What is the evolutionary advantage of emesis (throwing up) in reaction to a fould odor?

Question

I know not all human characteristics have an evolutionary explanation, but how might this characteristic have benefited ancient human ancestors?

Answer 1

I agree with what others have posted, but want to consider the matter closer. Obviously, if you haven't eaten bad smelly food then throwing up is no advantage. Nor will you usually eat that which smells rotten, unless in extremis (I'm still amazed that we developed cheese. Mmmm, bluecheese...). I suspect that the answer is that nausea from smell is merely supposed to repress our impulse to consume. Since evolution works by small changes to existing structures, it propably devoloped in conjuntion with or from our tendency to throw up when feeling ill. I don't have any further insight into the evolution of the controls of our alimentary canal.

What always got me was my response to extreme height of vertigo. Talk about a time when I don't want to lose my sense of balance! :)

Answer 2

One advantage of throwing up is that (obviously) empties the stomach. This allows the body to concentrate blood flow to the brain and muscles in case you have to get away quickly.

I suppose it is also quite a strong reinforcement technique.

Answer 3

Spiteful Bill is right, ancient ancestors who threw up after eating stinky rotten carcass meat (or who were nauseated by its aroma, and so did not eat any) lived to hunt and breed another day. Those who ate the stinky meat got sick, and got weak, or maybe even died.

Answer 4

Traits don't have to have evolutionary advantages. They just don't have to be disadvantegous. It is a different, but slight.
If food is spoiled, perhaps, its odor might cause you to vomit so you don't consume them.

Answer 5

Maybe it is a byproduct of the "if this meat stinks, we shouldn't eat it" thing. The body gags and the Geico Caveman dines elsewhere.