Hunters roam the landscape, subsisting on large mammals and gathering plants and other natural resources. Incipient agriculture begins in about 5000 B.C., and over the next thousand years includes low-intensity crops such as chili peppers, avocados, and beans. Excavations in the Tehuacán valley in central Mexico have uncovered small cobs of Zea mays—maize, or corn—dated to around 3000 B.C. It probably has little nutritional value at this stage, but by 2000 B.C., corn is one of the staple crops of Mesoamerican society and remains so for thousands of years.