The shift in the marital structure of Nepal between 1961 and 1971 has been analysed, and its implications for the CBR in 1971, Although there has been a slight increase in the age at marriage, over 90% of Nepali women were married by the ages of 20–24 years in 1971 and the overall marital structure of 1971 is more favourable to a higher CBR than the structure at the beginning of the decade. This is primarily due to a decline in the incidence of widowhood which has increased the proportions of potential child-bearing women and consequently the number of births. Thus shifts in the marital structure between 1961 and 1971 could have provided little impetus to a decline in the CBR of the country.

A study of a group of highly fertile women indicated that the majority tended to adopt a fatalistic approach to having children.

An exploratory attempt to isolate those conditions which might be associated with this type of behaviour included consideration of the women's general attitudes towards planning or not planning their future, in relation to their socio-demographic background. The work represents a first step in developing more useful methods of investigating fatalistic approaches to pregnancy and childbirth.

A review of the pattern and magnitude of nero–white mating in the US is presented from the time of the earliest arrival of negroes in the American colonies until the present, using historical, demographic, census and genetic evidence.

The relative magnitude of negro male–white female matings compared to the converse are analysed in view of the different genetic outcomes of these two types of mating for X-linked genes. Contrary to many strongly stated opinions it is conclued from the historical evidence that, even from the earliest days of slavery, negro male–white female matings were a significant proportion of all negro–white matings. Census and demographic evidence suggests that their frequency increased so that from the time of the Civil War on they have formed a majority of inter-racial matings.

Genetic evidence based on estimates of the amout of admixture of white genes in a number of negro populations is considered. Estimates of admixture for the X-linked genes G6PD, and those for colour blindness are as high or higher than those derived from comparable autosomal genes.

Some observations on the total magnitude of negro–white mating, on the phenomenon of passing and on the relative socio-economic status of those involved are also made.

The implication of the findings on these phenomena for investigations and hypotheses concerning differences in intelligence and intellectual abilites between the races, particulary spatial ability which is thought to be strongly influenced by a gene on the X chromosome, are considered.

It is concluded that some of the assumptions made in proposing hypotheses regarding the origin and distribution of these abilities in the American negro are at variance with genetic, historical and sociological findings.

Semen and serum vitamin B12 levels in Indian lactovegetarian and non-vegetarian subjects were estimated along with routine semen examination. Lactovegetarians had distinctly lower serum and semen vitamin B12 levels than the non-vegetarians. However, in normal and oligospermic subjects the ratio of semen vitamin B12 to serum vitamin B12 in the various diet groups was not significantly different and was always greater than one. In azoospermic subjects the serum vitamin B12 levels were always higher than the corresponding semen vitamin B12 values. Although semen vitamin B12 content was related to serum vitamin B12 level and sperm concentration in the normal and oligospermic groups. Further, in healthy lactovegetarians with low serum and semen vitamin B12 content and oligospermia, treatment with hydroxocobalamin produced no significant improvement in semen quality.

Estimates of the incidence of illegally induced abortions are critically reviewed and on the basis of a revised estimate it is tentatively suggested that there were 50,000 (legal plus illegal) abortions induced annually between 1964 and 1966. A substantial reduction in the extent of illegal abortions is an important consequence of the 1967 Abortion Act. But induced abortion is seen as a contributory factor only in the decline of legitimate fertility which has been greater at all ages and all parities than the increment of abortions to married women. A particularly marked reduction in legitimate births occurred between 1972 and 1975 whereas the number of induced abortions performed on married women declined slightly. However, the reversal of the secular trend of increasing illegitimacy is evidence of the demographic impact of the Act. Regional rates of abortion are found to be unassociated with the decline in high parity births but nagatively associated with illegitimacy ratios. At the regional level differences in the proportion of abortions performed under the NHS remain. At the national level a lower proportion of early terminations occur in the public sector than in the private sector, and women in the least skilled occupational groups have their abortions latest.

