Origins of Agriculture 1/7 (read 180-181, a closer look 11.1 & centers of plant domestication)
* humans have existed as species ~ 195,000 years/ farming has been practiced ~ 11,500 years. * Knowledge of foraging societies:
* archaeological evidence: middens (trash pile – bones, corn cobs, etc.) & coprolites (fossilized fecal material, to get an idea of what people ate) * modern evidence: !Kung, Ainu
* Why did we start farming?
* easier, it is possible to have a stable home
* theory of the brilliant sage: sow seeds > grow crops, which could be discovered by plants growing in middens from discarded seeds or, the seeds buried with dead sprouted * agriculture spread rapidly from single source
* Did agriculture start in 1 region?
* fertile crescent, cradle of agriculture
* but signs point to agriculture starting in China, Papua, New Guinea, and Americas around the same time * Possible reasons for the start of agriculture:
* climate change in middle east: people clustered around remaining larger water supplies – population increase forced people to start farming * population increase: may have gotten to big to support hunter-gatherer lifestyle * Agriculture
* Agriculture = cultivation of plants
* domestication = genetic alteration of plants by humans * selection: occurs constantly in populations of plants – certain characteristics are being selected for or against * Natural Selection: occurs in wild populations containing natural variation – environment selects for survival value * Artificial Selection: occurs in domesticated populations containing natural variation – humans select for certain traints. * not necessarily beneficial to plant. ex: nonshattering grains (when mature grains will easily fall off plants, we selected for plants with grains that stay on the plants) & lack of dormancy (plants usually wait to sprout in spring, we select for plants with no dormancy period). * Selection
* selected traits can be passed to offspring through reproduction * plants reproduce both sexually and asexually
A Closer Look – Forensic Botany
* archeologists make extensive use of plant remains in reconstructing ancient lifestyle of foraging & agriculture. * not all plants are well preserved: seeds, wood, pollen, phytoliths, starch grains, & fibers are among most informative recoverable remains – lignified walls of wood & fibers are more resistant to decay b/c can only be degraded by few types of fungi. * Phytoliths (“plant stones”) crystals formed & found in plants – created within epidermal cells or b/t plant cells. – after a plant decays, phytoliths are released into the soil & can remain intact for thousands of years. * very distinctive in shape & size can be used to identify presence of a particular plant family, genus, or species. – can separate wild species from domesticated ones & proven especially useful in dating the origin of agriculture. * can also be applied to forensic science – identification of plants used as incriminating evidence.
Centers of Plant Domestication
* When agriculture evolved, native peoples developed indigenous crops, but ones suitable for agriculture slowly spread to surrounding regions as people traded & migrated. * >emergence of principle crops associated w/major centers of the world * Near East: wheat & barley were dietary staples; Far East: rice; Africa: sorghum and millet; Mesoamerica, corn; South America, potato & root crops. * As civilization developed, crops became more successful outside of their native lands: potatoes associated with Irish, native to Peru, etc. * Pinpointing origin of important crops – Nikolai I. Vavilov * directed plant-collecting expeditions around the world & examined thousands of...