My other example of how ancient peoples apparently used their ethnobiological knowledge to good effect comes from the Jordan Valley in the ninth millennium B.C., the period of the earliest crop cultivation there. The valley’s first domesticated cereals were barley and emmer wheat, which are still among the world’s most productive crops today. But, as at Tell Abu Hureyra, hundreds of other seed-bearing wild plant species must have grown in the vicinity, and a hundred or more of them would have been edible and gathered before the rise of plant domestication. What was it about barley and emmer wheat that caused them to be the first crops? Were those first Jordan Valley farmers botanical ignoramuses who didn’t know what they were doing? Or were barley and emmer wheat actually the best of the local wild cereals that they could have selected?
Two Israeli scientists, Ofer Bar-Yosef and Mordechai Kislev, tackled this question by examining the wild grass species still growing wild in the valley today. Leaving aside species with small or unpalatable seeds, they picked out 23 of the most palatable and largest-seeded wild grasses. Not surprisingly, barley and emmer wheat were on that list.
But it wasn’t true that the 21 other candidates would have been equally useful. Among those 23, barley and emmer wheat proved to be the best by many criteria. Emmer wheat has the biggest seeds and barley the second biggest. In the wild, barley is one of the 4 most abundant of the 23 species, while emmer wheat is of medium abundance. Barley has the further advantage that its genetics and morphology permit it to evolve quickly the useful changes in seed dispersal and germination inhibition that we discussed in the preceding chapter. Emmer wheat, however, has compensating virtues: it can be gathered more efficiently than barley, and it is unusual among cereals in that its seeds do not adhere to husks. As for the other 21 species, their drawbacks include smaller seeds, in many cases lower abundance, and in some cases their being perennial rather than annual plants, with the consequence that they would have evolved only slowly under domestication.
Thus, the first farmers in the Jordan Valley selected the 2 very best of the 23 best wild grass species available to them. Of course, the evolutionary changes (following cultivation) in seed dispersal and germination inhibition would have been unforeseen consequences of what those first farmers were doing. But their initial selection of barley and emmer wheat rather than other cereals to collect, bring home, and cultivate would have been conscious and based on the easily detected criteria of seed size, palatability, and abundance.
This example from the Jordan Valley, like that from Tell Abu Hureyra, illustrates that the first farmers used their detailed knowledge of local species to their own benefit. Knowing far more about local plants than all but a handful of modern professional botanists, they would hardly have failed to cultivate any useful wild plant species that was comparably suitable for domestication.
WE CAN NOW examine what local farmers, in two parts of the world (New Guinea and the eastern United States) with indigenous but apparently deficient food production systems compared to that of the Fertile Crescent, actually did when more-productive crops arrived from elsewhere. If it turned out that such crops did not become adopted for cultural or other reasons, we would be left with a nagging doubt. Despite all our reasoning so far, we would still have to suspect that the local wild flora harbored some ancestor of a potential valuable crop that local farmers failed to exploit because of similar cultural factors. These two examples will also demonstrate in detail a fact critical to history: that indigenous crops from different parts of the globe were not equally productive.
New Guinea, the largest island in the world after Greenland, lies just north of Australia and near the equator. Because of its tropical location and great diversity in topography and habitats, New Guinea is rich in both plant and animal species, though less so than continental tropical areas because it is an island. People have been living in New Guinea for at least 40,000 years—much longer than in the Americas, and slightly longer than anatomically modern peoples have been living in western Europe. Thus, New Guineans have had ample opportunity to get to know their local flora and fauna. Were they motivated to apply this knowledge to developing food production?
