托福阅读的文章中经常会讨论到农业社会出现的原因，常见的原因有：

　　1.Population crisis

　　因为人口的增加，导致食物的短缺，所以，农业的出现可以保证更加稳定和充足的食物来源。

　　2.Climatic change

　　在大约一万三千前，冰河世纪结束，气温的上升，导致食物资源的增加，导致人口的迅速上升，之后，气候又出现了比较大波动，尤其是降水量的波动，导致干旱时期的食物资源短缺，于是农业成了解决这一问题的答案。

　　3.Mental elements

　　还有一些考古学家，把农业的出现归因于人类的认知和思想的发展。比如人类发明了可以收获和加工农产品的工具;把动物或者植物作为社会地位和权力的象征;和动物之间建立亲密的“社会关系”等。

　　这几大因素，可能共同导致了农业的出现。

　　了解了这些信息之后，

　　再去做农业相关话题文章就会很轻松。

　　比如下面这个题目：

　　How did it come about that farming developed independently in a number of world centers (the Southeast Asian mainland, Southwest Asia, Central America, lowland and highland South America, and equatorial Africa) at more or less the same time? Agriculture developed slowly among populations that had an extensive knowledge of plants and animals. Changing from hunting and gathering to agriculture had no immediate advantages. To start with, it forced the population to abandon the nomad's life and became sedentary, to develop methods of storage and, often, systems of irrigation. While hunter-gatherers always had the option of moving elsewhere when the resources were exhausted, this became more difficult with farming. Furthermore, as the archaeological record shows, the state of health of agriculturalists was worse than that of their contemporary hunter-gatherers.

　　According to paragraph 1, all of the following are advantages of hunting and gathering over agriculture EXCEPT:

　　A.It is a healthier lifestyle.

　　B.It requires less knowledge of plants and animals.

　　C.It does not need storage capabilities.

　　D.t is not tied to any specific location.

　　这个题干问到的是hunting-gathering society的优势，通过前面表格的对比，以及文章中的内容，可以看出hunting-gathering society也是需要充分了解动植物的习性，才能更好的完成狩猎和采集，所以答案为B选项。