In the course of this century man's control over his natural environment and its effects has vastly increased. As a result, death rates from many illnesses caused by environmental factors have fallen markedly. This is very evident in the field of infant mortality. In 1906–10, of every 1000 babies born alive in this country, 117 died before their first birthday. By 1971–75 this figure had dropped to less than 17.

Detailed pedigrees of the small Samaritan isolate covering the last thirteen generations and consisting of 82 founders and 670 descendants allowed calculations of (a) the probability of origin of genes from particular founder members, and (b) the total number of descendants from each founder. Analysis of the matrix of distances between the thirteen generations identified the kind and the direction of the evolution of this community: rapid evolution from the first to the eighth generation due to the small population size, slowly progressing towards a stable state in the last three generations.

This paper examines data on fertility levels in 33 Moslem countries between 1960 and 1980. Fertility measures include crude birth rate, total fertility rate and age-specific birth rate, and the percentage change in them between 1960 and 1980.

The analysis focuses on: (1) the current status of Moslem fertility in comparison to non-Moslem countries in the same region; (2) the emerging fertility differentials among Moslem countries; (3) how much of the recent fertility declines in some Moslem countries is associated with modernization variables and with family planning efforts.

The results indicate that: (1) Moslem fertility remains universally high and is generally higher than in non-Moslem countries in the same region; (2) very few Moslem countries have succeeded in bringing down their level of fertility to justify a search for the predictors of Moslem fertility levels; (3) in spite of a sufficient range of variations in the economic and social correlates of fertility, the corresponding fertility variables in these countries do not suggest that the reproductive behaviour of Moslem women has reacted to such variations; (4) efforts directed towards stronger family planning programmes are clearly related to fertility decline.

The effect of the intermediate fertility variables on marital fertility in Kenya is examined using Bongaarts' model on group data from the Kenya Fertility Survey 1977/78. The findings suggest that variations in the proportion married among the population, level of contraceptive use and post-partum lactational infecundability can account for much but not all of the observed marital fertility differentials. Modernization through education and urbanization has had offsetting effects on fertility, by reducing lactation and increasing contraception. However, the proportion using contraception, limited mainly to those with secondary and higher education or metropolitan residence, is too small to have an appreciable impact on the overall level of fertility. The low level of marital fertility observed particularly among the metropolitan, coast and Muslim categories of population may be attributed to the prevalence of venereal diseases and unreported contraception and induced abortion.

The proportional hazards models of birth intervals based on the data from the 1976 Jordan Fertility Survey indicate that in Jordan the influence of infant death on subsequent fertility is not uniform among all population subgroups. Child survival seems to have only minimal influence on fertility among less educated women and women at low birth orders. In contrast, the probability of a subsequent birth increases significantly following an infant death among women in the high education class and among women in the high birth order group. The impact of infant death is similar among rural and urban women. Further analysis shows that the observed differences in the birth intervals of women with and without infant death experience cannot be attributed to the fecundity differentials of these two groups of women.

Since the end of World War II, the Guam native population, who are mostly Roman Catholics, has undergone one of the most dramatic socioeconomic developments ever recorded. They have rapidly become incorporated into the dominant American culture and economy. This accelerated process of modernization has been accompanied by a very sharp fertility decline. One reason for this decline has been the increasing defection of Guam Roman Catholic women from the traditional teaching of their Church on the subject of birth control. This trend of fertility decline, although at higher levels, resembles that of East Asian countries with rapid fertility decline.

The voluntarily childless and parents of one child by choice might be expected to make strong use of sterilization. This study examined the reasons given by couples who were early articulators of voluntary childlessness, couples childless through postponement, and mothers of a single child, for selecting or avoiding sterilization. Early articulators were more likely to be sterilized and more often reported difficulties in arranging sterilization than did those who were postponing parenthood. Among the voluntarily childless and mothers of a single child who were not sterilized, respondents cited its finality, aversion to non-essential surgery, and satisfaction with present methods. Clinic data on requests for reversals of previous vasectomies revealed that neither the intentionally childless nor single child parents were over-represented among men seeking reversals.

Since 1975, sterilization operations, on both men and women, have been performed with increasing frequency within the National Health Service in the North Tyneside Area in north-east England. Some characteristics of people seeking this form of contraception are described, and selected aspects are compared with the results from earlier studies.

In a survey of Swiss couples, the husband-wife agreement on contraception (current use, and methods ever used) is high and husbands are generally as well informed on the use of contraceptive methods as their wives. The data indicate that the use of condoms may be underestimated in interviewing women only and that the contraceptive behaviour of a couple is related to the fertility preferences of both wife and husband.

A summary of 298 male and 358 female respondents in the Lae urban area of Papua New Guinea in 1981 revealed a relatively high level of contraceptive awareness, but the level of contraceptive use is low. However, the overall current usages of non-traditional methods for the wives of the male and for the female respondents are 34–2% and 37% respectively. The male and the female respondents have the same views on the ideal family size—approximately three children.

This study employed similarity judgments to determine the dimensions used in distinguishing between methods of contraception, and to investigate individual differences in the use of these dimensions. Three groups of subjects rated the similarity of seventeen methods of contraception, and also rated each method on a number of adjective scales. Multidimensional scaling of the similarity judgments revealed two dimensions: one related to effectiveness, expense, and safety, and the other differentiating between standard and non-standard methods of contraception (or natural and non-natural ones). In addition, methods of contraception were arrayed in the space mainly on the basis of physical similarity. Analyses of the rating scales indicated that subjects perceived methods accurately in terms of effectiveness, but were inaccurate in their ratings of safety to the user. Finally, analysis of individual differences indicated that the second dimension was more salient to younger than to older subjects, but did not reveal differences related to religion or contraceptive use.

At the end of the fourth week of the Spring term 1982, 730 female undergraduates at Aberdeen University and 744 female under-graduates at Oxford University were sent a questionnaire enquiring about their sexual behaviour and contraceptive practice. Of the 978 unmarried women who replied, 507 (52%) had experienced sexual intercourse. No contraception had been used by 31% of the women on the first occasion that they had had intercourse; during the 4-week period preceding receipt of the questionnaire 14% of sexually active women had had intercourse on one or more occasions without a contraceptive. Twenty-nine women had been pregnant in the past; two women were known to be pregnant at the time of the survey and twelve women thought that they might be. These findings are discussed and some recommendations are put forward.

As part of a longitudinal study of diet and dental caries, 405 Northumberland children initially aged 11–12 years recorded the time of going to bed on 3 consecutive days on 5 occasions over a 23-month period. The bedtimes were recorded in a personal diary and checked at private interview. Mean bedtime for the 212 females changed from 21 hr 44 min at age 11 years 7 months to 22 hr 11 min at age 13 years 3 months. Bedtime for the 193 males was, on average, 9 min later than that for the females. There was a consistent relation between bedtime and social class, with social class IV + V children going to bed, on average, 14 min later than social class I + II children. When the average age of the children was 13 years 3 months, 13% of them went to bed at or after 23.00 hr, and they were latest to bed on Saturday when their average bedtime was 22 hr 59 min.