Maize was domesticated in central Mexico and spread from the southwest through North America, along with symbiotic “Three Sisters” agriculture, in which corn, beans, and squash growing in the same mound enhanced the productivity of each plant. Native American skill in agriculture provided the margin of survival for the early European colonists, either through trade or direct sharing of expertise, and agricultural products native to the Americas quickly became staples throughout Europe. Three Sisters symbiotic agriculture—planting corn, climbing beans, and squash together in the same plot—also originated in central Mexico and probably spread simultaneously with the corn. In this efficient planting method, corn stalks provided support for the bean vines, which added nitrogen to the soil. Squash provided ground cover, which discouraged weeds. Productivity was much higher (by some estimates as much as 30 percent) for the three grown together than each grown separately.
