The Origins of Agriculture

The Origins of Agriculture

Lecture 25

Normally, tributary rulers, tribute-taking rulers, the kings and emperors of this world, were more interested in capturing wealth than in producing it. A successful war could generate wealth much more quickly and much more effectively than investment in infrastructure.

The previous lecture de ned agriculture and explained why its impact was so revolutionary. This lecture discusses the evidence used to trace the origins of agriculture and asks why agriculture appeared. Why did humans in so many different parts of the world suddenly start getting the food and energy they needed in entirely new ways? Agriculture appeared at least 6,000 years before there were written records, so we must study it through archaeology. Rather than discussing the evidence abstractly, it may help to focus on a particular cluster of sites associated with the “Natu an” peoples, who lived in the Fertile Crescent (in modern Jordan and Israel) from about 14,000 to about 12,000 years ago. (The Fertile Crescent is a loop of highlands running from the Nile along the eastern shore of the Mediterranean, then west and south along the border between modern Iraq and Iran.)

Natu an sites are strikingly different from those of most foragers. Their dwellings were more substantial, often built into the ground for warmth, with well-built drystone walls. Natu ans hunted gazelle, but growth bands on gazelle teeth show that they did so year-round from the same place. That and the presence of rodent bones suggest they lived in their houses yearround. Other surprises include the presence of grindstones for grains such as emmer, a type of wheat, and sickles made by setting int blades into bone handles. Microscopic study of the blades shows they were used to harvest grains. In short, these look like agricultural villages.

However, by studying grain pollen, archaeologists can distinguish between wild and domesticated species, and it turns out that the Natu ans were harvesting wild grains. They were not farmers, but sedentary or semisedentary foragers. Below, we will see how study of the Natu ans has helped solve some of the puzzles that surround the “agricultural revolution.”

In Lecture Twenty-Four, we saw that agriculture appeared within a few thousand years in many different parts of the world. How can we explain this odd near-simultaneity? Let’s begin by clearing away some popular misconceptions. The rst is that extraterrestrials did it. In 2001, Stanley Kubrick hinted that aliens gave humans periodical technological nudges. This idea might explain the timing (lots of monoliths?), but historians will rightly reject it until hard evidence of aliens turns up!

More in uential has been the idea that agriculture appeared as a brilliant one-off invention, like the steam engine, whose bene ts were so obvious that it spread rapidly from a single point of origin. This is what archaeologists call a “diffusionist” view. In the 19th century, such views were popular, at least in part because they tted an imperialist view of civilization as something brought from advanced to less-advanced societies. Diffusionism in some form was the orthodox explanation for the origins of agriculture until recently. It is now rejected for several reasons.

Agriculture was not one invention but a cluster of linked innovations requiring entirely new lifeways.

Agriculture did not necessarily improve living standards, which is why many foragers who knew about farming rejected it.

Archaeological evidence suggests they may have been right, for many early farmers suffered from poor health and nutrition.

This idea encourages us to look for “push” rather than “pull” explanations, for factors that forced people to take up agriculture whether they wanted to or not.

Finally, agriculture was invented not once, but many times.

Diffusionist arguments cannot explain this odd timing, though they can help explain how agriculture then spread from a number of distinct centers.

Modern explanations include several interlocking factors. First, foragers already knew how to increase the productivity of favored species. Firestick farming was just one of many such techniques. The knowledge was there, so the problem is to explain why foragers in different parts of the world

suddenly started using such techniques more intensively. Second, the geographical distribution of easily domesticated species may help explain the geography of early farming. As Jared Diamond has pointed out, the Fertile Crescent, where the Natu ans lived, had many species like wheat, which can be domesticated with only minor changes, while other regions had species less amenable to domestication.

Third, as foragers migrated around the world, population pressure may have built up as less land was available for new migrations. Larger populations might have forced humans to use the knowledge they already had to extract more energy from a given area, to “intensify” production by introducing at least some agricultural techniques. But this argument is tricky because modern foragers often limit population growth (for example, by prolonging breast-feeding, which limits fertility, or by more violent means such as killing twins or allowing the old to die). So overpopulation should not have been a problem. Fourth, the Natu ans may help us solve this last riddle, for their population began to grow fast once they settled down. This was probably because sedentary communities, which do not have to carry the old or the very young, have less need to limit population size. But why should foragers have settled down?

The fth factor, climatic change, may help solve this puzzle. The last ice age reached its coldest stage about 20,000 years ago, and then climates began to get warmer. By 11,500 years ago, after a 1,500-year cold spell, they had reached temperatures similar to those of today. During the “interglacial” of the last 10,000 to 11,000 years, climates were generally warmer, wetter, and more stable than those of the ice ages. How might these changes have encouraged early forms of agriculture? Peter Richerson and Robert Boyd have argued that agriculture was simply impossible during the last ice age because climates were too unstable. If they are right, it is the stability of interglacial climates that explains the appearance of sustainable agriculture. Warmer and wetter climates

But for foragers sedentism can be a trap, because it may encourage population growth, making it necessary within just a few generations to start intensifying food production.

may also explain why some foragers settled down, for improved climates would have stimulated plant growth, creating regions of great abundance, or “Gardens of Eden.” Modern anthropological studies suggest that in such environments, foragers often become more sedentary. (Sedentary foragers are often described as “af uent foragers,” because they are found in regions of exceptional abundance, such as the northwestern coast of North America.) But for foragers sedentism can be a trap, because it may encourage population growth, making it necessary within just a few generations to start intensifying food production. As populations grew, sedentary foragers would soon nd it necessary to tend their crops more carefully, to water them and weed around them—in short, they would have to become farmers! In this roundabout way, pressure may have played as powerful a role in the appearance of agriculture as it did in the appearance of the rst stars!

Arguments like these work well in the Fertile Crescent. Natu ans almost certainly had a good understanding of natural plants and how they reproduced. They lived in a region with many promising potential domesticates such as wheat. We know from archaeological evidence that, as they became sedentary, populations grew rapidly. We know that warming climates may have encouraged them to become more sedentary by increasing the abundance of domesticable grains such as emmer. Finally, we know that farming villages appeared quite rapidly after a period of cooler climates (the “Younger Dryas,” c. 13,000–11,500 BP) forced sedentary foragers to start intensifying. When climates warmed again, farming villages appeared rapidly. Elsewhere, the mix of elements was different. In Mesoamerica, nomadic foragers probably cultivated crops such as early forms of maize before they became fully sedentary. There are also tantalizing hints that root crops were farmed early in coastal regions in the tropics, but we know little of these regions because most coastal sites were ooded as sea levels rose. So, though we lack a complete explanation of agricultural origins, we know many of the factors involved, even if they may have interacted in slightly different ways in different regions.

Essential Reading

Christian, Maps of Time, chap. 8. Fagan, People of the Earth, chap. 8. Ristvet, In the Beginning, chap. 2.

Supplementary Reading

Bellwood, First Farmers. Diamond, Guns, Germs, and Steel. Mithen, After the Ice.

Questions to Consider

1. How can we explain the fact that agriculture appeared within a very short time in parts of the world that had no contact with each other?

2. What can study of the Natu ans tell us about the origins of agriculture?