for all of the vulgar and magnificent elaborations on the theme of tubes to be found inside animals, the guts of humans are boring. Our guts are remarkably similar to those of chimpanzees and orangutans (gorillas are a bit special) which are remarkably similar to those of other apes, which are, in turn, not so very different from those of most monkeys. If you were to sketch and then consider the guts of different monkeys, apes and humans you would stop before you were finished, unable to remember which ones you had drawn and which ones you had not. There is some variation. In the leaf-eating black and white colobus monkeys (among which my wife and I once lived) the stomach is modified into a giant fermentation flask, as if the colobus were kin to a cow. In leaf-eating howler monkeys the large intestine has become enlarged to take on a similar role. The alimentary canal varies tremendously, but in most species things are not so complex. An unelaborated stomach breaks down protein, a simple small intestine absorbs sugars and a large (but not huge) large intestine ferments whatever plant material is left over. Our guts do not seem to be specialized hominid guts; they are, instead, monkey/ape guts. The only real distinction between our guts and those of other primates, aside from a slightly enlarged appendix, is that we have slightly less large intestine relative to small intestine relative to other species, which might make our guts a little less efficient, though it might not (And even then such inefficiency wouldn’t predispose our bodies to any particular diet or culinary norm, it would just make us more likely to fart). Aside from the potential for farting, our guts are strikingly, elegantly, obviously, ordinary.

Rob Dunn, Scientific American Magazine