thinking about. the commonly accepted reason why chilis evolved to produce capsaicin in the first place
basically, mammals (humans included) have receptors in various areas that that chemical binds to, producing a burning sensation, whereas avians lack these receptors. so mammals that eat it quickly figure out not to do that, but birds are fine. and birds, they fly around and generally travel further before the seeds from the chili finish passing through their digestive tract and end up wherever they'll try to grow. so by spreading them further out via birds there's less likelihood that a plant will have to compete for resources with its own offspring
