The significance of nuptiality with respect to interpretation of sex differences.

Existence of sex differentials with respect to disease in human populations is a matter which deserves investigation both from a practical and from a theoretical viewpoint. At the operational level, their interest scarcely calls for comment; but the biological significance we attach to them is an issue we are prone to dismiss too lightly by undue reliance on experience of laboratory stocks. In one way or another, most human societies are polarized with respect to the prevailing pattern of occupation in which one or other sex is engaged. Hence statistical regularities characteristic of the sex difference may well arise in virtue of hazards peculiar to different occupations in contradistinction to agencies ultimately traceable to the X-chromosome complement. If a wholly decisive test for discrimination between these possibilities or for evaluation of their relative importance in a given situation is not available, there is at least one framework of com parison relevant to a balanced judgment. On the whole, single females, if adult, have gainful employ ment outside the home, as do the majority of men. To this extent, we are entitled to expect that sex differences, if attributable to differential occupational risk, will be less obtrusive if we restrict our com parison to unmarried women. This does not mean that a sex differential attributable wholly or largely to circumstances unconnected with constitutional differences will disappear if we confine our compari son to men as a whole and to single women only. We must not disregard the fact that single women and men, if gainfully employed, dominate different trades and professions. For instance, men dominate the heavy industries and single women predominate in domestic and cognate services, including the care of children and the sick. It is none the less broadly true that the daily regime of the single woman conforms more to that of the male than does that of the married woman. In so far as the morbidity experience of the single woman conforms more to the male pattern we have therefore good grounds for assuming that differences which distinguish women as a whole are appreciably attributable to occupational status. The converse is not true, inasmuch as a difference which distin guishes the sexes may be associated with an occupa tional hazard almost or wholly restricted to males. Needless to say any comparison undertaken with this end in view is liable to lead us grossly astray if we do not pay attention to the differential incidence of disease with respect to age. Accordingly, comparisons of the mortality experience of men with that of women, or of single women with that of married women should take within their scope a breakdown with regard to age of the relevant populations at risk. This communication is an exam ination of what materials official statistics of disease supply. 2. Sources of Figures