Outline_7._How_to_Make_an_Almond

1、HOW TO MAKE AN ALMONDHow were plants domesticated? How do certain wild plants get turned into crops? How was plant domestication accomplished? Domestication defined as growing a plant and making it change genetically from its wild ancestor making it more useful for human consumption Peas domesticate

2、d in 8000 BC; strawberries in Middle ages; The Process of Domestication Plants dont walk or fly so how can they disperse their seeds? - wind, water float, or hitchhiking on other species An evolutionary process strawberries that happened to turn red and sweet became favorite of animals and thus thei

3、r seeds were dispersed Animals do modify the genes of plants but dont consciously plant themTurtle Eating StrawberryHumans are selective in picking seeds Humans disperse only particular seeds of a plant. Criteria for selection:Size larger fruits make picking more worthwhile; Peas now 10 times heavie

4、r than earlier forebearers Criteria for selection: Sweetness vs. bitterness plants evolved to have bitter or poisonous early fruit so they would not be eaten but seeds need to stay bitter to avoid being eaten and spat out A few seeds, by chance, would not have been bitter and it is these that farmer

5、s would choose to plant or first choose to eat. Almonds domesticated by 3000bc. Lima beans, watermelons, potatoes, eggplants, cabbages all once had bitter or poisonous ancestors Seedlessness more flesh and fewer seeds the more useful for consumption bananas now seedless along with some watermelons a

6、nd so on. Humans are selective in picking seeds Humans disperse only particular seeds of a plant. Criteria for selection:Oily seeds oil in flax亚麻, cotton, sesame, mustard芥菜, poppies found to have consumable usesHumans are selective in picking seeds Humans disperse only particular seeds of a plant. C

7、riteria for selection:Length of fibers plants like cotton began to be used for weaving for textiles. Stems of flax (linen亚麻 one of oldest textiles chief one in Europe before industrial revolution) and hemp大麻纤维 selected for straightness.Gatherers of wild plants unknowingly change the nature of the pl

8、ants Pods of peas have mechanism to disperse seeds. Some plants have germination萌芽inhibitors to guard against drought or other severe conditions, but only the ones immediately germinating will be gatheredPea podGatherers of wild plants unknowingly change the nature of the plants Farming changed the

9、conditions for selection of wild plants some were favored and conditions of sowing, tilling, watering favored some features over others. Big seeds did better in dense conditions, for example, while small seeds did better in drier dispersed conditions.Why are some plants easier to domesticate than ot

10、hers? Wheat, barley大麦, and peas domesticated around 10,000 yrs ago Edible and gave high yields in wildEasily grown by sowing or plantingGrew quicklyReadily storedMostly self-pollinating自花传粉 Wild genetic ancestors required little genetic change to be converted into crops Fruit and nut trees hard to c

11、ultivate Some Fruit and nut trees domesticated around 4000 BC olives, figs, dates, pomegranates, and grapes Didnt yield fruit until 3 years after planting and full production not until 10 yrs after planting those committing to planting them must already have been settled in village life Growable fro

12、m seeds or cuttings (permitted exact cloning)Other fruit trees even harder to cultivate apples, pears, plums, cherries Not growable from cuttings or seeds Only cultivable thru difficult process of grafting嫁接法 Require cross-pollination异花授粉from different variety of speciesOther crops Weeds in fields o

13、f cultivated crops (rye, oats, turnips甘蓝, radishes萝卜, beets甜菜, leeks韭菜, lettuce 莴苣, 生菜) arose with less effortCereals and pulses Cereal and pulse combination is good one for feeding people and launched food production in many areas Cereals are high in carbohydrates, are fast growing and yield up to

14、a ton per acre Cereals account for half of calories consumed today and 5 (wheat, corn, rice, barley, and sorghum高粱) of leading 12 crops produced in world Cereals low in protein but pulses are high (25% in some cases)Cereals and pulses Wheat, barley, peas in Fertile Crescent; corn, several bean speci

15、es in MesoAmerica; rice and millets with soybeans and other beans in China; sorghum, African rice, pearl millet珍珠 粟 ， 御 谷 w i t h cow p e a s 豇 豆 a n d groundnuts落花生in Africa; Early centers of food production also had crops that yielded fibers (flax in Fertile Crescent) only Eastern US and New Guine

16、a lacked fiber cropDifferences in early food production Old World involved broadcast seeding (seeds thrown in handfuls resulting in monocultural fields), monocultural单一作物 fields, plowing with large mammals New World no large mammals domesticated for plowing. Planting by hand-held sticks or hoes锄头. S

17、eeds individually planted. Mixed gardens not monoculture Source of carbohydrates not cereals, but tubers and roots, in some areas, e.g., potatoes and yams山药, especially in tropical areasCrops cultivated at different times By Roman times, nearly all leading crops were cultivated(strawberries and raspberries树莓 in Medi