Here's an interesting tidbit: Our aversion to all things disgusting may be rooted in a hardwired self-defense mechanism in our brain.

Researchers showed visitors (40,000...I'm thinking that is definitely statistically significant) images of items, varying in degrees of disgusting, from a muddy football to a gaping, infected wound (the responses were measured using the Disgustometer, a remarkably complicated rating scheme of 1 to 5, with 1 being not disgusting and 5 being *BARF*). People tended to rate the football as least disgusting, while the wound and other bodily fluids ranked much higher.

While that's all interesting, I personally take umbrage with the closing line of the article: "There is also evidence that animals have a disgust response. They, like humans, tend to avoid each others' feces. [1]"
Well, I'm annoyed by this on a few levels. First though, who ever wrote that statement obviously never tried to raise a dog and a cat simultaneously. I swear to god, my dog had kitty litter on his nose everyday! Sure, the dog had issues, did I seek help? Heck no, I never had to clean out a litter box. We (my parents and I) eventually had to change his name to Sir Pooples.

Okay, so there's a bit of hyperbole in there; we did try to dissuade him from eating his "brother's" crap, but the fact that we had to encourage him to avoid it is proof enough to me that the closing line is a bunch of dung.

Also; Maybe they've got the whole thing backwards: They (the authors, that is) seem to be postulating that the disgust emotion will help steer us clear of "dangerous" things. They then go on to correlate the response in terms of sight, noting along the way that things that rank consistently higher in disgust-factor also smell worse (a clean wound vs. an infected wound. A muddy football vs. anything more odorous than a muddy football, yet still with the same general appearance, etc.) What they're trying to prove is that our ability to see disgusting things is all it takes to avoid disease!

Here's an example...let's say you're in a well-lit room with a tray of freshly baked brownies that smell, literally, like poo. Do you eat them just because they look harmless?
Now let's say you're in a pitch black room, and there's the oppressive stench of feces present. Do you stick around just because you don't see anything, or do you get the heck out of there?

Sight has nothing to do with it. If it did, then they should be able to provide the additional proof of hundreds of dead/dying/diseased blind people, who didn't know any better, and ate a turd. There are plenty of healthy, living sighted people walking around, and there's also a bunch of blind people around (they seem to always be driving around me whenever I'm on the road), but how many smell-impaired people do you know? See? We don't even have a WORD for people like that, because, they don't last...they eat a turd, and die*.

Aaagh!...I get so angry.

*- I, in fact, do know someone with no sense of smell, but she's a PhD, and lost it due to chemical exposure before OSHA. Nice lady, but a terrible cook...