To begin his discussion about why agriculture took longer to arise in some places than in others, Diamond compares the five areas of the world that have particularly fertile climates: southwest Asia’s Fertile Crescent, southwestern Europe, California, southwestern Australia, and South Africa’s Cape. Agriculture arose independently in the Fertile Crescent in 8500 BCE and spread to southwestern Europe around 5500 BCE. In the other three places, agriculture was absent until after 1500 CE, when colonists from Europe began carrying their crops and food production techniques to other continents.

Diamond explains that food production techniques evolved slowly over time. The lives of early farmers were not much different from the lives of hunter-gatherers; indeed, the first farmers had to work so hard to produce food that they tended to live shorter, less healthy lives than did their hunter-gatherer neighbors. Hunting and gathering cultures often existed side by side and traded with agricultural societies without adopting farming techniques. Some groups lived and still live in ways that blur the distinction between the two lifestyles.

A culture’s shift from eating all wild foods to eating mostly domesticated foods typically took thousands of years. In the intervening period, people constantly had to make choices about how to divide their time between their various food-producing and food-finding activities. Their choices would have been affected by their need for certain types of foods at certain times, their preferences for some foods over others, the amount of effort it took to get each kind of food, the chances that their effort to get food would be successful, and their cultural beliefs.

The first farmers on any continent could not have consciously chosen to become farmers because they had no prior knowledge of a farming lifestyle. After food production evolved, however, their neighbors did have a chance to compare the lifestyles. These neighbors could choose to adopt food-production techniques wholly or partially or to ignore them completely. It is not surprising that those who lived in areas where hunting and gathering was more difficult adopted food production faster than did those who lived in areas where hunting and gathering was relatively easy. Some cultures adopted food production piece by piece, and some adopted it for a while and then abandoned it again to return to a hunter-gatherer lifestyle.

Although the switch between lifestyles was not quick or simple, food production clearly had a competitive advantage over hunting and gathering. Over the past 10,000 years, nearly the entire world has shifted to food production. Although archaeologists and anthropologists do not agree on the exact reasons for this shift, several factors probably played a role. First, wild game and plant species became less available because of depletion by hunter-gatherers and because of climate changes on Earth. Also, the growth of technology made farming more advantageous over time. Increasing human population densities may have resulted from farming techniques, but they also created a pressure to produce more food within a given area, thus boosting the reward for creating better farming techniques.

All these factors probably played a role in the transition to farming in the Fertile Crescent in 8500 BCE. At that time in that climate, wild mammals were not as abundant as they had been previously, but wild cereals were becoming more abundant. People developed better techniques for harvesting and processing those cereals, and virtually all of those tools were useful for them after the transition to farming. Also, human population densities reached a point at which they needed the land to produce more food per acre than it was producing on its own. Ten or twenty thousand years before, the same possibilities and pressures were not present, so farming techniques did not arise.

Another reason populations tended to shift from hunting and gathering to food production was that food producers became more numerous. Larger populations gave them a competitive advantage if they tried to kill or displace their neighbors.

Even where the land was good for food production, as in California, deserts and mountains sometimes insulated hunter-gatherer groups and allowed their societies to last longer than their counterparts elsewhere. Farmers and herders have never displaced hunter-gatherers from a few areas that are too marginal for food production, but Diamond believes the last remaining hunter-gatherer groups on Earth will not maintain this lifestyle much longer.