The science of spiciness - Rose Eveleth

Why does your mouth feel like it's on fire

when you eat a spicy pepper?

And how do you soothe the burn?

Why does wasabi make your eyes water?

And how spicy is the spiciest spice?

Let's back up a bit.

First, what is spiciness?

Even though we often say that something tastes spicy,

it's not actually a taste,

like sweet or salty or sour.

Instead, what's really happening

is that certain compounds in spicy foods

activate the type of sensory neurons

called polymodal nociceptors.

You have these all over your body,

including your mouth and nose,

and they're the same receptors

that are activated by extreme heat.

So, when you eat a chili pepper,

your mouth feels like it's burning

because your brain actually thinks it's burning.

The opposite happens when you eat something

with menthol in it.

The cool, minty compound

is activating your cold receptors.

When these heat-sensitive receptors are activated,

your body thinks it's in contact

with a dangerous heat source

and reacts accordingly.

This is why you start to sweat,

and your heart starts beating faster.

The peppers have elicited

the same fight-or-flight response

with which your body reacts to most threats.

But you may have noticed that

not all spicy foods are spicy in the same way.

And the difference lies in the types of compounds involved.

The capsaicin and piperine,

found in black pepper and chili peppers,

are made up of larger, heavier molecules

called alkylamides,

and those mostly stay in your mouth.

Mustard, horseradish, and wasabi

are made up of smaller molecules,

called isothiocyanates,

that easily float up into your sinuses.

This is why chili peppers burn your mouth,

and wasabi burns your nose.

The standard measure of a food's spiciness

is its rating on the Scoville scale,

which measures how much its capsaicin content can be diluted

before the heat is no longer detectable to humans.

A sweet bell pepper gets 0 Scoville heat units,

while Tabasco sauce clocks in between 1,200-2,400 units.

The race to create the hottest pepper

is a constant battle,

but two peppers generally come out on top:

The Trinidad Moruga Scorpion

and the Carolina Reaper.

These peppers measure

between 1.5 and 2 million Scoville heat units,

which is about half the units found in pepper spray.

So, why would anyone want to eat something

that causes such high levels of pain?

Nobody really knows when or why

humans started eating hot peppers.

Archaeologists have found spices like mustard

along with human artifacts

dating as far back as 23,000 years ago.

But they don't know whether the spices were used

for food or medication or just decoration.

More recently, a 6,000 year old crockpot,

lined with charred fish and meat,

also contained mustard.

One theory says that humans

starting adding spices to food

to kill off bacteria.

And some studies show that spice developed

mostly in warmer climates

where microbes also happen to be more prevalent.

But why we continue to subject ourselves

to spicy food today

is still a bit of a mystery.

For some people,

eating spicy food

is like riding rollercoasters;

they enjoy the ensuing thrill,

even if the immediate sensation is unpleasant.

Some studies have even shown

that those who like to eat hot stuff

are more likely to enjoy other adrenaline-rich activities,

like gambling.

The taste for spicy food

may even be genetic.

And if you're thinking about training a bit,

to up your tolerance for spice,

know this:

According to some studies,

the pain doesn't get any better.

You just get tougher.

In fact, researchers have found

that people who like to eat spicy foods

don't rate the burn any less painful

than those who don't.

They just seem to like the pain more.

So, torment your heat receptors all you want,

but remember, when it comes to spicy food,

you're going to get burned.