The origins of agriculture in the Americas

Abstract

AbstractThree independent centers of domestication and agricultural origin have been identified in the Americas: the south‐central Andes, Mexico, and most recently, eastern North America. Much of the evidence for early domesticates in these three regions has been excavated from higher elevation dry caves and rock shelters. These sites contain remarkably well preserved plant and animal remains, along with a record of short‐term occupation by small groups of hunter‐gatherers and early cultivators. As a result it has long been thought that plants and animals were brought under domestication in the Americas by small, seasonally mobile societies living in upland settings. The age of small seeds and other plant materials recovered from such dry caves and believed to represent early domesticates was, of necessity, determined indirectly, through conventional large‐sample radiocarbon dating of organic material thought to be contemporaneous. In each of the three regions, the earliest domesticates were believed to date between 7,000 and 10,000 B.P. The origin of agriculture in the Americas was thought to be roughly contemporary with the transition from foraging to farming in the Near East (Fertile Crescent, ca. 10,000 B.P.) and China (Yangtze Corridor, ca. 8,500 B.P.). Since the mid‐1980s, however, the age of many of the proposed early domesticates in the Americas, as well as their contexts of domestication, have been re‐examined, beginning in eastern North America.The excavation of larger and more sedentary river valley settlements in eastern North America has yielded ample evidence of the cultivation of domesticated seed plants. This evidence is as old as or older than that recovered from seasonally occupied upland caves and rock shelters. In addition, a new and more rigorous standard for evidence of domestication has been adopted in eastern North America. That standard, which requires direct dating of seeds and other plant parts that exhibit clear, unequivocal, and well‐documented morphological markers of domestication, is now being applied throughout the Americas, producing conservative timetables of domestication and agricultural origins that contradict alternative, more speculative chronological frameworks.Under the new standard of evidence, domestication of plants in all three independent centers (and in the Andes, domestication of animals) appears to have taken place between about 5,500 and 4,000 years ago, much more recently than previously was thought. Several lines of evidence also suggest that the Native American societies that first brought these species under domestication may not have been exclusively seasonally mobile hunter‐gatherers of higher‐elevation environments. In each of the three regions, domesticates recovered from upland caves may reflect a transition to a farming way of life accomplished by societies occupying more sedentary settlements in river valleys. In some cases, upland caves containing domesticates may represent one component in the seasonal round of early food production by societies occupying nearby river valleys; in others, they may mark the subsequent expansion of food production economies out of rich river valley resource zones into adjacent upland environments.