This section is from the book "Man: A History Of The Human Body", by Arthur Keith, Sir. Also available from Amazon: Man: A History Of The Human Body.
Some years ago Mr. Havelock Ellis collected all the observations which have been recorded regarding the differences between the body and mind of man and woman and made them into a most interesting and valuable book. From the crown of her head to the sole of her foot woman's body differs from man's. She buttons her dress differently, she walks, speaks, and breathes differently. We are so accustomed to the division of mankind into two forms that we never think of the possibility of man and woman being formed alike. Our business in this chapter, however, is not to picture a world populated with men and women, alike in mind and body, except in the essential parts relating to sex. Our purpose is to see what light we can obtain on the origin of the sexual differentiation of mankind, and ascertain if possible how and why the two sexes have been endowed with different characters.
Now, although the thousand and one characters which, have been enumerated by Mr. Havelock Ellis distinguish the parts of the female body from the male, there do occur cases where the distinctions are but ill-defined. It is not necessary to say that occasionally women appear to assume the form of body and features of face we associate with men, while just as frequently we see men who are feminine in their stature and build. In such cases, where we have only a part of the body to provide us with the necessary evidence, it may be difficult or even impossible to determine the sex. This was forcibly brought home to the writer a few months ago when a complete skeleton was excavated on the coast of Essex by Mr. Hazzeldine Warren. It was proved from the objects found with it, and from the stratum in which it lay, that the individual whose skeleton was thus found, had lived 4,000 years or more ago—when the natives of England used rough pottery for cooking and flint knives for cutting. When Mr. Warren brought the skeleton to me I lifted the skull from the box and said it was that of a woman. My judgment was founded on several of its characters. The first and chief was that the bony ridges which give attachment for the muscles of mastication and for those of the neck were not so strongly marked as in the male sex, for in a man these muscles are usually strong and their impressions very distinct. The impressions on the base of the skull for the attachment of the neck indicated K the tapering, slender neck of a woman, not the thicker and stronger neck of a man. The bony ridges which cross the forehead were not prominent as is the rule in men. The face, too, was moderately long, oval and slender in form, while the teeth, although well developed and somewhat worn, were small in size when compared with those of a typical man. The skull was small in size. On an average the cavity of the skull of a man holds 140 cubic centimetres (five ounces) more than that of a woman, and is a quarter of an inch longer and one-sixth of an inch wider. In these characters this skull corresponded to those of a woman. I concluded, therefore, that the skeleton must be that of a woman. The reader, however, is already aware that there is here and there a man with a skull which may answer to all of these tests.
Mr. Warren, however, had formed an opposite opinion as to sex, and drew my attention to the pelvis. That part of the skeleton as a rule affords undisputable evidence as regards sex. In the female it is widened so as to give passage to the child at birth. In the specimen from Essex there were all the outward appearances of the pelvis of a small and slender man. It was stout and muscular; the pelvic cavity was neither capacious nor shallow, nor was its outlet wide and roomy as in the typical female pelvis. Although a few of the minor characters of the pelvis were suggestive of the female sex, yet I had to agree with Mr. Warren that the major ones were masculine. There was no doubt as to the pelvis and the skull being parts of the same individual and yet there was apparently an incongruity between their sexual characters. The height of the skeleton indicated a person of 5 ft. 4 in. in stature, that is only half an inch more than the stature of an average woman and three and a half inches less than an average man. The stature indicated again the female sex, but all of us have seen women of 5 ft. 8 in. and men of 5 ft. 4 in. The thigh-bones, the bones of the arm and of the leg were slender, but still not so finely marked as to exclude the male sex. The bones of the hands and feet were small; these were female characters. When, however, we came to examine the ribs, the breast-bone and the chest as a whole, all question as to sex was settled. The breastbone was of the short wide form which is only seen in women. When the ribs, which were rounded and rather slender in form, were placed in position, it was seen that the thorax was well formed in the upper part, as is usual in women, and fell away in the lower part so as to conform to a narrowing at the waist. When the pelvis was placed in its proper position as regards the thorax it became evident that in spite of its masculine characters it was much wider than the thorax. The width of the lower or pelvic part of the body as compared with the breadth of the thorax is a striking feature of the female body. In males the pelvis is usually narrower than the chest. In statues and paintings of the nude, this character of the female body is always to be seen. A certain degree of narrowing at the waist is natural to a woman, for we are dealing here with one who lived long before the days of corsets. The short breast-bone, the well developed upper part of the chest are adaptations to woman's natural method of breathing. She uses the upper part of her chest more than the lower part in breathing, while men usually do the opposite. It is true that this statement has been denied and that observations made on primitive races have been published to show that man and woman, in a condition of nature, breathe alike. My own observations point to an exactly opposite conclusion, and in this I am in agreement with the majority of students of the human body. There can be little doubt that woman's breathing is modified so as to minimise the pressure to which the developing foetus would be subjected in the later months of child bearing if the type of breathing were abdominal or diaphragmatic as in the male.
 
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