Why Pregnant Women Don’t Tip Over

Here’s an interesting article about evolutionary adjustments in female physiology to help cope with the effects of pregnancy:

Wedge-shaped vertebrae in the lower back might be the key evolutionary adaptation that helps human females maintain a stable posture over the course of pregnancy.

The article caught my attention initially because of the bit about wedge-shaped vertebrae. That is what I have which gives the hunchback look. Only it applies to pretty much all of my vertebrae, whereas the specific adaptation to help adjust a woman’s balance when the weight of an enlarged belly is added only applies to three vertebrae in the lower part of the back.

[…] the size of the joints relative to the vertebrae in the lower back is much larger in women than in men. This suggests that the joints’ larger surface area is an adaptation to bear more load.
And the shape of the vertebrae in women tapers off toward the back, creating a wedge shape that further facilitates arching, Whitcome said.
Women also have three such vertebrae, while men have just two.

I found this part of the article to be amusing:

[…] previously known about male-female differences in the shape of the pelvis related to birthing, […] spinal differences between males and females had not been appreciated until now.
“Like so many discoveries,” he added, “this is one that causes you to slap your forehead and exclaim, Of course! Why hasn’t anyone thought of this before?”

It does seem like a kind of logical thing, doesn’t it? But I suppose we have only had technology for x-raying and comparing many people’s spines for a relatively short time, and other technologies for viewing the spine of a pregnant woman with less risk than x-rays for even less time.

Why Pregnant Women Don’t Tip Over