I mentioned already that the adoption of food production involved a competition between the food producing and the hunting-gathering lifestyles. Hunting-gathering is not so rewarding in New Guinea as to remove the motivation to develop food production. In particular, modern New Guinea hunters suffer from the crippling disadvantage of a dearth of wild game: there is no native land animal larger than a 100-pound flightless bird (the cassowary) and a 50-pound kangaroo. Lowland New Guineans on the coast do obtain much fish and shellfish, and some lowlanders in the interior still live today as hunter-gatherers, subsisting especially on wild sago palms. But no peoples still live as hunter-gatherers in the New Guinea highlands; all modern highlanders are instead farmers who use wild foods only to supplement their diets. When highlanders go into the forest on hunting trips, they take along garden-grown vegetables to feed themselves. If they have the misfortune to run out of those provisions, even they starve to death despite their detailed knowledge of locally available wild foods. Since the hunting-gathering lifestyle is thus nonviable in much of modern New Guinea, it comes as no surprise that all New Guinea highlanders and most lowlanders today are settled farmers with sophisticated systems of food production. Extensive, formerly forested areas of the highlands were converted by traditional New Guinea farmers to fenced, drained, intensively managed field systems supporting dense human populations.
Archaeological evidence shows that the origins of New Guinea agriculture are ancient, dating to around 7000 B.C. At those early dates all the landmasses surrounding New Guinea were still occupied exclusively by hunter-gatherers, so this ancient agriculture must have developed independently in New Guinea. While unequivocal remains of crops have not been recovered from those early fields, they are likely to have included some of the same crops that were being grown in New Guinea at the time of European colonization and that are now known to have been domesticated locally from wild New Guinea ancestors. Foremost among these local domesticates is the modern world’s leading crop, sugarcane, of which the annual tonnage produced today nearly equals that of the number two and number three crops combined (wheat and corn). Other crops of undoubted New Guinea origin are a group of bananas known as Australimusa bananas, the nut tree Canarium indicum, and giant swamp taro, as well as various edible grass stems, roots, and green vegetables. The breadfruit tree and the root crops yams and (ordinary) taro may also be New Guinean domesticates, although that conclusion remains uncertain because their wild ancestors are not confined to New Guinea but are distributed from New Guinea to Southeast Asia. At present we lack evidence that could resolve the question whether they were domesticated in Southeast Asia, as traditionally assumed, or independently or even only in New Guinea.
However, it turns out that New Guinea’s biota suffered from three severe limitations. First, no cereal crops were domesticated in New Guinea, whereas several vitally important ones were domesticated in the Fertile Crescent, Sahel, and China. In its emphasis instead on root and tree crops, New Guinea carries to an extreme a trend seen in agricultural systems in other wet tropical areas (the Amazon, tropical West Africa, and Southeast Asia), whose farmers also emphasized root crops but did manage to come up with at least two cereals (Asian rice and a giant-seeded Asian cereal called Job’s tears). A likely reason for the failure of cereal agriculture to arise in New Guinea is a glaring deficiency of the wild starting material: not one of the world’s 56 largest-seeded wild grasses is native there.
Second, the New Guinea fauna included no domesticable large mammal species whatsoever. The sole domestic animals of modern New Guinea, the pig and chicken and dog, arrived from Southeast Asia by way of Indonesia within the last several thousand years. As a result, while New Guinea lowlanders obtain protein from the fish they catch, New Guinea highland farmer populations suffer from severe protein limitation, because the staple
crops that provide most of their calories (taro and sweet potato) are low in protein. Taro, for example, consists of barely 1 percent protein, much worse than even white rice, and far below the levels of the Fertile Crescent’s wheats and pulses (8–14 percent and 20–25 percent protein, respectively).
Children in the New Guinea highlands have the swollen bellies characteristic of a high-bulk but protein-deficient diet. New Guineans old and young routinely eat mice, spiders, frogs, and other small animals that peoples elsewhere with access to large domestic mammals or large wild game species do not bother to eat. Protein starvation is probably also the ultimate reason why cannibalism was widespread in traditional New Guinea highland societies.
