It sounds like there’s a lot of yet-unanswered questions here. If it is the size of the whole infant, why are our babies so big? If it’s not walking, could it be running? It does seem like human biomechanics requires a somewhat narrow hip bone, and I’m pretty sure I’ve seen statistical evidence that narrowness of the pelvis is tightly balanced against birth mortality in humans.
It sounds like there’s a lot of yet-unanswered questions here. If it is the size of the whole infant, why are our babies so big? If it’s not walking, could it be running? It does seem like human biomechanics requires a somewhat narrow hip bone, and I’m pretty sure I’ve seen statistical evidence that narrowness of the pelvis is tightly balanced against birth mortality in humans.