The Science Behind Spice - Why We Love Heat
- Anjali Carl
- Nov 10
- 3 min read
Capsaicin evolved in chili peppers out of necessity. Initially, animals would crush the seeds and destroy them, preventing the plant from . So plants evolved to develop capsaicin which made animals sick when they ate it. However, birds are immune to the spice because their pain receptors don’t register capsaicin. Birds would swallow the seeds whole and then scatter the seeds. It’s a brilliant evolutionary strategy.
And then there’s us humans. We are not immune to capsaicin like birds and our bodies give us all sorts of signals to avoid it. But throughout history, we have managed to ignore those signals, override our pain responses and now enjoy the burn. We are the only species to actively seek out something we are evolutionary primed to avoid, and we have turned it into a delicacy. How did that happen?
The answer starts with history and geography. Thousands of years ago, in hot climates such as India, Central America, Southeast Asia, populations had trouble with food spoiling quickly. It was the time before refrigerators and so preserving meat and produce was crucial to survival. Someone discovered chili peppers had powerful antimicrobial and antifungal properties due to capsaicin. This allowed families to eat when food was scarce, ensuring their survival.
Over generations, spice became an everyday additive. Parents began feeding spice to their children and those kids grew up with their pain receptors desensitized to capsaicin. Spice evolved from being purely for survival and is now woven into the community’s cultural identity.
This is why spice and spice tolerance is so different in different parts of the world. In Mexico, it’s smoky chilies and salsas. In India, spice is created through layers of chili, ginger and peppers. If you grew up eating spicy food, whether in Thailand or Korea, your taste receptors adapt though a process called desensitization.
So what’s the science of how we detect spice? We don’t actually taste spice because there are no spice taste receptors. Capsaicin binds to receptors on your sensory nerves called TRPV1 (transient receptor potential vanilloid 1). TRPV1’s job is to detect heat (43 degrees C), pain (through capsaicin), and acidity( low pH). Once it is activated, it lets calcium ions enter the cell and sets up the signal to the brain that the body is in pain.
Once that signal is sent, your body responds as if you really were in pain, resulting in watery eyes, sweating, and a burning sensation. But what’s interesting is that the body also releases endorphins and dopamine, which are the chemicals responsible for pleasure and reward. These are the same chemicals that are released during a “runner’s high”. So the initial pain response fades into a feeling of euphoria. Suddenly, that next bite doesn’t seem so bad and we go for it.
Over time, our brains and bodies adapt to the spice which is why we can gradually eat spicier foods. If something gets too spicy, dairy products like milk and yogurt can help neutralize the sensation. Dairy contains a protein called casein which can break down capsaicin and remove the heat sensation.
The next time you eat something spicy, you will understand the science behind the sensation. It’s about the food, culture and chemistry and how our mind and body work so closely together.
Anjali Carl is a junior at Cedar Park High School in Cedar Park, Texas.They have been excited about food science since making ice cream in a third-grade science class, and now enjoys baking and recipe development. Through their Girl Scout Gold Award project, they created two cookbooks focused on reducing food waste for food pantries and college students. They plan to study food science and eventually become an ice cream chemist.
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