Finally, in former times New Guinea’s available root crops were limiting for calories as well as for protein, because they do not grow well at the high elevations where many New Guineans live today. Many centuries ago, however, a new root crop of ultimately South American origin, the sweet potato, reached New Guinea, probably by way of the Philippines, where it had been introduced by Spaniards. Compared with taro and other presumably older New Guinea root crops, the sweet potato can be grown up to higher elevations, grows more quickly, and gives higher yields per acre cultivated and per hour of labor. The result of the sweet potato’s arrival was a highland population explosion. That is, even though people had been farming in the New Guinea highlands for many thousands of years before sweet potatoes were introduced, the available local crops had limited them in the population densities they could attain, and in the elevations they could occupy.
In short, New Guinea offers an instructive contrast to the Fertile Crescent. Like hunter-gatherers of the Fertile Crescent, those of New Guinea did evolve food production independently. However, their indigenous food production was restricted by the local absence of domesticable cereals, pulses, and animals, by the resulting protein deficiency in the highlands, and by limitations of the locally available root crops at high elevations. Yet New Guineans themselves know as much about the wild plants and animals available to them as any peoples on Earth today. They can be expected to have discovered and tested any wild plant species worth domesticating. They are perfectly capable of recognizing useful additions to their crop larder, as is shown by their exuberant adoption of the sweet potato when it arrived. That same lesson is being driven home again in New Guinea today, as those tribes with preferential access to introduced new crops and livestock (or with the cultural willingness to adopt them) expand at the expense of tribes without that access or willingness. Thus, the limits on indigenous food production in New Guinea had nothing to do with New Guinea peoples, and everything with the New Guinea biota and environment.
OUR OTHER EXAMPLE of indigenous agriculture apparently constrained by the local flora comes from the eastern United States. Like New Guinea, that area supported independent domestication of local wild plants. However, early developments are much better understood for the eastern United States than for New Guinea: the crops grown by the earliest farmers have been identified, and the dates and crop sequences of local domestication are known. Well before other crops began to arrive from elsewhere, Native Americans settled in eastern U.S. river valleys and developed intensified food production based on local crops. Hence they were in a position to take advantage of the most promising wild plants. Which ones did they actually cultivate, and how did the resulting local crop package compare with the Fertile Crescent’s founder package?
It turns out that the eastern U.S. founder crops were four plants domesticated in the period 2500–1500 B.C., a full 6,000 years after wheat and barley domestication in the Fertile Crescent. A local species of squash provided small containers, as well as yielding edible seeds. The remaining three founders were grown solely for their edible seeds (sunflower, a daisy relative called sumpweed, and a distant relative of spinach called goosefoot).
But four seed crops and a container fall far short of a complete food production package. For 2,000 years those founder crops served only as minor dietary supplements while eastern U.S. Native Americans continued to depend mainly on wild foods, especially wild mammals and waterbirds, fish, shellfish, and nuts. Farming did not supply a major part of their diet until the period 500–200 B.C., after three more seed crops (knotweed, maygrass, and little barley) had been brought into cultivation.
A modern nutritionist would have applauded those seven eastern U.S.crops. All of them were high in protein—17–32 percent, compared with 8–14 percent for wheat, 9 percent for corn, and even lower for barley and white rice. Two of them, sunflower and sumpweed, were also high in oil (45–47 percent). Sumpweed, in particular, would have been a nutritionist’s ultimate dream, being 32 percent protein and 45 percent oil. Why aren’t we still eating those dream foods today?
Alas, despite their nutritional advantage, most of these eastern U.S. crops suffered from serious disadvantages in other respects. Goosefoot, knotweed, little barley, and maygrass had tiny seeds, with volumes only one-tenth that of wheat and barley seeds. Worse yet, sumpweed is a wind-pollinated relative of ragweed, the notorious hayfever-causing plant. Like ragweed’s, sumpweed’s pollen can cause hayfever where the plant occurs in abundant stands. If that doesn’t kill your enthusiasm for becoming a sumpweed farmer, be aware that it has a strong odor objectionable to some people and that handling it can cause skin irritation.
