It's the sort of question a child wonders out loud – usually very loud – in line at the grocery store, much to the horror of mom or dad. Still, how do pregnant women manage to haul their baby-filled bellies around without falling over?
Well, science is here to inform you, in the form of a study published in the journal Nature. Ladies can do something fancy with their backbones that men can't – they can compact the vertebrae in their lumbar area more easily. That means the bones in their lower backs are shaped more like wedges than those of males. So as women become increasingly pregnant, they can rock back on their spines to support and balance the additional weight [source: Whitcome]. Good thing too, for our species, don't you think?