Differences in male and female physiology and structure have a long evolutionary past. As modern science has theorized of our “Hunter and Gatherer” ancestors, a few contemporary facts have surfaced as evidence for our explanations. Essentially, since men were the perceived “Hunters” they needed a slightly more motion efficient anatomy as well as more muscle and bone strength. Women are hypothesized to have been more stagnant but of course the predominant differentiating factor here is childbirth. This illustrates possibly the most notable difference in the male and female pelvises: the internal width. In general, male pelvises are thicker but more compact relative to the female's wider, oval shaped basin.
The next essential function of the pelvis is the angle at which it relates to the femur, the large upper leg bone. In bipeds, the foot must be beneath the center of an individual's gravity in order to maintain balance and locomotion. To achieve this, the bipedal leg is angled from the hip socket to the knee. In males, this angle is less than in females which indicates enhanced mobility. This also allows the Gluteus muscles of the female to avoid obstruction of the birth canal where contraction could injure a baby. The angles are dictated by the Inferior Pubic Ramii which are more concave in females and straight in males.
Another difference related to childbirth is the Sacral Promontory, the fused vertebrae that form the stem of the tail bone and posterior of the pelvis. In males, the promontory is much more pronounced while the female form follows its essential oval structure. It is important to note here that the pelvic canal is vertically cylindrical in females while it tapers in males. We can see this simple structural difference by looking downward into the pelvis of a human skeleton. In a male we could expect to see a smaller, heart shaped opening in the bottom while we should see a wider more circular opening in a female.
The Pubic Arch is also a significant item as it contains two unique differences between the sexes. In males, the angle under the pubic bone is narrower and deeper than in females.
Essentially there are three distinct and important differences in the male and female pelvis. The inlet, the canal, and the pubic arch. Within these structures we can see that men maintain thicker, more consolidated bones than the woman's rounded, column like pelvis. These differences have proved invaluable to the evolution of man through both sexes. They are also helpful to Anthropologists and Forensic scientists in determining the sex of a skeleton.
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