Dirt: The Erosion of Civilizations - Kootenay Local Agricultural Society

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For much of the last century, theories for the origin of agriculture
emphasized the competing oasis and cultural evolution hypotheses. The
oasis hypothesis held that the postglacial drying of the Middle East
restricted edible plants, people, and other animals to well-watered floodplains.
This forced proximity bred familiarity, which eventually led to
domestication. In contrast, the cultural evolution hypothesis holds that
regional environmental change was unimportant in the gradual adoption
of agriculture through an inevitable progression of social development.
Unfortunately, neither hypothesis provides satisfying answers for why agriculture
arose when and where it did.
A fundamental problem with the oasis theory is that the wild ancestors
of our modern grains came to the Middle East from northern Africa at the
end of the last glaciation. This means that the variety of food resources
available to people in the Middle East was expanding at the time that agriculture
arose—the opposite of the oasis theory. So the story cannot be as
simple as the idea that people, plants, and animals crowded into shrinking
oases as the countryside dried. And because only certain people in the
Middle East adopted agriculture, the cultural adaptation hypothesis falls
short. Agriculture was not simply an inevitable stage on the road from
hunting and gathering to more advanced societies.
The transition to an agricultural society was a remarkable and puzzling
behavioral adaptation. After the peak of the last glaciation, people herded
gazelles in Syria and Israel. Subsisting on these herds required less effort
than planting, weeding, and tending domesticated crops. Similarly, in Central
America several hours spent gathering wild corn could provide food for
a week. If agriculture was more difficult and time-consuming than hunting
and gathering, why did people take it up in the first place?
Increasing population density provides an attractive explanation for the
origin and spread of agriculture. When hunting and gathering groups grew
beyond the capacity of their territory to support them, part of the group
would split off and move to new territory. Once there was no more productive
territory to colonize, growing populations developed more intensive
(and time-consuming) ways to extract a living from their environment.
Such pressures favored groups that could produce food themselves
to get more out of the land. In this view, agriculture can be understood as
a natural behavioral response to increasing population.
Modern studies have shown that wild strains of wheat and barley can be
readily cultivated with simple methods. Although this ease of cultivation
suggests that agriculture could have originated many times in many places,
rivers of life