section_path: Plants
section_name: Plants
paragraph_text: Plants
  
  Humans foraged for wild cereals, seeds, and nuts thousands of years before they were domesticated; wild wheat and barley, for example, were gathered in the Levant at least 23,000 years ago. Neolithic societies in West Asia first began to cultivate and then domesticate some of these plants around 13,000 to 11,000 years ago. The founder crops of the West Asian Neolithic included cereals (emmer, einkorn wheat, barley), pulses (lentil, pea, chickpea, bitter vetch), and flax. Other plants were independently domesticated in 13 centers of origin (subdivided into 24 areas) of the Americas, Africa, and Asia (the Middle East, South Asia, the Far East, and New Guinea and Wallacea); in some thirteen of these regions people began to cultivate grasses and grains. Rice was first cultivated in East Asia. Sorghum was widely cultivated in sub-Saharan Africa, while peanuts, squash, cotton, maize, potatoes, and cassava were domesticated in the Americas.
  
  Continued domestication was gradual and geographically diffuse – happening in many small steps and spread over a wide area – on the evidence of both archaeology and genetics. It was a process of intermittent trial and error and often resulted in diverging traits and characteristics.
  
  Whereas domestication of animals impacted most on the genes that controlled behavior, that of plants impacted most on the genes that controlled morphology (seed size, plant architecture, dispersal mechanisms) and physiology (timing of germination or ripening), as in the domestication of wheat. Wild wheat shatters and falls to the ground to reseed itself when ripe, but domesticated wheat stays on the stem for easier harvesting. This change was possible because of a random mutation in the wild populations at the beginning of wheat's cultivation. Wheat with this mutation was harvested more frequently and became the seed for the next crop. Therefore, without realizing it, early farmers selected for this mutation. The result is domesticated wheat, which relies on farmers for its reproduction and dissemination.