The problem with pelvis expansion is it is hard to select for widening of the pelvis without upsetting walking and running. Development is hierarchical and bone

The problem with pelvis expansion is it is hard to select for widening of the pelvis without upsetting walking and running. Development is hierarchical and bones are lower down in the heirachy than brain size. In regards Neanderthals I would not be surprised if it was wider pelvis that allowed for them to have larger brained babies. This is a fascinating area.