Centaur biology

Who doesn't love reading intelligently-written pieces on stupid subjects?

I've always found the biology of centaurs to be confusing. Mythical animals typically have some basis in the animal kingdom, but simply grafting a human torso onto the shoulders of a horse brings some serious logistical problems. Does the horse-torso have lungs too? Are nearly all organ systems redundant? Is the human-torso bladder missing?

I recently discovered an in-depth piece on centaur anatomy written by Dr. H.C. Reinhard V. Putz in the Annals of Improbable Research that explores these issues with mock seriousness.

He proposes that some systems, like the nervous system, would have a single unified system through both torsos and others would have dual systems in both torsos, such as a heart in each chest, for the circulatory, digestive and urogenital systems.

One troubling thought does remain. As Dr. Putz said, mythology depicts centaurs as eating human food and not horse food. This is logical as they had human teeth and jaws, however it presents a nutritional problem. Horses need massive amounts of food to feed their large bodies and centaurs have even more mass with the extra torso but a smaller mouth. That means they would have to spend most of their time feeding to maintain their body weight, much like the common hummingbird.

Perhaps centaurs would have been more practical if it had a way of drawing nutrition from a symbiotic species, such as a human body with a horse-like head for feeding.