If you ask anyone why chilli peppers are hot you will usually be greeted with a long pause and a scratch of the head. Having hot fruit, and seeds in particular is rather counter intuitive from a evolutionary perspective.
It is generally accepted that plants produce nice tasty colorful fruit to attract and encourage animals to eat them and spread their seeds allowing the plant species to spread. So why then do chillie plants encase their seeds in capsaicin (the chemical that produces the heat in peppers) that will put off all but the most determined or hungry of animals?
Well researches from the National Academy of Sciences think they have finally solved the mystery.
Firstly it should be noted that the various species of chillie plants out there have been able to survive and spread thanks to the inability of most species of birds to detect the heat present in capsaicin. Secondly it seems that capsaicin is produced to help plants prevent the fungus Fusarium. Fusarium is the biggest cause of seed mortality in the wild and therfore the heat produced by chili plants is simple their evolutionary way to protect their seeds.