Bell peppers originated in Mexico, where their wild ancestor still grows today. The species Capsicum annuum was domesticated at least 10,000 years ago in central-east and northeastern Mexico, making it one of the oldest cultivated crops in the Americas. What we now call the bell pepper is simply a later variety of that same species, bred over centuries to be larger, sweeter, and completely free of heat.
The Wild Ancestor in Mexico
The wild predecessor of every bell pepper is a small perennial shrub called Capsicum annuum var. glabriusculum. It still grows across parts of Mexico and produces tiny, pea-sized, globe-shaped fruits that point upward from the stem. These little fruits are spicy, nothing like the large, blocky sweet peppers in grocery stores today, but they carry the same core genetics.
Research published in the Proceedings of the National Academy of Sciences used multiple lines of evidence, including ecological modeling, genetics, linguistics, and archaeology, to pinpoint the most likely zone of domestication. The consensus points to central-east Mexico and northeastern Mexico, placing chili pepper alongside maize and common beans as part of a multiregional crop origin story across the country. The earliest archaeological samples from this period are mostly seeds of the wild form, suggesting people gathered and ate wild peppers for a long time before full domestication took hold.
10,000 Years of Cultivation
Peppers weren’t domesticated just once. Five separate Capsicum species were independently domesticated across Central and South America beginning at least 10,000 years ago, with some species possibly undergoing multiple domestication events in the same region. For Capsicum annuum specifically, ecological niche modeling shows that conditions in Mexico were suitable for the wild ancestor around 10,000 years before present, aligning with the window when early peoples in the region were transitioning from foraging to farming.
By roughly 2500 BC, sweet pepper varieties were already being grown in Mexico. That’s thousands of years before Europeans arrived, meaning indigenous farmers had already selected for traits like larger fruit size and milder flavor long before the concept of formal plant breeding existed.
How Bell Peppers Lost Their Heat
Bell peppers belong to the exact same species as jalapeños, serranos, and cayennes. The difference is a single gene. The gene responsible for producing capsaicin, the compound that makes peppers burn, is called Pun1, located on chromosome 2. In bell peppers, a large chunk of DNA (about 2,500 base pairs) is deleted from this gene, completely disabling it. Without a functioning copy, the pepper can’t produce capsaicin at all.
What’s striking is that when researchers examined sweet pepper varieties from around the world, nearly all of them carried the identical mutation. This suggests that the loss of heat likely happened once, in a single ancestral sweet pepper plant, and every modern bell pepper traces its mildness back to that one genetic event. A second gene on chromosome 3 can also knock out heat through a different pathway, blocking the production of a key ingredient needed to build capsaicin. A Thai variety called CH-19 Sweet, discovered in 1989, was the first known pepper to use this alternative route to sweetness.
Columbus and the Name “Pepper”
The word “pepper” for Capsicum fruits is a case of mistaken identity that stuck. When Columbus encountered pungent chili peppers in the Caribbean in the 1490s, he was looking for a western route to the spice-rich Indies. Black pepper (Piper nigrum) was one of the most valuable traded spices in Europe at the time. Columbus called the new spice “pimiento,” the Spanish word for pepper, because of the similar burning sensation. The two plants are completely unrelated, but the name never got corrected.
How Peppers Spread Worldwide
After Columbus brought peppers back to Spain, they first took root in the Iberian Peninsula. From there, trade routes carried them across the Mediterranean Basin and eventually to Africa, India, and China. The Portuguese played a particularly important role in this global spread, shipping peppers from Brazil along their established trade routes to colonies and trading posts in Africa and Asia.
There’s an interesting wrinkle in this story. Researchers have proposed that the Portuguese likely avoided introducing pungent peppers into European markets, since hot Capsicum peppers would have competed directly with black pepper, a cornerstone of the Portuguese spice trade from the Far East. That may explain why sweet and mild pepper varieties gained more traction in European cooking, while the hotter types flourished in tropical climates across Asia and Africa, where they were adopted with extraordinary speed. Within just a century of contact, chili peppers had become so deeply integrated into cuisines from India to Thailand to West Africa that many people assumed they were native crops.
Today, China is the world’s largest producer of peppers, and bell peppers are grown commercially on every inhabited continent. But every one of them traces back to a wild shrub with tiny, fiery fruits growing in the hills of Mexico.