The number of persons attempting suicide in 1972–3 was related to the 1971 Census data by enumeration district in a defined area centred on Oxford City. Variations among enumeration districts in the number of attempters was partly explined by the age and marital state distribution of the population, but a few areas were identified where the high rates were not accounted for in this way. These included areas on council estates, both in the City and outside it, with marked indications of social disadvantage, and a socially mixed and probably rapidly changing inner city area. Persons attempting suicide were predominantly young and included relatively more women and more single people, but otherwise appeared to resemble the population of their immediate areas in terms of distribution by socio-economic group, housing conditions and indicators of social disadvantage. A model was fitted to the 1972–3 data to ‘predict’ the number of attempters in an enumeration district from the Census information. The fit was not entirely satisfactory, and suggested that there was a sub-group of districts with a near zero probability of producing an attempter which was not identifiable from the Census data. When fitted retrospectively to attempted suicide data for 1969 the performance of the model was poor. It was not possible to distinguish the effect of random variation from that of systematic change, but there was some evidence that certain areas with high attempted suicide rates in the City also showed a rapid increase in rates.

An intensive pilot survey involving direct contact with 47 young married couples with university education was conducted to determone their attitudes tiwards general (public) and personal choice and control by parents of the sex of offspring. Information as to premarital family status and present number and sex of children was obained. Questionnaires were completed before and after information had provided regarding new methods of fetal sex detemination, abortion, and related topics. Opportunity for discussion by husband and wife between sessions was allowed, but discussion with other was discouraged. Results indicate that sex choice will be accepted and employed by the majority of highly educated, middle-class individuals. While selection of the first-child sex is of negligible importance to most, planning for a second child with opposite sex to the first is strongly favoured. The tendency to prefer males is not as pronounced as reported in previous, less direct studies. The majority preferred a two-child family with one child of each sex. Prospective methods (e.g. a pre-coital, sex-selective pill, when available) were much preferred to retrospective methods involving abortion. Inthe meantime, fetal sex determination in the first trimester of pregnancy with selective abortion may soon be widely practised. New problems in marital and family adjustment, family planning, and social organization may arise with the advent of this new step in human sexual socio-econtingencies need further onvestigation at various socia-economic and educational levels and in different cultural milieus.

A population–biological study of the Kota of the Nilgiri Hills was undertaken between May 1966 and January 1968. This paper discusses the demographic structure of the tribe and its genetic implications.

The Kota is a small tribe of 1203 individuals distributed in only seven villages; it is an isolated population with a low rate of fertility and a high rate of infant mortality. The Kota is not a random mating population. The rate of consanguineous marriages is high and the coefficient of inbreeding is almost equal to the highest recorded value. Besides cousin marriages, marriage within the village is very much preferred. The admixture rate (0·29%) among the Kota is very low. The effective population size is only 28·87% of the total population. The coefficient of breeding isolation is 1·01, which indicates that genetic drift may produce important differentiation in this population. The data show that selection is acting with moderate intensity in this population.

Data are employed from six surveys carried out in Ibadan City, Nigeria, during two survey programmes: the Nigerian segment of the Changing African Family Project in 1973, and the Nigerian Family Study in 1974–5. A distinction is made between contraceptive innovators, those who use any means to control fertility except the traditional Yoruba sexual abstinence, and demographic innovators, those who succeed in limiting their family size. It is shown that contraceptive innovation is now proceeding rapidly but has little connection with demographic innovation. Contraceptive innovation is a response to social change which has increased the likelihood of premarital and extramarital sexual relations and the desire to shorten the period of postnatal sexual abstinence while not increasing the interval between births. Such innovation has proceeded more rapidly because of the increased availability of contraceptives since about 1960 and because of the types of contraceptives which have been developed since then. Demographic innovation is on the increase but its incidence is still minute. Fertility restriction within marriages seems to take place only after profound changes have occurred in the economic relationships within both the extended and nuclear families which for the first time make the small family the economically rational choice. Such change probably depends more on the import of cultural patterns than on necessary cultural adjustments to imported economic change, but a strengthening of the conjugal bond is involved and this may be hastened by contraceptive innovation. Little innovational trauma or even awareness of profound change was detected, largely because the profound, and even disruptive, innovations are preceding social ones, but partly too because peer group behaviour changes at much the same time.

Interviews were carried out with 979 women attending a clinic for birth control advice. Most of the patients were single, middle-class women who worked in central London offices. More than 600 had never approached their GP for advice; of these, about 200 were reluctant to do so because of embarrassment or fear of the reception they might get. Those that did visit a GP intially tended to complain of a lack of interest. Fewer patients who had sought help from a local family planning clinic expressed a similar dissatisfaction but one-third did criticize the facilities and service provided. Two-thirds of the patients were surprisingly ignorant about the contraceptive facilities available in the areas in which they lived.

