How come certain animals aren’t as repulsed by some really disgusting odors or smells?

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Or are they affected but they have a higher tolerance before the smell overwhelms them?

In: Biology

Smells are just chemicals in the air. Whether you find them absolutely repugnant or delicious is down to how your brain has evolved to interpret that signal.

Humans have evolved to find some specific scents like the sulfurous gases of rotting meat extremely repulsive, to protect us from the hazards of eating spoiled food.

Scavengers with lead stomachs that actually prefer to eat this disgustingly extra-tenderized meat don’t find the scent bad – they’re drawn to it. Many even have noses many times more sensitive than ours to track the sweet smell of roadkill from miles away.

You even get bizarre cases of flowers mimicking the stench of death to attract flies as pollinators instead of bees.

One man’s trash is another’s treasure- or in this case, one species biohazard is another’s lunch. You are repulsed by things as an evolutionary trait. Eating feces is a biohazard to you, but it’s a great food source for things that can digest it- like flies or beetles. Rotting meat is full of bacteria that will make you sick, but a Turkey vulture can handle no problem- what’s disgusting to you is the sweet smell of sustenance to them

They may have different smell or taste receptors.

For example, apparently birds don’t have a very strong sense of smell or taste- they can only detect very strong, almost noxious, odors. For this reason we put a special hot sauce on birdseed- squirrels actually flinch when they come near it (because they’re able to smell it more strongly) but the birds flock to it (it probably reads as spicy as a normal taco bell taco to them bc they can’t smell or taste much).

And what smells bad to one animal (like humans) might be interpreted by another animal’s brain (like dogs)in a different way.

I did a literature review in college on the science of disgust. There have been studies on very young children where the children learned disgust behavior from their mothers. They were asked to drink from a glass that had previously had a bug in it, and only did so if their mothers did it first. Revulsion, very similar to disgust, appears to be something we’re born with. If you feel a violent urge to barf when you smell or see someone else puke, or see maggots crawling on a dead animal – that is most likely evolutionary. Some ancestor WAY down your family tree was probably saved by regurgitating when it became apparent that nearby food could be spoiled, or that someone in their clan was sick from spoiled food.
Your dog, on the other hand, evolved to eat some pretty gross rotten stuff and be fine with it. His species never needed to evolve the trait of avoidance to dead or sick things the same way we do. And most smells we find disgusting have some properties in common with rotting and unsafe things.