Hot chilli peppers have been credited with helping to lose weight, inducing labour and relieving pain. But until Wilbur Scoville, there was no objective way of measuring how hot chillies really are. Scoville, an American chemist born 151 years ago on Friday, is responsible for the "Scoville organoleptic test", a scale of "hotness" that has been the definitive rating of how spicy a chilli is for more than 100 years. On his birthday, Google has saluted Scoville with an interactive Doodle that asks visitors to assist his experiments by cooling the chillies' heat.