Mexican crops finally began to reach the eastern United States by trade routes after A.D. 1. Corn arrived around A.D. 200, but its role remained very minor for many centuries. Finally, around A.D. 900 a new variety of corn adapted to North America’s short summers appeared, and the arrival of beans around A.D. 1100 completed Mexico’s crop trinity of corn, beans, and squash. Eastern U.S. farming became greatly intensified, and densely populated chiefdoms developed along the Mississippi River and its tributaries. In some areas the original local domesticates were retained alongside the far more productive Mexican trinity, but in other areas the trinity replaced them completely. No European ever saw sumpweed growing in Indian gardens, because it had disappeared as a crop by the time that European colonization of the Americas began, in A.D. 1492. Among all those ancient eastern U.S. crop specialties, only two (sunflower and eastern squash) have been able to compete with crops domesticated elsewhere and are still grown today. Our modern acorn squashes and summer squashes are derived from those American squashes domesticated thousands of years ago.
Thus, like the case of New Guinea, that of the eastern United States is instructive. A priori, the region might have seemed a likely one to support productive indigenous agriculture. It has rich soils, reliable moderate rainfall, and a suitable climate that sustains bountiful agriculture today. The flora is a species-rich one that includes productive wild nut trees (oak and hickory). Local Native Americans did develop an agriculture based on local domesticates, did thereby support themselves in villages, and even developed a cultural florescence (the Hopewell culture centered on what is today Ohio) around 200 B.C.-A.D. 400. They were thus in a position for several thousand years to exploit as potential crops the most useful available wild plants, whatever those should be.
Nevertheless, the Hopewell florescence sprang up nearly 9,000 years after the rise of village living in the Fertile Crescent. Still, it was not until after A.D. 900 that the assembly of the Mexican crop trinity triggered a larger population boom, the so-called Mississippian florescence, which produced the largest towns and most complex societies achieved by Native Americans north of Mexico. But that boom came much too late to prepare Native Americans of the United States for the impending disaster of European colonization. Food production based on eastern U.S. crops alone had been insufficient to trigger the boom, for reasons that are easy to specify. The area’s available wild cereals were not nearly as useful as wheat and barley. Native Americans of the eastern United States domesticated no locally available wild pulse, no fiber crop, no fruit or nut tree. They had no domesticated animals at all except for dogs, which were probably domesticated elsewhere in the
Americas.
It’s also clear that Native Americans of the eastern United States were not overlooking potential major crops among the wild species around them. Even 20th-century plant breeders, armed with all the power of modern science, have had little success in exploiting North American wild plants. Yes, we have now domesticated pecans as a nut tree and blueberries as a fruit, and we have improved some Eurasian fruit crops (apples, plums, grapes, raspberries, blackberries, strawberries) by hybridizing them with North American wild relatives. However, those few successes have changed our food habits far less than Mexican corn changed food habits of Native Americans in the eastern United States after A.D. 900.
The farmers most knowledgeable about eastern U.S. domesticates, the region’s Native Americans themselves, passed judgment on them by discarding or deemphasizing them when the Mexican trinity arrived. That outcome also demonstrates that Native Americans were not constrained by cultural conservativism and were quite able to appreciate a good plant when they saw it. Thus, as in New Guinea, the limitations on indigenous food production in the eastern United States were not due to Native American peoples themselves, but instead depended entirely on the American biota and environment.
WE HAVE NOW considered examples of three contrasting areas, in all of which food production did arise indigenously. The Fertile Crescent lies at one extreme; New Guinea and the eastern United States lie at the opposite extreme. Peoples of the Fertile Crescent domesticated local plants much earlier. They domesticated far more species, domesticated far more productive or valuable species, domesticated a much wider range of types of crops, developed intensified food production and dense human populations more rapidly, and as a result entered the modern world with more advanced technology, more complex political organization, and more epidemic diseases with which to infect other peoples.