Wandering the Sonoran Desert in search of the chiltepin—the ancestor to domesticated chile peppers—with MacArthur genius Gary Paul Nabhan

by Ari LeVaux

Since he started hunting for chile peppers, more than 40 years ago, Gary Paul Nabhan has followed them into dozens of rugged, tough-to-reach places. He’s hiked deep into the volcanic belt of southern Mexico, into caves that contained the oldest evidence of human use of chile pepper. He’s been mule-kicked, wounded by thornscrub, and bucked around while floating the Rio Grande through Big Bend National Park. But mostly Nabhan has logged countless blistering miles in the Sonoran and Chihuahuan Deserts, dodging storms, rattlesnakes, and citizen militias.

The Sonoran Desert, Nabhan’s adopted backyard, is one of the harshest environments in North America. Daytime temperatures regularly exceed 100 degrees. Sometimes the weather shifts and the temperature plummets 50 degrees in a few hours. It gets little rain, and much of what it does get falls during just a few months each summer. Nabhan calls his corner of Sonora “a military zone,” one that’s occupied mostly by migrants, border patrol, and armed patriots.

Which makes it a hard place for Nabhan’s quarry: the wild chiltepin, the ancestor of today’s chile peppers. The pepper isn’t just flavorful: it might offer a clue as to how plants can survive in dry, hot climates—like those we may see more of in the future. Chiltepines need more moisture and shade than the average Sonoran real estate can provide, so they have found a way to adapt: they grow under what are called nurse plants—vegetation that gives chiltepines shelter from the sun, wind, floods, desert creatures, and other dangers. Mesquite, ironwood, and hackberry are the most common nurse plants for chiltepines. They create spaces where moisture can gather and a chiltepin seed can germinate. For the rest of their lives, the branches, roots, trunk, thorns, and fruit of the nurse plant will shield, protect, and fertilize the pepper.

Most chiltepin plants are found in Mexico and Central America, though some have been found as far south as Peru. On the northern boundary, wild chiltepines grow in Texas, near Big Bend, and the Arizona borderlands about an hour south of Nabhan’s house outside Tucson.

Nabhan grew up in Gary, Indiana, which is not the sort of place you’d expect a love of peppers to form. Nabhan ate his first jalapeño in 1970, when he was an 18-year-old working on a railroad crew composed mostly of Mexican immigrants. After work, the crew would go to the International Wetbacks of the Americas Club, a Mexican restaurant in Gary’s red light district, where Nabhan once competed against a rabbit in a chile-eating contest. (Nabhan won.)

Though Nabhan remained an enthusiast, it wasn’t until he moved to Arizona that his obsession fully took hold. He arrived in 1972, when he transferred from Cornell College, in Iowa, to Prescott College. He stuck around after graduating in 1974 and began noticing that wild ancestors of cultivated crops—like corn and beans and chile—continued to be used. “I was in the Santa Cruz Chili and Spice Company, near the U.S. and Mexico border, and noticed that they were selling wild chiltepines in little packages,” Nabhan says.

Thousands of years ago, indigenous groups were using the chiltepin in their food. Over time, they began planting the seeds closer to their homes and breeding them to add spice and flavor. But wild chiltepines continue to grow without human help. The wild pepper is intensely hot. The first bite feels like an ember dropping onto your tongue—but then the fire quickly subsides. “You are left with the lingering taste of minerals, the thirsty desert earth itself,” Nabhan writes in Chasing Chiles, his thirtieth book. So when Nabhan first encountered them that day in 1977, he wanted to know where the owner of the store got them. “Back in the canyon behind the gift shop,” she said.

He mentioned the canyon to botanist Jack Kaiser, who said, “Yeah, I know about that stash.” A few days later, Kaiser took him to the chiltepin patch. At the time, Nabhan was a grad student at Arizona State University working on a master’s degree he received in 1978, the same year he was crowned as the wild chile–eating champion of Tucson. He earned a doctorate from ASU in 1983, all the while leading enthusiasts through the borderlands to visit the chiltepines—which are notoriously hard to spot, especially when they’re hiding beneath a nurse plant. It’s only during a short window in late summer, when the bushes blaze with lipstick-red pods, their tips pointing upward to the sky, that chiltepines are easily found.

As Nabhan learned more about the plant, he began to believe it was possible to “make sense of the world through the lens of the chile pepper,” forging folklore, archaeology, geography, ecology, and food into his studies. His current focus is observing how chiltepines respond and adapt to climate change, which involves getting as detailed a map of chiltepin populations as possible.

In 1990, Nabhan won a MacArthur “genius” grant. Nine years later, he and botanist Jack Kaiser were able to convince the U.S. Forest Service to designate a 2,500-acre stretch of rugged Tumacacori Highlands, in the Sonoran Desert, as the Wild Chile Botanical Area. “It’s the first botanical reserve for a wild ancestor of a cultivated crop,” he says. (It also encompasses the very canyon where Nabhan first encountered chiltepines.) In 2014, he convened a group of scholars and field workers to identify where and when the chile was first domesticated: near Puebla, Mexico, some 6,000 years ago.

In recent years, people north of the border seem to be catching on, too. “Chiltepines are undergoing a renewed popularity among chefs and bartenders and food providers,” says Nabhan. They are indispensable ingredients in the desert terroir that Nabhan has long championed in his books, many of which, not surprisingly, have been about chiles. “A variety of shrubs used in mixed drinks have chiltepin in the syrup. I run into chiltepin margaritas every two or three months in Tucson, Santa Fe, or El Paso.” In Mexico, chiltepines are often paired with fish, where the quickly passing heat is reminiscent of wasabi, something that has caught on with chefs north of the border.

Like any wild-foraged plant, though, finding chiltepines can be tough, particularly when entire populations can be damaged during extreme weather events. “In 2001 and 2002, we had catastrophic freezes that killed a lot of their nurse plants,” says Nabhan. “Then wildfires came through and burned many of the areas they were in.” To top it all off, a drought from 2007 to 2013 devastated habitat on both sides of the border.

But the chiltepin is a resilient plant. “With the last two years of very good rains in the borderlands, we’ve seen the wild harvest return to nearly what it was 20 years ago,” Nabhan says. Not only that, but Nabhan also believes that the plant is better-traveled than botanists have given it credit for. In April, he will be taking an exploratory trip to Baja to put the local chiltepines on the map. There are no official records of the plant in the region yet, but Nabhan knows it is there.

“I’ve eaten them,” he says. “I’ve seen enough bowls of them on tables. And the old men know where they are. I just have to find an old man to show me.”