Why some like it hot: The science of spiciness

Why chilli burns?
Spiciness is a burning sensation caused by capsaicin in food. When we eat spicy food, capsaicin stimulates receptors in our mouth called TRPV1 receptors and triggers a reaction. The purpose of TRPV1 receptors is thermoreception — the detection of heat. This means they are supposed to deter us from consuming food that burns.
When TRPV1 receptors are activated by capsaicin, the sensation we experience is linked to the feeling of encountering something hot, near the boiling point of water. However, this pain is nothing more than an illusory side effect of our confused neural receptors — there is nothing actually “hot” about spicy food.
Not all chillies are eequa
Different degrees of spiciness exist according to the chilli you are eating. In 1912, pharmacist Wilbur Scoville created a scale to measure the pungency (spiciness) of chilli peppers. This scale, measured in Scoville Heat Units (SHU), is based on the capsaicinoid sensitivity experienced by people eating hot chillies. On the standard Scoville heat scale, bell peppers (SHU=0) are on the bottom. Jalapeno peppers can range anywhere from 2,500 to 10,000. By comparison, Tabasco peppers are between 25,000 to 50,000 units, and habanero chilli ranges between 100,000 to 350,000. The world’s hottest pepper — the Carolina Reaper — goes all the way up to 2.2 million units. Bear spray — two per cent capsaicin — is advertised at 3.3 million units, and pure capsaicin hits 16 million at the top of the Scoville scale.
Human pleasure Psychologist Paul Bloom writes: “Philosophers have often looked for the defining feature of humans — language, rationality, culture and so on. I’d stick with this: Man is the only animal that likes Tabasco sauce.” Bloom was right. There is not a single animal that enjoys hot pepper, but we are not the only animal species eating chillies. Mammals, like mice and squirrels, share the same spicy food receptors humans have, and they tend to avoid hot peppers as food sources.
Birds eat hot peppers — but they can’t actually feel the heat. Birds have different receptors from humans and are biologically unable to register the effects of capsaicin. Explaining the reason for the evolution of capsaicin is not that easy. Some argue that it is an adaptation to select birds to eat chilli fruits. Birds don’t chew or digestseeds like rodents, and they transport them far away.
Other studies have suggested that capsaicin is also an effective deterrent against the attack of parasitic fungi, and the heat sensation in mammals is a side effect. Some experts argue that humans like chillies because they are good for us. They have some beneficial effects on human health. They reduce blood pressure and may have some antimicrobial effects. The pain of chillies can even overwhelm and help manage other pains. Another hypothesis can be described as benign masochism. Psychologist Paul Rozin suggests that there’s a sort of thrill similar to the fun of riding a roller coaster. In an interview, he explained: “Mind over body. My body thinks I’m in trouble, but I know I’m not.”