The Development of Social Complexity

For most of human history, we have foraged (hunted, fished, and collected wild plants) for food. Small nomadic（流浪迁徙） groups could easily supply the necessities for their families.No one needed more, and providing for more than one’s needs made little sense. The organization of such societies could be rather simple, revolving around age and gender categories. Such societies likely were largely egalitarian（平等主义的）, beyond distinctions based on age and gender, virtually all people had equivalent rights, status, and access to resources.///原始部落

Archaeologist Donald Henry suggests that the combination of a rich habitat and sedentism (permanent, year-round settlement) led to a dramatic increase in human population. In his view, nomadic, simple foragers have relatively low levels of fertility（生育能力）. Their high-protein, low-carbohydrate diets result in low body-fat levels, which are commonly associated with low fertility in women. High levels of physical activity and long periods of nursing, which are common among modern simple foragers, probably also contributed to low levels of female fertility if they were likewise common among ancient foragers.///人口低增长率原因

In Henry's view, the adoption of a more settled existence in areas with abundant food resources would have contributed to higher fertility levels among the sedentary（久坐的) foragers. ///A diet higher in wild cereals（谷物） produces proportionally more body fat, leading to higher fertility among women. Cereals, which are easy to digest, would have supplemented（补充） and then replaced mother's milk as the primary food for older infants. ///Since women are less fertile when they are breast-feeding, substituting cereals for mother's milk would have resulted in closer spacing of births and the potential for a greater number of live births for each woman. ///A more sedentary existence may also have lowered infant mortality and perhaps increased longevity among the aged. These more vulnerable members of society could safely stay in a fixed village rather than be forced regularly to move great distances as part of a nomadic existence, with its greater risk of accidents and trauma.（创伤）///更高的生育率

All of these factors may have resulted in a trend of increasing size among some local human populations in the Holocene (since 9600 B C E ). Given sufficient time, even in very rich habitats, human population size can reach carrying capacity, the maximum population an area can sustain within the context of a given subsistence system. ///And human population growth is like a runaway tram（脱轨电车） once it picks up speed, it is difficult to control. So even after reaching an area’s carrying capacity, Holocene human populations probably continued to grow in food-rich regions, overshooting（超越） the ability of the territory to feed the population, again within the context of the same subsistence strategy. In some areas, small changes in climate or minor changes in plant characteristics may have further destabilized local economies.///超过人口量

One possible response to surpassing the carrying capacity of a region is for a group to exploit adjoining land. However, good land may itself be limited—for example,within the confines of a river valley where neighbors are in the same position, having filled up the whole of the desirable habitat available in their home territories, expansion is also problematic. Impinging（冒犯） on the neighbors' territory can lead to conflict, especially when they too are up against the capacity of the land to provide enough food.///资源分配不均，冲突

Another option is to stay in the same area but to shift and intensify the food quest（追求） there. The impulse to produce more food to feed a growing population was satisfied in some areas by the development of more-complex subsistence strategies involving intensive labor and requiring more cooperation and greater coordination among the increasing numbers of people. This development resulted in a change in the social and economic equations that defined those societies. Hierarchies（层级） that did not exist in earlier foraging groups but that were helpful in structuring cooperative labor and in organizing more-complex technologies probably became established, even before domestication and agriculture, as pre-Neolithic societies (before the tenth millennium B C E) reacted to the population increase.///阶级产生

1.原始部落

2.低生育率

3.环境改变，农业社会，生育率上升

4.产生矛盾

5、6解决办法