Civilization would not be civilization if we had to spend most of our time thinking about the biological basis. If we wish to think of "Nature's" proscriptions or plans as controlling animal life, the anthropomorphism is substantially harmless. But man keeps out of the way of most of such proscriptions, has plans of his own, and has acquired considerable skill in varying his projects without running foul of such biological prohibitions.
It is time to abandon the notion that biology prescribes in detail how we shall run society. True, this foundation has never received a surplus of intelligent consideration. Sometimes human societies have built so foolishly upon it that the result has been collapse. Somebody is always digging around it in quest of evidence of some vanished idyllic state of things which, having had and discarded, we should return to. This little excursion into biology is made in the full consciousness that social mandates are not to be found there. Human projects are the primary material of social science. It is indispensable to check these against biological fact, in order to ascertain which are feasible and which are not. The biological basis may help in explaining old social structures or in planning new ones; but much wild social theory has been born of a failure to appreciate the limitations of such material.
All the so-called higher animals, mammals and others, are divided into two sexes, male and female. Besides the differentiation of germ-cells there are rather obvious differences in the bodies of the two sexes. In common with many other mammals, the human male has a larger and stronger body, on an average, than has the human female. This is true also of the anthropoid apes, the species which most resemble man physically and are commonly supposed to be his nearest blood relatives in the animal kingdom. It has been true of man himself as far back as we have any records.
Such differences are only superficial—the real ones go deeper. We are not so much interested in how they originated in the world as in how they do come about in the individual. At least, we can come a good deal nearer ascertaining the latter than the former. In either case, our real purpose is to determine as nearly as possible what the unlikeness really consists of and so help people to sensibly make up their minds what can be done about it.
To define sex with rigid accuracy as the term applies to human beings, it is necessary to tell what it is in mammals, since man is a mammal. The presence of distinct body-cells is not peculiar to mammals, but there is one respect in which these latter are quite different from non-mammals: A mammalian individual, beginning like a non-mammal with a fertilized egg, has a period of intra-maternal development which a non-mammal has not. That is, a non-mammalian is a fertilized egg plus its parental (or extra-parental) environment; but a mammalian individual is a fertilized egg, plus its intra-maternal environment, plus its non-parental environment.
Here in a nutshell is the biological basis of sex problem in human society. Human individuals do wear out and have to be replaced by reproduction. In the reproductive process, the female, as in mammals generally, is specialized to provide an intra-maternal environment (approximately nine months in the human species) for each new individual, and lactation or suckling afterward. The biological phase of the sex problem in society consists in studying the nature of that specialization. From the purely sociological standpoint, the sex problem concerns the customs and institutions which have grown up or may grow up to meet the need of society for reproduction.
The point which most concerns us is in how far biological data can be applied to the sex problem in society. Systematic dissections or breeding experiments upon human beings, thought out in advance and under control in a laboratory, are subject to obvious limitations. Surgical operations, where careful data are kept, often answer the same purpose as concerns some details; but these alone would give us a fragmentary record of how a fertilized egg becomes a conscious human being of one sex or the other. The practice of medicine often throws light on important points. Observation of abnormal cases plays its part in adding to our knowledge. Carefully compiled records of what does occur in inheritance, while lacking many of the checks of planned and controlled experiments, to some extent take the place of the systematic breeding possible with animals. At best, however, the limitations in experimentation with human subjects would give us a rather disconnected record were it not for the data of experimental biology.
How may such biological material be safely used? Indiscriminately employed, it is worse than useless—it can be confusing or actually misleading. It is probably never safe to say, or even to infer directly, that because of this or that animal structure or behaviour we should do thus and so in human society. On this point sociology—especially the sociology of sex—must frankly admit its mistakes and break with much of its cherished past.
The social problem of sex consists of fitting the best possible institutions on to the biological foundation as we find it in the human species. Hence all our reasoning about which institution or custom is preferable must refer directly to the human bodies which compose society. We can use laboratory evidence about the bodies of other animals to help us in understanding the physical structure and functions of the human body; but we must stop trying to apply the sex-ways of birds, spiders or even cows (which are at least mammals) to human society, which is not made up of any of these.
It is possible to be quite sure that some facts carefully observed about mammals in a biological laboratory apply to similar structures in man, also a mammal. Because of this relationship, the data from medicine and surgery are priceless. Thus we are enabled to check up our systematic experimental knowledge of animals by an ascertained fact here and there in the human material, and to get a fairly exact idea of how great the correspondence actually is. Gaps thus filled in are narrow enough, and our certainty of the ground on either side sufficiently great, to give a good deal of justifiable assurance.