprotein) cholesterol levels after adjustment for the baseline cardiovascular health status, baseline cholesterol level, diet, body mass index, waist-to-hip ratio and cardiorespiratory fitness. The odds ratio for lowering LDL cholesterol was 5·2 in the men reporting positive events compared with those reporting none. The findings suggest a predictive value of positive life changes for atherogenic lipid profile in middle-aged men.

The surnames of the 3443 males registered to vote in Kidlington in 1977 yield a Coefficient of Relationship by Isonymy of 0·000564 {Ri=Σ(n(n–1))/2 N(N–1), in which n=the number of men of each surname and N=Σn}. Those of the four wards separately average 0·000722. However, if one includes only one male of any one surname in each residence, the values are, respectively, 0·000534 and 0·000535. That is, the only structure seen between the two levels is in the influence of men of the same surname resident in the same house. An analysis of relationship by residence on the same street yields a value of Ri somewhat higher than that for the ward as a whole, however, suggesting that even within a ward there may be a tendency for the house of relatives occasionally to lie close together.