It is proposed, on the basis of evidence from geological history and paleoclimatology, that annual grasses and legumes did not appear as significant components of the vegetation of Asia until the Neothermal, some 11,000 years B.P. The new combination of environmental factors which then became operative induced a widespread physiological and genetic change from a perennial to an annual habit in ecoclimatic zones in which annual types of ancestral perennials had not earlier occurred in any number. The annual prototypes of the Asian cereals and grain legumes therefore became rather suddenly and abundantly available to primitive man in his still biological ecosystems. Once this botanical revolution had occurred throughout the isoxerothermic zones around the inner cores of Asia, progress towards what came to be called civilizations, based on increasingly economic agricultural ecosystems involving cultivation and domestication of crops, followed in a gradual step-by-step manner.
Key wordscrop domestication annuals and perennials Gramineae Leguminosae Neothermal climate Asian prehistory
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