The chemicals in hot peppers that cause the burning sensation may protect them from animals so they get eaten by birds.
Any plant, whether it is a shrub like a pepper, a tree or an herb, that has bright red or orange fruit with a number of small seeds in it, and in which the fruit does not fall to pieces, but is removed whole, is almost always taken by fruit-eating birds.
The seeds of those plants are adapted to being dispersed by birds, and many peppers, especially wild ones, are very attractive to birds.
Therefore, scientists suspect that the compounds in hot peppers that cause the burning sensation serve to keep other animals from eating the pepper fruits and to preserve them for the birds.
One example that grows wild in the southwestern United States and Mexico is in fact called bird pepper, or Capsicum annuum aviculare, because birds greedily devour the fruits.
In wild peppers like this one, the birds seem to have no aversion to eating the fruits and are not affected by the substance that causes horrendous burning in us.
However, the jalapeno pepper and practically all the others in the food market are not wild varieties, but have been bred for different colors, shapes and degrees of hotness, or simply for larger fruits.
The ones the birds favor have many small fruits on a plant, each about the size of a pea.