Which effects were seen in North America after 1900 as a result of agricultural changes in developed countries?​

This is going to be a lot but I’m trying to help. :) There are a variety of hypotheses as to why humans stopped foraging and started farming. Population pressure may have caused increased competition for food and the need to cultivate new foods; people may have shifted to farming in order to involve elders and children in food production; humans may have learned to depend on plants they modified in early domestication attempts and in turn, those plants may have become dependent on humans. With new technology come new and ever-evolving theories about how and why the agricultural revolution began. Regardless of how and why humans began to move away from hunting and foraging, they continued to become more settled. This was in part due to their increasing domestication of plants. Humans are thought to have gathered plants and their seeds as early as 23,000 years ago, and to have started farming cereal grains like barley as early as 11,000 years ago. Afterward, they moved on to protein-rich foods like peas and lentils. As these early farmers became better at cultivating food, they may have produced surplus seeds and crops that required storage. This would have both spurred population growth because of more consistent food availability and required a more settled way of life with the need to store seeds and tend crop