Consider the colon

There's a rather interesting article at Scientific American:

Human Ancestors Were Nearly All Vegetarians

and I thought this paragraph, taking a sort of comparative overview of our digestive systems, was pretty interesting:

Our guts are remarkably similar to those of chimpanzees and orangutans--gorillas are a bit special--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 variation. In the leaf-eating black and white colobus monkeys (among which my wife and I once lived in Boabeng-Fiema, Ghana) 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 similarly disproportionate role, albeit later on in digestion. 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, relatively generalized monkey/ape guts. Our guts are distinguished primarily (aside from our slightly enlarged appendix) by what they are missing rather than what they uniquely possess. Our large intestines are shorter than those of living apes relative to the overall size of our gut (more like 25 percent of the whole, compared to 46 percent of the whole in chimps). This shortness appears to make us less able to obtain nutrients from the cellulose in plant material than are other primates though the data are far from clear-cut. The variation in the size and details of our large intestines relative to those of apes or gorillas have not been very well considered. In a 1925 study the size of colons was found to vary from one country to the next with the average Russian apparently having a colon five feet longer than the average Turk. Presumably the differences among regions in colon length are genetically based. It also seems likely that the true human colonic diversity has not yet been characterized (the above study considered only Europe). Because of the differences in our colons (and ultimately the number of bacteria in them) we must also vary in how effectively we turn cellulose and other hard to break down plant material into fatty acids. One measure of the inefficiency of our colons is our farting, which we all know varies person to person. Each stinking fart is filled with a measure of our variety.³ Aside then from the modest size of our colon, our guts are strikingly, elegantly, obviously, ordinary.