Why did chillis evolve to become spicy?

Mystery Hour Question

Is there an evolutionary benefit in chillis being hot?
David, Reading

Answer

**Definitive**

Name: Professor Hal
Qualification: Professor of Public Understanding of Science, University of Brighton
Answer: Chillis evolved so that mammals won’t eat them. Seeds get destroyed in mammalian stomachs due to their acidity level, and so mammals will avoid something that is unpleasantly hot. Whereas bird stomachs don't break down the seeds, so birds will eat chillis, and disperse the seeds. So chillis are evolutionary programmed to be attractive to birds, but not to mammals.