I’m not sure what you’ve got in mind there, but it would be worth looking at whether there are some tradeoffs between being able to give birth easily and how good a woman is at walking and/or running.
The larger the hip the easier it is to give birth but the less efficient the gait becomes for a bipedal animal, since at each step the projection of the center of mass on the ground is horizontally farther from the foot. That’s the reason why women swing their hips much more than men as they walk. While it looks sexy it is not very evolutionary advantageous if a saber-toothed cat is chasing you.
Birds and bipedal reptiles don’t have that problem though, since their birth canal does not pass between the hip bones, thus they can get away with horizontally small hips and still be able to lay eggs which in some species can be as large as one fifth of the their body.
While in hunter gatherer times it would have been important to run fast, as civilisation arises you get chased by bears less often, and so I could guess that hips would start to become wider.
I’m not sure what you’ve got in mind there, but it would be worth looking at whether there are some tradeoffs between being able to give birth easily and how good a woman is at walking and/or running.
The larger the hip the easier it is to give birth but the less efficient the gait becomes for a bipedal animal, since at each step the projection of the center of mass on the ground is horizontally farther from the foot.
That’s the reason why women swing their hips much more than men as they walk. While it looks sexy it is not very evolutionary advantageous if a saber-toothed cat is chasing you.
Birds and bipedal reptiles don’t have that problem though, since their birth canal does not pass between the hip bones, thus they can get away with horizontally small hips and still be able to lay eggs which in some species can be as large as one fifth of the their body.
While in hunter gatherer times it would have been important to run fast, as civilisation arises you get chased by bears less often, and so I could guess that hips would start to become wider.
The hips already became a lot wider X-/ along with other body parts.
And given contemporary medicine, a narrow pelvis isn’t really a big deal nowadays.