Of the 10 historically recognized independent centers of plant domestication worldwide, five were in the Americas.

Three of these occurred in South America, where chile peppers, squash, beans, yucca, yams and white and sweet potatoes were grown. North America’s contributions included squash, maize (corn) and beans – the trifecta of New World foods – as well as other species such as chile peppers and sunflowers, the seeds of which were consumed.

Until the last few decades, some researchers thought that North American agriculture developed in Mexico approximately 5,000 years ago, whereas wheat and barley were domesticated in the Near East around 10,000 years ago. Recent discoveries, however, have dramatically changed the North American dates while identifying new regions where early domestication took place.

The transition from nomadic hunting-and-foraging cultures to settled societies occurred in different places around the world at different times, but researchers now agree that New World agriculture started 10,000 years ago. Dolores Piperno of the Smithsonian Institution says that agriculture began in southwest Mexico.

Around 8,000 B.C., the cold, arid climate became warmer and wetter as atmospheric carbon dioxide levels rose. In Mesoamerica, lowlands and tropical forests expanded, lakes filled with water, and new plant and animal species replaced old ones. People planted on these lake shores.

In 1997, Smithsonian archaeologist Bruce Smith dated the seeds of a domesticated pepo (pumpkin) squash found in a cave in Oaxaca, Mexico, to nearly 10,000 B.C., which to date is North America’s oldest known domesticated plant.

Phytoliths – fossilized mineral particles left by plants – from squash and arrow root indicate that these plants were being grown in Panama 9,000 years ago.

Maize was one of the New World’s earliest crops, as well as one of its most important. A domesticated form of the wild grass teosinte maize is rich in carbohydrates. It’s easy to store and can be ground into flour to make different foods.

Maize remained in dry caves in the semi-arid highland dating to 5,000 years ago. They assumed that was the beginning of maize or corn domestication. In fact, farmers were planting maize earlier elsewhere. Mary Pohl and Kevin Pope discovered evidence that farmers cleared forests, most likely for fields, 7,000 years ago.