TheWaterRat

When our ancestors switched to hunting as a means of survival, new pressures came to bear on the human body. The males who set off on the chase had to develop improved respiration. If they ran out of breath they ran out of food. Compared to other monkeys and apes they had to become big-chested. The male chest became an athlete’s chest.

The female developed in a different way. Hampered by pregnancies and infants, she was less mobile. Her chest did not enlarge like the male’s. It developed in another direction, the rib-cage remaining small but the breasts swelling to a pair of soft hemispheres. These enlarged breasts had two biological functions, one parental, acting as gigantic sweat glands producing the modified sweat we call milk, and the other sexual.

While mother’s milk is ideal for growing a baby it has to be said that the shape of her breast is far from perfect for the task of breast-feeding; this is due to the sexual role of the breasts. This apparent flaw is explained by observing the breasts of monkeys and apes. In all other primate species the females are flat chested when not lactating. When they are breast-feeding, the region around the nipples becomes somewhat swollen with milk, but even then it is rare to find anything approaching the hemispherical shape of the human breast. The breasts of monkeys and apes are purely parental.

The origin of paired hemispheres of human female sexual signal is not hard to find. The females of all other primates display their sexual signals backwards from the rump region as they walk about on all fours. When the human female stands face-to-face with a male her rump-signals are concealed from view, but the evolution of a pair of mini-buttocks on her chest enables her to continue to transmit the primeval sexual signal without turning her back on her companion or going around on all fours.

In their sexual role the female breasts operate first as a visual stimuli and then as a tactile one.  Once the visual signals have attracted a male partner and sexual contact has begun, the tactile qualities of the breasts come into play. In pre-copulatory sequences there is often a great deal of oral and manual caressing of the breasts by the male. It is thought that the glands of the areolar region of the breast, during sexual activity, may transmit scent signals to the male nose exciting the male even more than the female. Which explains why males exploring their partners’ bodies spend so much time noising around in the mammary zone.

As sexual arousal mounts, the female chest undergoes several marked changes. The nipples become erect, increasing in length by up to a centimetre. The breasts become engorged with blood, increasing their overall size by up to 25 per cent and becoming more sensitive. With the approach of orgasm the areolar patches become tumescent and swell so much that they start to mask the nipple; there also appears a strange measles-like rash over the surface of the breasts and elsewhere on the chest, the ‘sex-flush’.

Few know that one every two hundred women have more than two breasts. The additional breasts are usually not functional .  Sometimes they are little more than additional nipples, sometime small breast-buds without nipples. The famous statue of the Venus of Milo, in the Louvre, displays three breasts, the third one being a small bud above the right breast.

The shape of the breast changes gradually from the age of puberty to old age.

The above is reproduced freely from ‘BODYWATCHING , A Field Guide to the Human Species’ by Desmond Morris.