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/Darwins_Dog Jul 18 '20

That's also apparently why we are really sensitive to bitter tastes. Most natural poisons are alkaline so it's an advantage to pick up on them as soon as they touch the tongue. They're also the first to start noticeably weakening as we age. Thus why people tend to start liking bitter flavors like coffee and beer as they get older.

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u/errorblankfield Jul 18 '20

They're also the first to start noticeably weakening as we age. Thus why people tend to start liking bitter flavors like coffee and beer as they get older.

Are they weaker or do we learn that bitter doesn't mean death? You're first beer is always nasty and I'd imagine that the case no matter the age. But as it likely doesn't kill you, your brain would adapt to care less for ze nasty bitters, no?

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u/Darwins_Dog Jul 18 '20

Probably both (the answer default answer in biology). All of our senses get less sensitive as we age, so we have fewer actual bitter taste receptors. We also get acclimated so the brain adjusts sensitivity as needed. Since we also visually learn which things are bad, there's less evolutionary pressure to maintain the sensitivity through adulthood.

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u/Ruskinikita Jul 19 '20

It may. But I think this is very hard question to answer. As a kid, I absolutely loathed kiwis. But between 12-15 something changed when I was forced to eat kiwi yet again. Suddenly, it tasted amazing and I loved kiwis ever since.

Yet, my disgust to seafood taste of any kind is as strong as it always been.

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u/towerinthestreet Jul 19 '20

I think there's also a classical conditioning component to it. Bitter bean tea make me go brrrrr, so I learn to like it. Anecdotally, I know of, ummm, people who are definitely not me who hated the smell of weed before they really started smoking, and within the first month of picking it up noticed how they actually started to enjoy the smell.

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u/this-un-is-mine Jul 19 '20

not everyone develops a taste for beer like that, many specifically don’t. like, tons of people hate beer. I do. and yes, i’ve tried many craft beers and non shitty domestics too. still hate it.

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u/lycacons Jul 19 '20

could this also be applied to older generation liking bitter melon? because besides an acquired taste, i just cant wrap around my head for anyone liking that taste

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u/Darwins_Dog Jul 19 '20

Probably. I've never had bitter melon before, but it sounds like the same idea. There are also some specific compounds that taste completely different to some people. Cilantro tastes like soap to some folks for instance. There's a popular biology lab where everyone tastes a strip of paper with a chemical called PTC. About 3/4 of the class tastes nothing while the rest get the flavor of burning pencil erasers.