How chili peppers evolved to be so hot, explained while eating one

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I had to answer almost this same question on my midterm exam in undergraduate biopsychology 20+ years ago. I think I was expected to give the answer here (not while eating a pepper though). I didn’t buy this explanation (and still don’t). I said the peppers are hot because we have selectively bred them to be hotter, because we for some reason enjoy the pain. I got like 1/5 points on my answer, and as you can tell, I’m still upset. This is one of the reasons even people who strongly support evolution as a concept criticize its application in many particular cases as a scientific account–the stories told using evolution to explain a particular thing are often not falsifiable, not even testable, and not mutually exclusive with other accounts.

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It’s probably due to wearing nothing but socks on stage


Hey, nobody ever said scientists had to be smart. Just methodical.


Q: How does one quantify the mass of a red hot chili pepper?

A: Give it a weigh, give it a weigh, give it a weigh now.


You aren’t wrong, but your answer was incomplete.

Chiltepins are hot (hotter than habeneros) and humans didn’t selectively bred them, except to create other capsicum annuum peppers of various heats (including bell peppers). There are other wild chillies that aren’t grown commercially that are also a similar heat.

The human bred super hot varieties came very recently, no one really cared until Guinness World Records became interested.


Well, there’s a difference between “Why did chili peppers evolve heat?” and “Why are chili peppers SO hot?” Your answer to the second question makes sense. We liked the heat, so we bred hotter and hotter chilis.

This is an explanation of the first question. Natural selection favored dispersal by birds over mammals (and apparently protection from insects and mold), caused by mutations that created capsaicinoids. That seems a likelier explanation to me than humans somehow breeding capsaicin production into peppers that never had it before.


The hotter the better but not always. My threshold is a sliding scale that I can’t explain. When I was a kid I used to brag that I could eat any chili there was. This was I think before habaneros were a well known thing even in Colorado where I lived. They started selling them and my friends bought one to “trick” me. I popped the whole thing in my mouth and hoo-boy was I laughed at. I can still handle it and use them all the time. But here’s another aspect: humans use their hands with their nether regions and it might be after you’ve chopped one up and you think you’ve washed your hands well enough before you use the restroom. Not good enough usually.

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Anthony Kiedis says “that’s what she said”

I toss hot peppers in a blender then spray some plants to battle insects. It works pretty good, better than plain water for sure.

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