Chili peppers are not vegetables but berries, a botanical classification that has shaped their history and culinary dominance for millennia. These shiny, brightly colored fruits of the genus Capsicum originated in modern-day Peru and Bolivia, becoming a staple in human diets as early as 7,500 BC. They were among the first self-pollinating crops cultivated in the Americas, with evidence of cultivation in east-central Mexico dating back 6,000 years. Peru remains the center of diversification for these plants, hosting the highest diversity of cultivated Capsicum species, while Bolivia holds the largest diversity of wild Capsicum peppers, including unique landraces like ulupicas and arivivis. The plant's ability to thrive in diverse climates, from the Amazon to the highlands, allowed it to become one of the oldest and most widely distributed crops in the world before European contact.
The Columbian Exchange
When Christopher Columbus and his crew reached the Caribbean, they were the first Europeans to encounter Capsicum fruits, mistaking them for the black pepper they knew from Asia. They called them peppers because, like Piper nigrum, they possessed a hot spicy taste unlike any other food. Chilies were first brought back to Europe by the Spanish, who financed Columbus's voyages, at the start of the large-scale interchange of plants and culture between the New World and the Old World known as the Columbian exchange. Chilies appeared in Spanish records by 1493, and by the mid-1500s, they had become a common garden plant in Spain. Their rapid spread continued, appearing in Italy by 1526, in Germany by 1543, and in the Balkans by 1569, where they were eventually processed into paprika. The Portuguese introduced them to Africa and Arabia, and then to their colonies and trading posts in Asia, including Goa, Sri Lanka, and Malacca, while the Spanish brought them to the Philippines, from where they spread to Melanesia and Micronesia via the Manila galleons.The Science of Heat
The substances that give chili peppers their pungency are capsaicin and several related chemicals collectively called capsaicinoids. Pure capsaicin is a hydrophobic, colorless, odorless, and crystalline-to-waxy solid at room temperature. The quantity of capsaicin varies by variety and depends on growing conditions, with water-stressed peppers usually producing stronger fruits. When peppers are consumed by mammals, capsaicin binds with pain receptors in the mouth and throat, potentially evoking pain via spinal relays to the brainstem and thalamus. However, birds are unable to perceive the hotness and can eat some of the hottest peppers, which suggests the plant produces capsaicin as a defense against mammalian predators. The intensity of the heat is commonly reported in Scoville heat units, invented by American pharmacist Wilbur Scoville in 1912. Historically, it was a measure of the dilution of an amount of chili extract added to sugar syrup before its heat becomes undetectable to a panel of tasters. Since the 1980s, spice heat has been assessed quantitatively by high-performance liquid chromatography, which measures the concentration of heat-producing capsaicinoids.