Around 10,000 years ago, human civilization learned to cultivate food crops to sustain tribes, villages and towns. Without the benefit of agriculture, humans would need to hunt and gather their food like every other animal on the earth, eating enough to sustain but not enough to thrive. Population growth, settlement and free time resulted from learning to cultivate food. Nothing happens without consequence, however; agriculture also leads to habitat loss and soil degradation.
Increased Food Availability
For millions of years, humans and their evolutionary ancestors roamed savannas and forests hunting game and gathering edible plants. During this period, the global population changed very little, limited by ecological carrying capacity. With the advent of agriculture, food availability grew exponentially. Starvation decreased significantly, and family sizes increased when early people had enough food to support more offspring. While crop failures were possible, the overall trend of cultivating food instead of searching for it allowed for rapid growth and expansion of humanity.
Growing crops requires constant attention. Tribes that once traveled with nomadic tendencies quickly changed, as people learned to build basic shelter and irrigation. Agriculture marked the beginning of permanently settled areas, where generations could establish government, store food and raise livestock. Trade between villages commenced, as did cultural milestones such as art, architecture and music. Much of what people associate with society began as an indirect result of the need to stay in one place to grow crops.
Since finding food no longer required the efforts of a whole tribe but instead became the task of a relatively small group of farmers, the concept of free time emerged. With it came cultural activities and also the specialization of trades, such as tool-making, cloth-making and building. People could specialize in a task and use that knowledge to trade for items or services. Social classes and the exchange of ideas emerged from this new society.
As populations grow, so does the need for food. The most agriculturally productive land involves grasslands or forests, which must be cleared of native vegetation to make room for cultivated plants. This destruction of habitat causes declines in wildlife numbers and diversity as species must compete for fewer, and often lower quality, resources. Natural cycles get disrupted when established plant communities are cleared. Carbon is no longer fixed from the atmosphere into biomass or soil; and water runoff increases, while infiltration and aquifer recharge decreases.
High-quality soil is essential for food production. Without it, crops fail and famine ensues. In many cases worldwide, poor soil management is eroding countries' ability to grow their own food. For example, soil planted for too many consecutive years with corn turns from black to brown as the nitrogen is stripped out by the plants. Poorly terraced hillsides and farms with no cover crop experience large amounts of topsoil erosion, which can never be replaced. Large farming implements such as tractors and combines compress the soil beneath them, severely restricting gas exchange, rainfall percolation and microbial activity. These activities have the capability to render land infertile for generations.