Evolution Question

Vultures, insects, hyenas, and many other carnivores will eat carrion, meat that is in the process of decomposing / being consumed by bacteria.

Yet other carnivores, like man, are repulsed by the smell and taste of meat "gone bad."  My cereal this morning was ruined by a blueberry that tasted off.  Disgusting taste.

Why should this be so?  Wouldn't it make more sense for digestive systems of all animals to be able to process half-rotted meat, to find the bacteriological byproducts of decay palatable?  Would certainly make finding a meal easier.

You have to remember that evolution doesn't have a target. It doesn't aim for a best solution. Selection pressure is satisfied once survival and reproduction occur.

Eyes are helpful, so helpful that they've evolved several times. Why do our eyes have the retinal cells pointing the wrong way, so that the nerve has to go back through the retina, creating a blind spot? It doesn't have to be that way - octopus eyes are very similar to ours, except their retinas aren't inside out, so they don't have a blind spot.

The answer is that our eyes are good enough.

Why don't all meat eaters eat carrion? They don't have to. That's all.

Eyes are a "nice-to-have."

Eating is a necessity.

Why wouldn't evolution favor an organism that can consume carrion over one that can't or won't?

Catching live prey requires mobility and fitness and cunning and big teeth. By restricting a species to fresh meat you are requiring it to expend a lot of energy to stay alive.

That energy could be directed at reproducing instead.

If you were aiming at that target.

People don't eat carrion because much of the bacteria in it would kill the eater.
The reason that people find rotten meat disgusting is because that is a defensive mechanism to protect us from eating something that is not good for us.

Why didn't we evolve so that we could eat rotten meat? Apparently, there was no need for it, or - and more likely - the people who tried it pronounced it "Yucky" so no one else tried it.

The defensive mechanism of smell and taste varies among the population. There is a molecule in many vegetables that renders them horrid tasting to a large portion of the population. This is a defensive mechanism developed through evolution to protect the plants from being eaten. You mentioned blueberries in your post. My wife loves them, so there are around much of the time, but I don't eat them because I cannot taste them.

Hyenas and vultures have evolved stomach acids strong enough to destroy putrescence bacteria.

Why haven't we all?

And vultures piss all over their legs to kill the bacteria that get on them while feeding.

That would add a nice touch to the end of a Thanksgiving dinner.

Uncle Frank, my parents stopped inviting him.  I wondered why.

Poor Uncle Frank. Maybe he just has ancient DNA.

Your question is a good one. It's possible that at some point in our distant past, some of our ancestral species could ingest carrion. But as we lost the need for carrion, the ability to ingest it may also have been lost.

For example, consider the squirrel and the rattlesnake.

There must be some evolutionary disadvantage to being a carrion-eater which I cannot pinpoint. Let's see, what do vultures and hyenas have in common? Extreme bad looks?

Incidentally, I actually know why my parents stopped inviting Uncle Frank (who was real). It was because they didn't approve of his place of employment.

Apparently "extreme bad looks" are not a hindrance to procreation. Vultures and hyenas are still around, so they must be getting laid. And so is Ugly Fred, an old friend who deserves the nickname but has been married at least five or six times; the only one I met was a knockout. Of course, she did wind up shooting him in the throat, but I don't know if that was about his looks or his girlfriend.

If you try to assign a purpose to evolution, you will be continually confused because there is none. There is no end to the physiological problems that the human species has that, presumably, could have been resolved by evolution but were not.

Caught some of your little friends just chilling yesterday. (Yeah. I know I need a longer lens.)

Not fast enough with my camera.

I just walked out on the back deck for a minute, and a vulture flew by quite close - maybe twenty or thirty feet away - and a small bird was hunkered down on the top of its left wing. I came in and got my camera, but the guy never got close again and eventually flew away to the other side of the valley.

Kind of cool.