The title I have been asked to discuss is the Coordination' of Reproductive Processes and this implies that there are many structures and functions to be coordinated. Text-fig. 1 gives a general idea of what these structures and functions are. The basal region of the brain, known as the hypothalamus, is played upon by many stimuli from the external environment acting through different nerve tracts. The hypothalamus in turn regulates, through a system of small vessels, the secretory activity of the anterior pituitary gland, which for the purposes of reproduction secretes two or three gonadotrophic hormones into the bloodstream. These hormones are very largely, if not entirely, responsible for maintaining the activity of the ovary and the testis, and for varying and regulating the processes going on in the gonad. The gonad in turn secretes into the bloodstream simpler steroid hormones, which act upon the reproductive tract and the mammary glands.

The word environment is here used to mean the total environment, physical and social, which for man means primarily the climatic and cultural conditions under which he lives and breeds. Fertility is used in the demographic sense of reproductive performance as contrasted with fecundity, or potential reproductive capacity.

Owing to the rarity of triplets and higher multiple births, most studies of multiple births have been focused on twins. One of the fields of study which has attracted considerable interest is the association of biosocial factors with twinning. Although much work has been done in this field in Caucasian populations, very little investigation has been carried out in tropical areas, some of which have the highest twinning rates on record. In this paper, the results of recent studies on twinning conducted in Aberdeen (Scotland) and Ibadan (Nigeria) will be presented to illustrate the influence of some biosocial factors on twinning.

Sir David Owen, who should have given this lecture, died very suddenly and unexpectedly at the end of June.

U Thant said in a tribute: ‘David Owen was literally the first member of the United Nations Secretariat. He joined the United Nations directly from the San Francisco Conference in 1945…. As the first and only Executive Chairman of the Technical Assistance Board he was key organizer of what has now become the United Nations Development Programme…. When he left the United Nations a year ago to assume his new post as Secretary General of the International Planned Parenthood Federation he was continuing the work to which he had devoted his life, the application of human ingenuity and technological progress to problems of peoples of the world. It is a tragedy, and a loss to all mankind, that his life and his new career have been so abruptly cut short.’

The reproductive behaviour of human beings, in contrast to that of other animals, is distinguished by almost universal awareness of the connection between sexual activity on the one hand and the birth of children on the other. There are, it is true, some classic examples where this connection apparently is not appreciated, as for example, the Trobrianders as described by Malinowski (1937), and the Arunta of the Central Australian desert as described by Spencer & Gillen (1927). These, however, are exceptions rather than the rule. In any case, even in them, reproductive behaviour is still constrained by custom although the connection is not appreciated. The biological potential to reproduction therefore does not, in itself, determine the level of fertility in any human population. Some individuals, or some categories of persons, may deliberately attempt to influence the natural process of reproduction, either to enhance or to inhibit its efficacy.

The contrast in birth rates in England and Wales between the periods on either side of the peak in 1964 is described and its components discussed. The drop after 1964 is mainly due to a drop in marital fertility at all ages, and especially the youngest. There is, however, as yet no evidence for a fall in the completed fertility of recent cohorts although their birth intervals are clearly lengthening. The mechanisms of such a change are described and their relative importance suggested. It is concluded that ultimate responsibility for the changing tempo of recent British fertility lies with fluctuations in the economic situation of the country.

This paper attempts a new look at an old problem. Throughout this century there have been many reports showing that certain characteristics of family structure are associated with the individual's performance in evaluative situations, be these IQ tests, tests of achievement, school and university examinations and even occupational success (for an excellent summary, see Anastasi, 1956). It is well known, for example, that children from large families tend not to do so well in such situations as children from small families, and that this phenomenon appears to be, in some degree, independent of socio-economic differences. This we can illustrate with our own data (Text-fig. 1) in which we see a steady decline in score on a nonverbal group test of intelligence as the size of the family increases. Less clear is whether other features of family composition, such as the spacing between siblings, the sex composition of the sibship and the ordinal position of the individual within the sibship, also affect achievement. (There is no lack of reports but, as we shall show, the evidence they provide is conflicting.)

I am honoured to be asked to give the Galton Lecture and, as an obstetrician, I am particularly glad to give it in the context of this symposium devoted to biosocial aspects of fertility.

By comparison with the frightening problems of population control on a world scale, the control of Britain's population should be easy but, unfortunately, it has not been tackled with the urgency it demands. In the North East of Scotland, however, considerable progress has been made. We have a natural human laboratory for the study of this problem and other aspects of human reproduction. It has the advantage of relative isolation, homogeneous population, convenient size (half a million) and availability of scientific personnel from Research Institutes, University and National Health Service. In addition, very good relations exist between these bodies and the general public. Continuity of medical care facilitates long-term study of patients, assessment of needs and results of treatment. The people have become knowledgeable and co-operative.

When the first Eugenics Society Symposium (Meade & Parkes, 1965) was held in 1964, its final session, on ‘Aspects of Fertility Control’, included two papers (Peberdy, 1965; Morgan, 1965) describing experimental family planning services, which offered advice and treatment in their own homes to the ‘problem parents’ of large families in the lower working class. These two projects, established from 1959 onwards in Newcastle and Southampton, together with a similar service pioneered in York by Dr Dronfield, have been used as models for subsequent ‘domiciliary family planning services’, and an account of one (Brittan, 1964) has been reprinted by the FPA as an information leaflet.

This is a subject in which one can readily become entangled in semantic confusion. Short definitions of the unwanted pregnancy are always inadequate and I am going to assume that we all know what we mean by the term. I would comment that a planned pregnancy is a wanted pregnancy, but not all unplanned pregnancies are ultimately unwanted. Many of us here could, in truth, be described as more or less happy accidents.

Sir Dugald Baird, in his Galton Lecture to this Society earlier in this Symposium, suggested that the obstetrician in society should no longer aim to acquire all the skills previously encompassed in obstetrics and gynaecology. Instead, he should develop some special interests, and then make his contribution to society by being part of a team of colleagues. One such special interest is the dissemination of factual knowledge and of an enlightened and enquiring attitude to sex and reproduction among the population at large.