Listen and Subscribe
Podcast Transcript
For thousands of years, humans in the Americas have cultivated an extremely hot plant.
When it was transferred to the Old World, it transformed cuisines, inspired scientific measurements, and made some meals much, much, much hotter.
Its story stretches from the ancient Americas to kitchens on almost every continent.
Learn more about the surprisingly hot history of peppers on this episode of Everything Everywhere Daily.
Before we get into peppers, we have to clarify what exactly we are talking about because the word “pepper” applies to several different types of plants.
The word pepper originally applied to spices such as black pepper and long pepper. Likewise, Sichuan peppers from China are another wholly unrelated plant that carries the same name. These plants are not related to the subject of this episode.
The topic of this episode will be Capsicum peppers, or members of the genus Capsicum. What all these plants mostly have in common is the production of the chemical capsaicin. (cap-say-a-sin).
True Capsicum peppers are members of the nightshade family, Solanaceae, making them relatives of tomatoes, potatoes, eggplants, tobacco, and petunias. Botanically, the fruit of a pepper plant is actually a berry, although nobody would normally call it such.
The genus Capsicum is entirely native to the Americas, with its natural range extending from Mexico through Central America and the Caribbean into much of tropical South America.
When Europeans first arrived, the only real thing they had to compare these hot, spicy plants to was black pepper, so they dubbed them peppers, and the name stuck.
The American origins of pepper plants are surprising to many people, given how important they have become in cuisines across India, Africa, Thailand, and parts of China. Yet all of these places adopted peppers only after they were brought back across the Atlantic and spread through trade routes in the Indian Ocean.
Another important distinction is that between chilies and peppers. Pepper is the broader classification that applies to all Capsicum plants. The term chili refers to the category of hot pepper plants that produce capsaicin.
Non-chili peppers are usually referred to as bell peppers. Bell peppers have essentially no capsaicin. They carry a genetic mutation that prevents them from producing meaningful amounts of it.
Interestingly, bell peppers aren’t really a fundamentally different type of plant. They’re essentially non-spicy chili peppers that have been selectively bred for large, sweet fruits.
Green, yellow, orange, and red bell peppers are usually different varieties or stages of ripeness, with red peppers generally being sweeter because they’ve been allowed to mature longer.
Also interestingly, breeders have done the same thing with normally hot pepper types. New Mexico State University has, for example, developed habanero-type peppers that retain the characteristic habanero aroma while producing little or no heat.
Wild Capsicum plants probably originated in tropical South America and diversified throughout Central and South America over millions of years. Humans encountered these plants thousands of years ago and independently domesticated several different species in different parts of the Americas.
The most important domesticated species today is Capsicum annuum. Despite the name annuum, meaning annual, the plant can actually live for several years in tropical climates.
Genetic, archaeological, linguistic, and ecological evidence indicates that its principal domestication took place in Mexico, probably somewhere in central-eastern or northeastern Mexico.
Humans had been using wild peppers long before the fully domesticated varieties appeared. Domestication gradually transformed small wild fruits into the extraordinary range of forms we see today, from tiny chiltepins to enormous bell peppers.
There was, however, no single pepper domestication event. At least five species of Capsicum were independently domesticated in the Americas.
That distinction is important because what we casually call “different kinds of peppers” can mean two very different things. A jalapeño and a bell pepper are different varieties of the Capsicum annuum species, while habanero peppers belong to the Capsicum chinense species.
Capsicum chinense includes many of the world’s hottest peppers, which I’ll be getting to in a bit. The scientific name is misleading. Chinense means “Chinese,” but the species did not originate in China. The name resulted from an eighteenth-century taxonomic mistake, when European botanists encountered peppers that had already spread throughout Asia and assumed they might have originated there.
Perhaps the most striking thing about the history of peppers is how rapidly they conquered the world.
Before roughly 1500, no one in Europe, Africa, or Asia had ever encountered a Capsicum pepper.
Spanish and especially Portuguese trading networks carried Capsicum seeds across the Atlantic and Indian Oceans during the sixteenth century.
Peppers had several advantages as a global crop. They grew easily in tropical and subtropical climates, produced large quantities of fruit, could be grown locally rather than imported from Asia, as with black pepper, and dried extremely well.
Within remarkably little time, peppers had reached Africa, India, Southeast Asia, China, Korea, and Japan.
India adopted chili peppers particularly enthusiastically.
Prior to their arrival, Indians already had several ways of producing pungency in their dishes, including black pepper, long pepper, ginger, and mustard. Capsicum peppers provided an inexpensive, easily cultivated source of intense heat.
They eventually became so important to Indian cuisine that it is difficult to imagine many regional Indian dishes without them, despite their relatively recent arrival.
Although Europeans introduced them to the Old World, hot peppers never really caught on in European cuisine the way they did in Asia and Africa.
One question that many people have asked is why hot and spicy cuisines are more prominent in warm latitudes. There is a real correlation between hot climates and the use of strongly spiced foods, but there probably is not a single explanation.
The strongest hypothesis concerns food preservation and microbes.
Before refrigeration, food spoiled much more rapidly in warm climates because bacteria and fungi reproduce faster at higher temperatures. Many traditional spices contain compounds that inhibit microorganisms.
Researchers Paul Sherman and Jennifer Billing compared traditional recipes from dozens of countries and found that cuisines from hotter climates tended to use more spices, particularly spices with strong antimicrobial properties. They argued that the use of spices may have provided an advantage by reducing foodborne illness.
