Given what we’ve learned about domesticated plants, there are two major obstacles to the development of agriculture: 1) humans are unwilling to experiment with domestication practices, and 2) there aren’t enough wild plants to experiment with. Diamond will focus largely on the second obstacle.
As we’ll see, the most important obstacle to the rise of agriculture is the lack of domesticable wild crops (and animals).
While there are millions of plants around the world, a surprisingly small number of them are suitable for domestication: most plants produce no fruit, and their leaves or roots are inedible. In modern times, humans haven’t succeeded in domesticating a single new plant: our ancestors worked out which crops were edible and which weren’t. Even so, crops have been domesticated in some places but not others. Some African peoples domesticated the plant sorghum, but others did not. Some peoples have access to figs and olives and domesticated both, and others had the same access, but did not domesticate them.
There is no better example of the randomness of geographic determinism than crop availability. Due to the environmental differences on the Earth’s surface, certain regions have lots of available seeds and crops and others don’t. One of Diamond’s central arguments is that the peoples with access to certain seeds and crops have formed societies that have gone on to be more powerful than societies formed by people without such resources.
The problem is that hunter-gatherer societies gradually became agricultural societies if and only if there were many available crops that could be domesticated, not just two or three. How, then, do archaeologists assess which areas of the ancient world were “suitable” for domestication, and which areas had too few crops to make agriculture practical? Diamond will try to answer his own question by examining three different regions: Mesopotamia, New Guinea, and the eastern U.S.
Mesopotamia, or the Fertile Crescent, had some important environmental advantages for early agriculturalists. The climate favored annuals, i.e., crops that sprout once a year. Annuals tend to be “mostly” edible:, a large percentage of their total mass can be consumed safely (whereas, say, a cherry tree, is almost entirely inedible—only the cherries themselves can be eaten). Mesopotamia also contained many hermaphroditic self-pollinating crops; i.e., crops that could reproduce on their own and didn’t require farmers to carefully cross-pollinate seeds every year. These crops were also protein-heavy, meaning that they could nourish human beings.
The area of Mesopotamia (which was less dry and hot thousands of years ago than it is today) had conditions that were highly favorable to the emergence of agriculture: a wide range of nutritious crops that humans could eat, enjoy, and plant easily. These conditions helped to make agriculture the most efficient and widespread form of food production in Mesopotamia, leading (Diamond suggests) to its role as the “birthplace of civilization.”
A large chunk of the world’s annual hermaphroditic crops—the crops that are easiest for farmers to domesticate and grow—are from the Fertile Crescent. Australia has a similar climate to the Fertile Crescent, but not many seeds; the same is true of Chile, California, and Southern Africa. The Fertile Crescent was the site of the earliest human agriculture because it held the greatest number of different species of plants that could be domesticated and farmed efficiently.
One of the most important advantages that Mesopotamia had as a site for agriculture was its wide range of hermaphroditic crops. Hermaphroditic crops are considerably easier to plant because they can pollinate with all other plants of the same species. So in the long run, Mesopotamia became the most important agricultural site in the world because of the availability of these species.
In early Mesopotamian civilization, people could rely on many different sources of nutrition: carbohydrates from wheat and other cereal grains, fiber and oil from flax, and protein and dairy from domesticated animals like sheep and cows (see the next chapter). With the tools of agriculture, the Fertile Crescent could produce enough nutrition to support human life.
Mesopotamian agriculture yielded a good, nutritious diet that benefited the health of the Mesopotamian agriculturalists.
Diamond notes that so far, he’s talked about why agriculture succeeded first in Mesopotamia without ever once alluding to any superiorities in Mesopotamian people. His subject is the environment, and its influence on human beings. Nevertheless, Diamond’s ideas rest upon an assumption: the ancient societies of the world had near-perfect knowledge of their environments’ plants and animals. Millennia ago, nearly all human beings had a vast knowledge of plants—which ones were poisonous, which could be planted easily, etc. Therefore, it is highly unlikely that early farmers could have ignored a wild species with potential value to them.
This section emphasizes one of the main points of Diamond’s theory of geographic determinism: that it is geographical and environmental idiosyncrasies, rather than human talent or ability, which determine the path of history. Diamond holds that all ancient peoples had essentially similar abilities—the same talent for recognizing useful crops, for example. Therefore, the real difference between Mesopotamia and, say, Australia wasn’t peoples’ intelligence or resourcefulness but rather which seeds and climate were available.
Now Diamond will contrast Mesopotamia with the eastern U.S. and New Guinea. In New Guinea, there were many reasons to pursue agriculture—there was almost no big game to hunt, for example. Agriculture developed in New Guinea around 7000 B.C., with farmers cultivating sugarcane, bananas, taro, and yams. While such crops nourished the New Guineans, there were no grains available. Also, there were no large mammals available for domestication to help with the farming (as there were in Mesopotamia). So while agriculture in New Guinea provided nutrition, it didn’t provide all the necessary nutrients.
Mesopotamian agriculture was perhaps the most successful because of the diversity of both crops and large mammals in the region—other parts of the world could sustain some agriculture, but not with the same nutritional yield as the agriculture of Mesopotamia. Agriculture became the sole source of food production in Mesopotamia sooner than it did in other regions because, nutritionally speaking, there was no need for Mesopotamians to supplement their crops with wild animals or berries.
In the eastern United States, agriculture arose around 2000 B.C.: farmers domesticated squash, sunflowers, sumpweed, and goosefoot (similar to spinach), and later knotweed, maygrass, and “little barley.” Native American crops were extremely nutritious, high in protein and oil. And yet there were major problems with the Native Americans’ diet. Sumpweed causes hay fever and skin irritation. Also, goosefoot and little barley have tiny seeds, which make them unreliable as crops—a storm could destroy them. So even though the eastern U.S. had a good climate for agriculture, it wasn’t enough: the absence of resilient crops with big seeds, annuals, and hermaphroditic self-pollinators resulted in limited agriculture.
Agriculture in the eastern United States provided considerable nutrition, but not as much nutrition as Mesopotamian agriculture (which provided protein, carbohydrates, oils, etc.). This means that the agriculturalists of the U.S. took longer to transition from hunting and gathering to agriculture, because agriculture had a slimmer comparative advantage over hunting and gathering.
The chapter ends with some caveats. First, people don’t necessarily accept better crops and livestock just because they’re more nutritious. Just because Mesopotamia had lots of useful crops available doesn’t automatically mean that it was going to foster agriculture. Still, in the long run, Mesopotamia was far more likely to develop sophisticated agriculture than either New Guinea or the eastern U.S.—and it did, sooner. Also, the “stages” of domestication that Diamond outlines (first easy annual crops like wheat, then figs and olives, etc.) aren’t set in stone. Still, civilizations will tend to go about domestication of crops in such an order (essentially, easy to difficult).
As with many other parts of his book, Diamond simplifies the history of agriculture somewhat in order to make his points, condensing the different stages of agriculture and the motives humans might have for pursuing agriculture. As with many economists, Diamond assumes a “rational market” of human agriculturalists—that is, he assumes that humans will always choose the best, healthiest, most nutritious food source—even though humans sometimes prefer food that isn’t particularly nutritious.