Origins of Plant Agriculture and Major Crop Plants

Agriculture is one of the most momentous inventions of humanity. It generated a surplus of food as a consequence of which a sizable fraction of societies were able to engage in economic activities other than agriculture. Thus, agriculture is considered to have been a prerequisite for the development of many civilizations throughout the world. It originated independently and at similar times (around 10 000 years ago) in different areas on several continents, notably Mesoamerica and South America, the Near East, the Sahel and Ethiopia, China, and Southeast Asia. Selection resulting from the cultivation and harvesting of plants by humans induced genetic modifications in these plants resulting in their domestication. In contrast to their wild progenitors, crop plants are unable to disperse their seeds and lack seed dormancy. They also have smaller plants but larger harvested organs (fruits, seeds, leaves) and contain lower amounts of toxic compounds. Flowering time is also less susceptible to environmental influences, mainly day-length. Following their domestication crop plants were widely dispersed across the globe, chiefly after the conquest of the Americas by the Europeans from 1492 on (the “Columbian exchange”). As a consequence of this dispersal, the assemblage of crops in any agricultural region is actually an assemblage originating throughout the world. During their evolution under cultivation, plants have been subjected to three reductions in genetic diversity. Therefore, wild progenitors and primitive cultivars in the areas of origin are a source of additional genetic diversity to further improve elite cultivars of our major crop plants.