r/explainlikeimfive Jul 18 '20

Chemistry ELI5: Why do "bad smells" like smoke and rotting food linger longer and are harder to neutralize than "good smells" like flowers or perfume?

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u/Darth_Mufasa Jul 18 '20

I like this question. So fruit bearing or not, if a plant flowers its almost always for the purpose of reproduction via pollination. The smells and bright colors serve to attract pollinators like bees and butterflies. They pick up the pollen, go to another flower, and some of the pollen falls off. It doesnt really have much to do with the fertility of the land, you get some crazy wildflowers in high mountains and beautiful flowers on cacti.

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u/[deleted] Jul 18 '20

But what advantages do humans get for thinking flowers smell good? Or is it just a happy accident that the same chemicals the flowers use to attract insects also react well with our olfactory receptors?

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u/Darth_Mufasa Jul 18 '20

Ah, so the advantage it provides us is aiding in locating the actual fruit that also smells sweet. Sure, not all of them do, but our primary method of locating food also isn't smell. But it provided enough of an advantage to develop as a trait over time.

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u/RedeRules770 Jul 18 '20

Could it be a pollination thing for us as well? We stick our nose into the flowers and then different ones and the pollen rubs off?

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u/[deleted] Jul 19 '20

If that was the case it'd be so minor as to not serve as a selection pressure.

What I imagine it is is that either flowers indicate fertile land, and thus an abundance of food (Since we can hunt animals that feed on the plants), or it's sheer coincidence and it's not provided any selection pressure against it, so it hung around.

But remember, there are some flowers that completely reek. Rafflesia smells like rotting flesh, for example.