It is difficult to get to the origins of the development of the pelvis (pelvis) by sex, as this skeletal fragment is generally not well preserved in fossils. Therefore, it was not known whether the differentiation in the pelvis developed during the transition to walking upright on two legs or later due to the enlargement of the brain.
A group of scientists from the University of Calgary studied pelvis bones in humans and chimpanzees. In chimpanzees, humans’ closest relatives, birth is easier because the baby is smaller. However, thanks to 3D analysis of the pelvis bones, it was seen that the females and males of chimpanzees were of different sizes, just like in humans. The researchers therefore concluded that the difference existed in the common ancestor of the two species, and therefore in all extinct human species. That is, the pelvis of the Neanderthal woman was also wider than that of the man.
The difference in the pelvis is actually found in all mammals. The pelvis is wider, especially in female bats and some female primates, which give birth to larger offspring for the size of the birth canal. Even in some species that give birth to very small offspring, such as cats or opossums, the difference between the pelvis is similar to that of a human. When people walk upright on two legs and have a larger brain, the pelvis may also be more developed in women.