This one is for the ladies, because the men probably won’t be able to sympathize. At least not as much as we should.
Ever wonder why pregnant women don’t just topple over and break their noses? Especially the ones that look like they mated with a bull elephant, and are carrying twins? How do they possibly carry all the extra weight around in that one, basketball shaped pouch between their breasts and their knees, without falling over? I know that I couldn’t do it. It’s hard enough carrying what I have.
Turns out I can’t. I don’t have the backbone for the job, but women do, because of evolution.
Our ancestors, way back when, tended to walk with the assistance of all four limbs, much like monkeys do now, so the females could support the extra weight with their hands. When we began to walk upright, however, the normal effects of gravity on the mass of the fetus approximately mid torso would have been enough to drive her forward, or, when compensating for it by leaning backward, exert unrelenting stress on the back muscles.
So evolution steps in and changes things. Women developed a change to the shape and function of the lower vertebrae that allowed the stress placed on the back by shifting her revised center of mass backward, so as to be more efficiently handled by the lower spine.
By comparing skeletal samples of men and women between the ages of 20 and 40, the researchers pinpointed the differences that allowed women to perform this balancing act. Women had three wedged vertebrae whereas men had only two, allowing the women to create a more extreme curve. In addition, the women’s facet joints, which connect the vertebrae and prevent twisting of the spine, were larger relative to their body size and positioned differently to redirect the weight and enhance resistance.
Men don’t have this adaptation, most likely because when we were lean, mean hunter-gatherers, before the invention of beer, and beer bellies, we didn’t need it.
(Click on graphic)
So, my male brethren, the next time you see a woman doing the pregnancy waddle, with that stance peculiar only to the soon-to-give-birth, (you know, belly out, hand on the small of back, shallow breathing) try to appreciate the fact that
god evolution has made her better than you.