The eye-watering moment when chili peppers first spiced up the palates of early Americans has long been a subject of speculation for New World archaeologists and culinary historians alike. For years, archaeologists have assumed that the organic remains of the first chilies—plants of the genus Capsicum—eaten by humans did not survive the ravages of time well enough for their appearance to ever be chronicled in the archaeological record.

Now, a scientist at the Smithsonian has discovered evidence in the form of microscopic starch grains that, when linked with archaeological stone tools, reveal precisely when and where early Americans began enjoying chilies in their meals.
The discovery by archaeobiology postdoctoral fellow Linda Perry of the Smithsonian's National Museum of Natural History and her colleagues was recently published in the journal Science. Their work is yielding new information about a food that is popular worldwide and gives insight into early human settlements in Central and South America.

"It is hard to imagine modern Latin American cuisine without chili peppers," says Delores Piperno, an archaeobotanist at the Natural History Museum and the Smithsonian Tropical Research Institute in Panama and one of the co-authors of the article. Scientists now know that "prehistoric people, from the Bahamas to Peru, were using chilies in a variety of foods a long time ago. Peppers would have enhanced the flavor of early cultivars, such as maize and manioc, and may have contributed to the rapid spread of these cultivars after they were domesticated."

Indigestion

The discovery of ancient chili pepper starch grains was a "eureka!" moment of sorts, Perry explains, "something that came up quite by accident." It occurred after Perry deduced that the unidentified microscopic remains of plants that she and her colleagues had been finding at various ancient settlement sites in the Americas might, in fact, be chili pepper starch grains.

"There are just a few researchers in the Americas who work with starch microfossils," Perry says. "We know one another well and communicate and share images. People were sending me images of microscopic starch grains they'd found at archaeological sites. They were grains that we couldn’t identify yet were simply everywhere. Nobody knew what they were."

The researchers had previously identified starch from a number of domesticated plants, such as corn, beans and squash, at archaeological sites. Noting that chili peppers sometimes cause indigestion and that undigested starch is often the source of this condition, Perry’s suspicions were aroused.

"I thought, 'My goodness, what if peppers have starch?'" she recalls. "So I came back to the lab, got a little sample of a pepper out of my reference collection, smeared it on a microscope slide, and there was our unknown." As it turns out, the starch grains are the only part of the pepper plant that can survive the passage of millennia in a tropical climate.

Distinctive shapes

Starch grains are the equivalent of fat cells for plants, Perry explains. Through photosynthesis, plants process carbon dioxide with the energy from sunlight to produce glucose. This winds up as food that can be stored for later use in the form of starch—packaged in starch grains. The grains themselves are semi-crystalline structures that under a microscope resemble smooth river stones. Through processes not yet understood by scientists, starch grains can persist for eons.

While searching for blood residue on 28,000-year-old stone tools in the Solomon Islands in 1994, Australian archaeologist Tom Loy first identified the microscopic remains of plant starch grains crushed into the crevices of the implements. Loy was the first to realize the identity of the plants could be determined by the distinctive shapes of their starch grains. Loy's work opened a new window onto the past. Now, instead of theorizing about the development of agriculture, researchers could analyze physical evidence of the plants themselves.

Complex cuisine

To date, the oldest chili starch grains have been found in southwestern Ecuador at two human settlement sites dating to 6,100 years ago. The chili remains were associated with previously identified starch grains of corn, arrowroot, yuca, squash, beans, palm fruit and other plants, adding to the picture of an early, complex agricultural system in this region.

But Ecuador is not considered to be a center of domestication for any of the five domesticated chili species. A more ancient record of the domestication and spread of chili peppers awaits investigators working in other regions where wild chilies were first brought into cultivation.

In Panama, chili peppers have been found with evidence of corn and domesticated yams dating back some 5,600 years. Chilies also were found at a site occupied 4,000 years ago in the Peruvian Andes, along with microscopic remains of corn, arrowroot and possibly potato. In this case, the chilies were identified as the species C. pubescens. The rocoto pepper, a cultivar of this species, is still a staple in the Peruvian diet. More recently settled sites in the Bahamas and Venezuela also have yielded remains of both corn and chilies.

Perry's discovery has given archaeobiologists an important tool for understanding how New World agriculture developed. The antiquity of chili peppers sheds a revealing new light on the day-to-day existence of early Americans. "If people were deliberately cultivating chilies, a nonstaple crop, this is an indication that they weren't living on the margins. They had to have enough to eat in order to be able to experiment with other foods just to add to their enjoyment," Perry says. Her pepper discovery is revealing evidence of "a complex cuisine at a very early time"