In the forests of Central and South America, a peculiar plant grows. Its white flowers give way to brightly-colored fruits, within which lies a fiery fury. This fruit, as we know it today, is the chili pepper, Capsicum annuum, of which there exist many cultivars. Perhaps one of the most prolific agricultural exports of Latin America, the chili pepper populates cuisines all over the world and provides a unique sensory experience separate from taste or smell—that of burning pain.
From an outsider’s perspective, it might seem strange that we humans seek to eat something that causes us pain; in nearly every other aspect of our lives, we aim to reduce discomfort. This behavior of ours is unique as well, shared with just one other animal: the tree shrew. Might it be masochism bringing us to do this? And why do some people love spicy food while others balk at the mere suggestion of it?
The hows of heat
Like the tomato, chili peppers belong to the Solanaceae or nightshade family of flowering plants, all containing compounds called alkaloids. Nightshades use these alkaloids—many of which are toxins or irritants—to deter insects and other animals from consuming them. Chili peppers, in particular, contain the alkaloid capsaicin, which produces the painful burning sensation that we recognize as spiciness.
Capsaicin can do this because it activates the TRPV1 ion channels in our bodies, which are only typically activated by high temperatures and low pH levels. Thus, whenever we eat spicy food, its capsaicin content activates the TRPV1 receptors in our mouths, sending pain signals to our body and brain through our nervous system. This is also why the pain from capsaicin feels like that from hot objects: it is, quite literally, activating the receptors only typically activated by high temperatures.
According to Dr. Charles Spence, a professor at the University of Oxford, sensitivity to capsaicin is a uniquely mammalian trait—birds, for example, are unbothered when eating the seeds of chili peppers. This is because non-mammals have a different version of the TRPV1 receptor that either isn’t activated by capsaicin or is activated by it poorly. Interestingly, while birds and other non-mammalian animals are insensitive to capsaicin, they can taste other spicy organic compounds, such as the allyl isothiocyanate in wasabi or piperine in black pepper.
In the aftermath of eating spicy food, our bodies try to quell the pain by releasing endorphins and dopamine—neurotransmitters related to pain relief and pleasure, respectively. The mix of these two in our bodies produces a sense of relief or euphoria, which is possibly why many people love spicy food. They may not necessarily like the pain but rather the euphoria that comes afterward.
A polarizing flavor
Unlike sweet and salty flavors, spiciness is associated with the trigeminal nerve triggering a painful—yet to some, pleasurable—sensation. This is not only experienced through tasting alone, but also when particles of chili or even pepper, cinnamon, and menthol products—enter our noses and eyes.
Needless to say, spiciness is an acquired taste, and building tolerance to its effects may be both physiological and psychological. While our taste buds do adapt to the food we consume regularly, some may chase the endorphin rush that comes with consuming a painful flavor. However, we are all born with a natural aversion to potentially harmful foods signaled by bitterness and spiciness. Over time, some can learn to like these flavors.
Other senses also play a role in how we perceive spiciness. Spence notes that research in Taiwan and California has shown that individuals psychologically perceive food to be spicier with the presence of red on the dish, provided that it was moderately spicy, to begin with. Music can also affect our sense of taste—this is called sonic seasoning. According to Spence, “when [restaurant customers] heard the spicy soundtrack that had been created based on our research, people rated that mango salad as spicier than if they were listening to something else or nothing.” The spicy soundtrack was described to be “high tempo, energetic, with lots of transitions.”
There are still plenty of factors that explain why some people are drawn to spice, and others are apprehensive. For one, there is a cultural aspect to this preference. “It might be the most important [factor] in our chili consumption behavior,” Spence notes. For instance, in Mexico, people are exposed to chili very early on in life as it is greatly ingrained in their cuisine. On the other hand, people who grew up in North America or the United Kingdom may treat spice as simply an additive to their meals.
The way that cultures view and use spiciness does vary, and there are climatic reasons for it too. According to Spence, since spices like chili are used as antimicrobial agents that help kill bacteria in food before refrigeration, spices have more use in warmer countries. As such, Thai dishes have 10 spices on average, while food from Norway—a country that can reach temperatures of 1.9 degrees Celsius—only has an average of 1.8 spices in their dishes.
Others may argue that one’s spice tolerance is more psychological than biological; tolerance is built up over time through exposure and the desire to handle more extreme forms of spiciness. “It’s not like some babies at birth love a chili,” Spence explains. “It’s something that we all have to learn to adapt to.” Moreover, one may try to keep pushing the limits of their spice tolerance because of the endorphin hit gained by swallowing something that is just on the brink of being painful.
Some personalities may also be inclined to enjoy spice as part of their love for sensation-seeking. These are the kind of people that are likely to go bungee jumping or skydiving—they just want to get that extreme sensation to hit any of their senses.
With so many different things influencing one’s view of spiciness, there is no way to pinpoint exactly why some love it so much while others simply cannot stand it. Biology, psychology, and culture all have a role to play in one’s feelings regarding spiciness and the varying reactions to that sensation. For some, pain is pleasure, and that is why they keep seeking that stinging sensation from spice.