I believe spicy foods kill certain types of gut parasites.
So at some point in our evolutionary history some weirdo who liked a bit of spice was born, burned the parasites out of their gut, and then with their increased health and no calories being stolen natural selection did the rest.
Us humans are just a pawn in the chili plants' game of spreading all over the world.
Initially, capsaicin was produced to prevent mammals from eating the fruit (peppers) and instead encourage birds to spread seeds over a wider area (which is why they are brightly coloured to attract birds). Now that humans can travel greater distances than birds, the plants have switched strategies (or at least we've deliberately grown flavourful varieties everywhere we can).
> Several alternative hypotheses were considered-that spices provide macronutrients, disguise the taste and smell of spoiled foods, or increase perspiration and thus evaporative cooling; it also is conceivable that spice use provides no benefits. However, none of these four alternatives was well supported by our data. The proximate reason spices are used obviously is to enhance food palatability.
> But the ultimate reason is most likely that spices help cleanse foods of pathogens and thereby contribute to the health, longevity and reproductive success of people who find their flavors enjoyable.
You are conflating 'clean' with 'sanitary'. You may have washed the dirt and oils off of your skin and hair but your body itself contains, produces, and provides habitats for all manner of organisms, cells, and biological and chemical substances that slough off onto anything around it. Take sterile cotton swab and rub it on your 'clean' post-shower butthole and grow a culture from it and tell me how 'clean' it really is.
The bathroom is a place filled with moisture. If you’re taking two showers a day the towel may spend most of the day wet. It’s a good environmental for mold.
But I also think these rituals are about being pure. Washing off the struggles of the day.
Why did they become popular recently? Pain causes the release of endorphins, overall making you feel good. A similar concept as a runners high, except achievable watching TV on the couch.
Their original spread was likely for the same reason as most other spices, it could be used as a preservative by masking the taste of semi-rotten food.
Small amounts can cause a good amount of pain for those who aren't used to it. I remember putting crushed red pepper on a piece of pizza as a child and finding it unbearably hot.
Why did spicy foods become so popular when the first sensation they cause is pain?