Some 10,000 years ago, only 5-10,000,000 people inhabited the planet, certainly no more. Our ancestors’ technology had taken them a long way, but they still lived as part of nature, not in any way as its master. They did not realize it, but the last one per cent of our existence so far would see unbelievable changes sweep across the planet and change its face forever. Humanity stood on the verge of over-running the earth with vast numbers of its species. Supporting those vast numbers was possibly the greatest revolution in our history: agriculture, the ability for people to produce their own food supply. The agricultural revolution had two parts: the domestication of plants and the domestication of livestock.
Why Eurasia and Mesopotamia?
Starting with the birth of agriculture most of history’s major developments have taken place in the vast land mass known as Eurasia and extending across the Mediterranean and North Africa. Europeans who dominated the globe in the late 1800s and early 1900s claimed religious, cultural, and even biological superiority as the basis for their predominance. While such ideas hold little favor today, there still remains the question of why Asia and Europe have held central place in the history of civilization. Much of the answer probably rests in geographic and biological factors.
The underlying factor is that Eurasia lies along an East-West axis in mostly temperate zones. In contrast, Africa and the Americas are oriented from north to south and thus straddle a variety of climates. As a result, crops found in Eurasia are more adapted to the same diseases, climate, and seasonal variations in sunlight (which determine when plants germinate, flower, and bear fruit). Therefore, domesticated crops and intensive agriculture can spread more rapidly across Eurasia than they can across the vastly different climactic zones in Africa and the Americas. For example, because of intervening tropical zones, the cultivation of corn in the Temperate Zone of Mexico in the northern hemisphere never spread to Peru in the southern hemisphere until after 1500 when Europeans conquered both regions. Similarly, crops adapted for temperate zones in northern parts of Africa did not reach the southern tip of Africa until Dutch settlers introduced them in the 1600s.
Of course, there are also topographical and even climactic barriers within Eurasia, such as the Tibetan Plateau, Himalayan Mountains, and Asian steppes isolating East Asia from the rest of Eurasia. Therefore, agriculture probably developed independently in China and spread from there to Southeast Asia, Korea, and Japan. However, despite topographical barriers, the similar climates of East Asia and the western half of Eurasia ultimately allowed crop sharing in both directions, thus helping both civilizations advance more quickly.
More specifically, it was Mesopotamia (modern Iraq) where agriculture first evolved in Eurasia and then spread westward across North Africa and Europe and eastward to the Indus River Valley. Environmental factors favored this specific region as the birthplace of agriculture. First of all, Mesopotamia, and the Middle East in general, have cool rainy winters and hot dry summers, encouraging plants, especially cereals, to develop large seeds for rapid growth in the limited growing season. This produces relatively small plants without woody stems, which, in turn leads to cereals with lots of large seeds (i.e., more food) that are easy to harvest (without woody stems).
Another factor is that Mesopotamia has many self-pollinating crops (six of them exclusive to that area) that can reproduce without pollination with other plants. The importance here is that recessive traits that are vital to farming but harmful to the plant in nature do not get bred out of the plant through cross-pollination. For example, along with the dominant trait for grains and pea pods to shatter in order to spread their seeds is a recessive trait for a few plants not to shatter. This made it easier for people to harvest them, plant more of them next season, and spread the varieties with the normally harmful tendency not to shatter.
Along with the spread of agriculture from Mesopotamia, other ideas and technologies could spread as well, leading to the relatively rapid development and spread of civilization across Eurasia compared to other regions of the globe whose environments prevented or greatly slowed down such exchanges. And, of course, after the impetus started by Mesopotamia, the exchange of new ideas became two-way, further accelerating the rise and spread of civilization in Eurasia.
The invention of agriculture
In addition to factors unique to Mesopotamia,two other converging factors led to the domestication of plants. First, better hunting and gathering technology provided a more stable food supply. Second, warmer and wetter conditions in the Near East at the end of the last Ice Age about 10,000 years ago led to the spread of cereal grains. Together these provided more stable food supplies that allowed people to settle down in more permanent villages. These villages produced two very different effects that together helped lead to the discovery and triumph of agriculture.
One was a growing population that needed more food than the hunting and gathering lifestyle could supply. This may have been partly due to earlier weaning of the young. Since women in hunting and gathering societies were always on the move, they could deal with only one highly dependent child at a time. Therefore, so they have only one small child to carry at a time, they would nurse their young up to age four to interrupt their fertility until their youngest child was less dependent on the mother. More settled village life made such strict birth control less mandatory, allowing earlier weaning and a higher birth rate as a result.
Settled village life also was gave people the opportunity to watch seeds in one place for a long time and notice how seeds grow into plants. Exactly how and when this happened is not known, but women probably made this discovery since they gathered the seeds and had more opportunity to notice how they sprouted and grew. Possible scenarios of this discovery include seeds spilled near camp or a wet grain supply sprouting and growing. However it happened, the realization of the potential of this discovery was probably gradual.
So was the transition to a completely settled agricultural lifestyle. While later civilizations would see agriculture as a gift of the gods, hunting and gathering peoples, such as the early Hebrews quoted above, saw it as a curse since it involved much more work and went against the traditional ways of life they had followed for countless generations. Whereas tradition today is generally shoved aside and scorned, we should keep in mind that until very recently, it was a major force in people’s lives. They did not take change so lightly as we do since it disrupted the fragile stability of their lives. So the question arises as to why did people turn to farming.
The most likely explanation was they had to. For a long time after the discovery of agriculture, people continued to follow a hunting and gathering lifestyle mixed in with some casual agriculture, such as scattering seeds along a riverbank or in a field and coming back in a few months to harvest it. This did improve the food supply, and dramatically increased the number of people that could be supported. Even the primitive agriculture practiced then could support up to fifty times more people than hunting and gathering could. However, those extra people put a growing strain on the natural environment’s ability to feed them. One solution was to expand the agriculture. Of course, that led to more food and more population, causing even more strain on the natural food supply and leading to further expansion of the agriculture. In time, both men and women had to devote more and more time to tending the crops and less time to their traditional hunting and gathering ways. Eventually, they settled down and became full-time farmers.
Settled agricultural life had dramatic effects on human society and the environment. First of all, farming required less cooperation and sharing than hunting and gathering did. Before, all members of a tribe had to hunt together and share the results. Since there was no private property or anything to fight over, hunting and gathering societies were (and still are) relatively peaceful and harmonious. In contrast, agriculture allowed individual families to farm their own lands. As a result, private property evolved which led to social classes and more conflict in society between rich and poor.
New agricultural techniques, which replaced the more primitive slash and burn agriculture, also had their effects. The two-field system, which left one field fallow each year to replenish the soil, and crop rotation, which used different crops to take different nutrients out of the soil, reduced soil exhaustion. Both of these, combined with one other technique, irrigation, also created a surplus of grain and the need for a high degree of organization and cooperation. That surplus and level of organization in turn would lead to the rise of the first cities and civilizations with specialized crafts and technologies such as writing and metallurgy.
In the process of farming, our ancestors also inadvertently disrupted natural selection. There were two varieties of wheat they collected on the hillsides of the Near East. The dominant type shattered upon the slightest touch, scattering the seeds so the species could spread and survive. The other, recessive type, did not scatter its seeds so easily, and thus was harder to find. However, it was easier to harvest since the seeds did not scatter. As a result, a higher proportion of this variety was collected and planted than occurred in nature. With each succeeding year a higher proportion of the non-scattering wheat was harvested and planted. Natural selection had been reversed.