Crop origins and evolution

The origins of agriculture and domesticated crops are intertwined, and the change from a hunter-gatherer mode to tillage, sowing and harvesting was one of the major technologcal innovations of humankind. This occured some 10,000 years ago in several different locations, and involved the domestication of wild-relatives of the major crops (see History of Agriculture).

Domestication involves changes in the genetic makeup and morphological appearance of plants (and animals) but the wild-relatives of crop continue today to be important sources of genetic diversity and of traits for protection of domesticated crops from stress and disease (see Plant breeding) and to ensure food security. Knowledge of crop origins is thus of considerable practical importance.

Development today of new crops (such as perennial alternatives of currently used annual staples) has potential value is helping meet serious current agricultural challenges such as the need for water use efficiency, better management of land salinization, and soil conservation.

Tracing the ancestors of crops

Age of earliest crop remains
Location	Crop	Age
		(years before present)
Mesoamerica	Squash	10,000
Mesoamerica	Maize	6,300
Central America	Cassava, Dioscorea yam,	7,000 to 5,000
	arrowroot, maize
Fertile Crescent	Einkorn wheat	9,400 to 9,000
Fertile Crescent	Lentil	9,500 to 9,000
Fertile Crescent	Flax	9,200 to 8,500
China	Rice	9,000 to 8,000

(After Paul Gepts, 2003, in Chapter 13 of Plants, Genes and Crop Biotechnology, Chrispeels and Sadava.)

The earliest origins of major crops based on carbon-14 dating, date back around 10,000 years, just after the end of the last ice age. This allows the geographicals in which crops domestication took place to be identified.

Six independent centers of origin can be nominated:

• Mesoamerica (Southern Mexico and Northern Central America): Maize, Phaseolus beans, Sweet potato, tomato
• The Andes of South America: Potato, cassava (manioc), pineapple
• Southwest Asia (including the "Fertile Crescent": Wheat, barley, pea, lentil
• The Sahel region and Ethiopian highlands of Africa: Sorghum, cofee, melon, watermelon
• China: Asian rice, soybean, adzuki bean, orange, apricot, peach, tea
• Southeast Asia:Cucumber, banana, plantain

)

Wheat domestication in the Middle East

See also Wheat

Rice domestication in Asia and Western Africa

See also Rice

Maize and bean domestication in the Americas

See also Maize

New crops by hybridization and polyploidy

See also Plant breeding

Further reading

• Damania, A.,J., Valkoun, G. Willcox, and C. Qualset, eds. (1998). The Origins of Agriculture and Crop Domestication, 1st ed.. International Center for Agricultural Research in the Dry Areas, Aleppo, Syria. 
• de Candolle, A. (1992). Origin of Cultivated Plants, 1sh ed.. Cambridge, U.K.. 
• Diamond, Jared (1997). Guns, Germs and Steel: A Short History of Everybody for the Last 13,000 Years, 1st ed.. Vintage. ISBN 0-09-939278-0. 

• Frankel, O. H., A. H. D. Brown, and J.J. Burdon. (1995). The Conservation of Plant Biodiversity, 1st ed.. Cambridge University Press, Cambridge, U.K.. 
• Gepts, Paul. Chapter 13. Ten thousand years of crop evolution. In Chrispeels, Maarten J.; Sadava, David E. (editors) (2003). Plants, Genes and Crop Biotechnology, 2th ed.. Jones and Bartlett. ISBN 0-7637-1586-7. 
• Harlan J. R. (1992). Crops and Man, 2nd ed.. American Society of Agronomy, Madison, WI. 
• Vavilov, N. I. (1997). Five Continents.. Rome: International Plant Genetic Resources Institute; St. Petersburg: N. I.Vavilov All-Russian Institute of Plant Industry.. 

[[Category:Agriculture]