Agriculture: Why and How Did It Begin?

Today the world’s population exceeds 6000 million people, almost all of whom depend on agriculture for their survival, and yet growing crops and raising domestic animals is a very recent development in the history of humanity.

Anatomically modern humans Homo sapiens began to colonize the continents as foraging hunter-fisher-gatherers some 100,000 years ago, but it was not until about 12,000 years ago that farming began to replace foraging as the main mode of human subsistence. It did so first, and very gradually, in the so-called Fertile Crescent of Southwest Asia.

Primary (independent) transitions from foraging to farming occurred in other parts of the world, including central China, northern tropical Africa, and Mesoamerica, even later than in Southwest Asia, but by 1500 A.D., when Europeans began to expand overseas, most of the world's population (estimated at 350 million) had become reliant on agriculture.

It prompts the question, why did it not occur much earlier, or, conversely, why did humans remain dependent on hunting, fishing, and gathering for so long? This response stems from a deeply embedded and still prevalent assumption that the transition to agriculture was an inevitable stage in human progress. However, in the long perspective of humanity’s foraging past the question that demands an answer is not why did agriculture not develop sooner, but why did it develop at all?

Before pursuing that question, we need to consider what precisely is meant by ‘‘agriculture,’’ because failure to define it, and other related terms such as cultivation and domestication, has led to confusion in attempts to explain why and how agriculture arose. Here, cultivation is defined as the sowing or planting, tending, and harvesting of useful domesticated or wild plants, which may or may not involve tilling the soil.

Domestication is defined as the genetic physiological, and/or morphological alteration of wild plants that results from deliberate or inadvertent cultural selection and leads to the plants’ dependence on humans for their long-term survival.

Agriculture is defined as the growing of domesticated crops by methods of cultivation that usually but not always involve systematic tillage of the soil. The distinction between cultivation and agriculture is particularly important because it enables us to differentiate between systems of crop production practiced by farmers and systems of wild-plant production practiced by foragers.

Having clarified this distinction, we need next to consider how foragers have cultivated wild plants to enhance their productivity.

PLANT CULTIVATION BY FORAGERS

Many historical and ethnographic accounts of ‘‘hunter gatherers’’ show that they not only gathered wild plants but often increased the productivity of selected taxa by such methods as controlled burning; vegetation clearance and weeding; harvesting, storing, sowing, and planting seeds, tubers, cuttings, and other propagules; and tilling, draining, and irrigating the soil.

Such practices can be regarded as forms of cultivation, but, although they are sometimes described as ‘‘protoagricultural,’’ they do not amount to agriculture (as here defined) because they rarely include fully domesticated crops.

This distinction is not just se- mantic, because the ethnographic, historical, and more limited archaeological evidence we have indicates that cultivation by foragers was usually only a minor activity in their hunting,fishing,gathering systems of subsistence.

Although many forager groups engaged in small-scale cultivation, it did not normally, and certainly not inevitably, lead to full plant domestication and the develop- ment of agriculture. However, that this did occasionally occur is undeniable, for if it had not, agriculture would never have arisen.

So, what factors may have caused specific forager groups to devote more time and effort to cultivation, and to become increasingly reliant on a suite of plants that were domesticated and transformed into agricultural crops for food and other products, thereby initiating primary transitions from foraging to farming?