Chili peppers fit into this pattern. Capsaicin has antimicrobial properties, although chili is only one of many antimicrobial ingredients. Garlic, onion, oregano, cloves, and other spices can also inhibit various microorganisms.
Traditional cuisines often combine several of them. The correlation between temperature and spice use was particularly noticeable in meat dishes, which would have presented a serious spoilage problem in tropical climates before refrigeration.
There is also the fact that chili peppers grow better in tropical climates.
Chili peppers are hot, but that isn’t binary. Some are hotter than others, and some are really, really hot.
The sense of taste isn’t something that is easily quantifiable. We can quantify light and sound, but taste doesn’t lend itself to numbers. In 1912, a pharmacist named Wilbur Scoville attempted to solve this problem, at least for measuring heat.
He developed the Scoville Organoleptic Test. Organoleptic is a fancy word that refers to the qualities of a food substance that stimulate sense organs.
A measured pepper extract was repeatedly diluted, traditionally with a sweetened solution, and presented to human tasters. Dilution continued until the tasters could no longer detect the burning sensation.
The amount of dilution necessary became the pepper’s Scoville rating. If an extract had to be diluted approximately 5,000-fold before its heat could no longer be detected, it would be assigned roughly 5,000 Scoville Heat Units, or SHU.
The system worked remarkably well for its time, but it had an obvious weakness: human beings were the measuring instruments.
People have different sensitivities to capsaicin. Repeated tasting also causes sensory fatigue. Someone who has just tasted an extremely hot sample may judge the next one differently from someone starting fresh.
Modern laboratories usually do not assemble panels of people and make them repeatedly drink pepper extract. Instead, pepper heat is generally measured chemically using high-performance liquid chromatography, or HPLC.
A pepper sample is dried and ground, its capsaicinoids are extracted, and the chromatography equipment separates and measures the different heat-producing molecules.
The resulting concentration can then be mathematically converted into the familiar Scoville Heat Unit scale. A commonly used rough conversion is that 1 part per million of capsaicinoids corresponds to approximately 16 SHU on a dry-weight basis.
Over time, as with all cultivated plants, peppers have been bred for certain properties, particularly capsaicin. The range of heat levels can vary greatly.
At the bottom of the scale are bell peppers, which typically have a SHU value of 0.
Mild Anaheim and New Mexico peppers may range from roughly 500 to several thousand SHU. Jalapeños typically range from 2,500 to 8,000 SHU. Serranos are usually somewhere around 10,000 to 25,000 SHU.
Cayenne peppers commonly reach approximately 30,000 to 50,000 SHU. Many Thai chiles and bird’s-eye peppers occupy roughly the 50,000 to 100,000 SHU range.
Habaneros and Scotch bonnets commonly reach roughly 100,000 to 350,000 SHU, although hotter versions can exceed that considerably.
Several decades ago, a quest began to find and create hotter and hotter peppers. There is a niche market for hot sauces featuring many ultra-hot peppers, as some people want hotter and hotter experiences.
In 2007, Guinness World Records listed the Ghost pepper as the world’s hottest pepper. It has an SHU between 855,000 and 1,040,000. The Ghost pepper is native to northern India and is believed to have been a natural hybrid.
However, since then, a series of record-setting peppers has been the result of intentional selective breeding.
In 2011, three different peppers set records for being the hottest. In February, the Infinity Chili set a record at 1,067,286 SHU; a few days later, the Naga Viper was recorded at 1,382,118 SHU, and in June, the “Butch T” strain of the Trinidad Scorpion pepper came in at 1,463,700 SHU.
In 2013, the title was taken by Ed Currie of South Carolina, who developed a new pepper called the Carolina Reaper. The Carolina Reaper was originally measured at 1,569,300 SHU but has later been updated to 1.64 million SHU.
The current record holder is another pepper developed by Ed Currie, known as Pepper X. In 2023, it had a measured value of 2,693,000 SHU.
The increase in pepper hotness over the sixteen-year period from 2007 to 2023 was astonishing. In 2007, the record was just over 1 million SHU. By 2023, it was nearly 2.7 million SHU, indicating that selective breeding increased the recognized record by roughly 169 percent.
This trend is not over. Ed Currie has announced he created a pepper hotter than Pepper X. In a 2025 interview, he said the new variety was essentially ready, but that he wanted extensive testing and expected to wait a few years before releasing it.
How hot could a pepper theoretically get? Pure capsaicin corresponds to roughly 16 million SHU. A pepper will probably never achieve that, but there is still a lot of room for still hotter peppers than the current record.
Whatever Ed Currie’s never pepper is might break the 3 million SHU barrier.
The global market for Capsicum peppers is enormous, although estimates vary depending on whether the calculation includes only fresh peppers or also dried chilies, powders, sauces, extracts, and processed products.
For the broadest definition of the Capsicum market, one 2026 industry estimate values it at roughly $77 billion worldwide, up from about $73 billion in 2025. It projects the market could exceed $120 billion by 2034. Asia-Pacific accounts for more than half of global revenue, reflecting both enormous production and consumption in countries such as China and India.
Peppers are not staple foods like wheat, potatoes, or rice, but they have had a profound impact. Even though they were native to the Americas, they have come to define entire cuisines across multiple regions worldwide.