It is not an exaggeration to say that chilli peppers and spicy food are available on pretty much every street in China.The pungent, heat-infused foodstuff is so ubiquitous people joke that if a person does not indulge, they will starve, or at best lose friends, because eating spicy things fosters social bonding.However, the popular ingredient has only been around in China for a relatively short time.It first entered the country 400 years ago and people have been eating it for about three...