The variables maternal age, paternal age, and birth order are studied for possible effects on the human secondary sex ratio. Several multivariate models are applied to a set of over 1·4 million births to assess the effects of these three highly correlated variables. Also investigated is the polynomial regression model used by Novitski & Kimball (1958) in their approach to the same problem. Analysis of the present data shows a weak and negative association between sex ratio and birth order and the suggestion of a similar association with paternal age.

The hypothesis that among attempted suicides, severity of intent to die is unrelated to the menstrual cycle was investigated in a sample of regularly menstruating women, using a validated intent scale. Women making their suicide attempts in the premenstrual week demonstrated a significantly higher suicidal intent but no differences in respect of other variables were observed.

The agreement between zygosity diagnosis in twins by reference to the twins' own answers to written questions and diagnosis based on an objective assessment of zygosity by blood-typing is studied for 178 pairs of same sex twins. Seventy-two female and 106 male twin pairs answered two questions concerning their similarity in appearance and frequency of confusion in childhood, and were blood-grouped using up to 23 different antisera. Of those pairs concordant for all markers and diagnosed as MZ, 98% agreed that they were confused in childhood and that they are alike in physical appearance. Only 55% of those pairs discordant for at least one marker and classified as DZ agreed that they were never confused and are not alike in appearance. The replies of the remaining 45% are spread over all the other combinations of responses. If all twins who agree that they were confused in childhood and are alike in appearance were to be classified as MZ on the basis of the questionnaire alone, and all others as DZ, the diagnoses of only seven pairs out of the total 178 (3–9%) would disagree with those based on blood group data.

Using data obtained from the Censuses of 1963 and 1971, the Socio-Economic Survey conducted from November 1969 to October 1970 and the Registrar General's Department, this paper analyses fertility trends in Sri Lanka during the period 1960–72 with special reference to the sub periods 1963–70 and 1963–71. The analysis indicates that changes in the proportion of women marrying was the most significant factor in the decline in the crude birth rate during 1963–70 and 1963–71. In the discussion on future prospects, attention is focused on the increase in contraceptive use from 1973 onwards together with other factors such as further postponement of marriage for women, a higher level of spinsterhood and emigration. The adverse effects on future fertility reduction of progressively larger female cohorts entering the main child-bearing years (20–34) are also discussed.

The differences between male and female performance in athletic track events at which both compete are compared. It is found that the difference between male and female performance as measured by world records is declining in all events and declining most rapidly in those events in which the differences at the present time are largest. Analysis of national track records for these same events shows considerable differences between different countries in average male/female differentials and the differences between males and females for some events in some countries is much smaller than world record differences.

It is concluded that social factors such as differing degrees of encouragement and differing levels of expectation are important factors in limiting female athletic performance.

The effect of four progestational drugs on the amount of milk yield in a group of lactating Egyptian women was estimated during the first year of lactation. The milk yield was highest in the women given Depo-Provera, followed by those receiving Deladroxone and quingestanol acetate. Only in those women given chlormadinone acetate was the milk yield, on average, lower than in the control group of non-medicated women.

A group of 20 brain-damaged (BD) subjects was added to the canonical analysis, reported earlier, of mandibular symphysis shape, in the following groups: (1) Down's syndrome (DS), (2) familial idiopathic sub-normality (FIS), (3) intermediate intelligence (II), and (4) high intelligence (HI). Significant separations between means were found for all pairs of groups, except only II–HI. The separation between the BD and FIS groups supports the hypothesis that a genetic mechanism (pleiotropy) underlies the link between intelligence and symphysis shape, but environmental influences probably account for most of the separation between the BD and the two normal groups. The findings have implications for the study of behaviour genetics

The differences between male and female performance in free style swimming events are compared. It is found that the differences between male and female performance, as measured by world records, is declining in all events and declining most rapidly in those events in which the differences at the present time are largest. Analysis of national records for these events shows important differences between different countries in average male/female differentials.

A different set of physical and physiological constraints operate on swimming compared to track performance, but they would seem to be less important in influencing male/female differences. Social factors also seem to be less important in swimming than in track athletics in perpetuating performance differences but are nevertheless still operative.