From The National Geographic:
Domesticated chili peppers started to spice up dishes across the Americas at least 6,000 years ago, according to new research tracing the early spread of the crop. Peppers quickly spread around the world after Christopher Columbus brought them back to Europe at the end of the 15th century, but their ancient history had been poorly known until now. “We’re excited to be able to finally trace this spice,” said Linda Perry, an anthropologist at the Smithsonian Institution’s National Museum of Natural History. The researchers were intrigued by starch grains they found on artifacts collected at seven sites ranging from the Bahamas to southern Peru. The grains look like tiny jelly doughnuts squished in their middles and didn’t match those from obvious starchy foods such as potatoes, cassava, and other roots.
“It was only by accident that I figured out their source,” Perry said. The earliest chili pepper starch grains were found at two sites in southwestern Ecuador that are dated to about 6,100 years ago.