Chapter 9 Chapter 8: Apples or Indians?

We have just seen how people in certain regions began to cultivate wild plants.It was a major, unforeseen step for the way these people lived and for their place in history for future generations.Now, let's go back to our original question: Why didn't agriculture emerge independently in some fertile and well-suited areas, such as California, Europe, temperate Australia, and subequatorial Africa?And among those areas where agriculture emerged independently, why did some areas develop agriculture much earlier than others? This brings us to two contrasting explanations: a problem with local people, or a problem with locally available wild plants.On the one hand, perhaps almost any well-watered, temperate region of the globe, or the tropics, has enough wild plant species suitable for domestication; The explanation may lie in the ethnic cultural characteristics of the people in these areas.On the other hand, perhaps in any large area of ​​the globe at least some peoples may have been readily receptive to the experiments leading to domestication.Therefore, only the lack of suitable wild plants can explain why food production did not develop in some areas.

As we shall see in the next chapter, the corresponding problem of the domestication of large wild mammals proved to be relatively easy to solve, because there are far fewer species of them than plants.There are only about 148 species of large wild mammalian terrestrial herbivores or omnivores in the world, and they are large mammals that can be considered potentially domesticated.There are only a few factors that determine whether a mammal is suitable for domestication.The straightforward approach, therefore, is to examine the large mammals of an area and analyze whether the lack of domestication of mammals in some areas is due to the unavailability of suitable wild species rather than to local people.

It may be much more difficult to apply this approach to plants, because the number of plants is too large, there are 200,000 species of wild flowering plants alone, which occupy the first place among land plants and are the basis of almost all our crops. source.Even in a limited area like California, we cannot hope to examine all the wild animals and assess how much of them are domesticable.However, we can now take a look at how this problem is solved. If someone hears that there are so many kinds of flowering plants, his first reaction may be this: since there are so many kinds of wild plants on the earth, as long as there is a good enough climate, wild plants must be abundant. Sufficient to provide a large number of candidate plant varieties for breeding crops.

But if that's the case, consider that most wild plants are not suitable for obvious reasons: they are woody plants, they don't produce any edible fruit, and their leaves and roots are inedible.Of these 200,000 species of wild plants, only a few thousand are available for human consumption, and only a few hundred have been more or less domesticated.Even among these hundreds of crops, most were minor additions to our diets, not enough on their own to support the rise of civilization.The output of only a dozen kinds of crops has accounted for more than 80% of the total annual output of all crops in the modern world.These dozen or so amazing crops are wheat, maize, rice, barley and sorghum among cereals; soybeans among legumes; potatoes, cassava and sweet potatoes among roots or tubers; sugar cane and sugar beets among sugar crops and fruits of bananas.Cereal crops alone now account for more than half of the calories consumed by the world's population.With so few staple crops in the world, all of which were domesticated thousands of years ago, it is not surprising that many regions of the world simply never had any native wild plants of significant potential.The fact that we have not been able to domesticate even a new important food plant in modern times suggests that ancient people may have indeed explored nearly all useful wild plants and domesticated all that were worth domesticating.

Yet the failure to domesticate wild plants in some parts of the world remains elusive.The most obvious example of this is when some plants are domesticated in one area but not in another.So we can be sure that it is indeed possible to breed a wild plant into a useful crop, but we must also ask: Why is that wild plant not domesticated in some areas? A classic example of confusion comes to Africa.The important grain sorghum was domesticated in the Sahel along the southern edge of the Sahara Desert in Africa.Wild sorghum also exists as far south as southern Africa, but neither sorghum nor any other plant was cultivated in southern Africa until 2,000 years ago, when the Bangu farmers introduced a whole crop from regions of Africa north of the equator.Why didn't the natives of southern Africa domesticate sorghum for themselves?

Equally perplexing is the failure to domesticate wild flax in western Europe and North Africa, or wild einkorn in the southern Balkans.Since these two plants belonged to the first eight major crops in the Fertile Crescent, they should also be the two most easily domesticated plants among all wild plants.Immediately after their introduction from the Fertile Crescent with overall food production, they were cultivated in these wild habitats outside the Fertile Crescent.So why didn't some groups in these remote areas take the initiative to grow them? Likewise, the four earliest domesticated fruits of the Fertile Crescent have wild habitats as far as the eastern Mediterranean, where they appear to have been first domesticated: olives, grapes, and figs appear westward in Italy, Spain, and Northwest Africa, and jujubes Coconut trees spread throughout North Africa and the Arabian Peninsula.These four fruits are by far the easiest of all wild fruits to domesticate.Why, then, did some populations of the Fertile Crescent fail to domesticate them, and only cultivated them after they had been domesticated in the Eastern Mediterranean and introduced as crops from there?

Other striking examples involve wild plants that were not domesticated in areas where food production never arose spontaneously, although they have close relatives that were domesticated elsewhere.For example, the European olive was domesticated in the eastern Mediterranean region.There are about 40 species of olives in tropical Africa, southern Africa, southern Asia and eastern Australia, some of which are close relatives of the European olive, but none have been domesticated.Likewise, although one species of wild apple and wild grape was domesticated in Eurasia, there are many related wild apples and wild grapes in North America, some of which have been combined in modern times with wild apples and wild grapes from Eurasia. Grapes were crossed to improve varieties of these crops.So why didn't Native Americans themselves domesticate these apparently useful apples and grapes?

Such examples can be said to be numerous.But this reasoning has a fatal flaw: plant domestication is not a matter of hunter-gatherers domesticating a plant or continuing their nomadic lives.Assuming that as long as hunter-gatherer Indians settled down and cultivated wild apples, the North American wild apple would indeed have evolved into a remarkable crop.But it is unlikely that nomadic hunter-gatherers will abandon their traditional ways of life, settle in villages, and start tending apple orchards, unless there are many other domesticable plants and animals available to sedentary food producers. The way of life can compete with that of hunter-gatherer.

In summary, how do we assess the likelihood of domestication of an entire flora in a region?For these Indians who failed to domesticate North American apples, was the question really the Indians or the apples? To answer this question, we can compare 3 regions at opposite extremes in independent centers of domestication.As we have seen, one such region is the Fertile Crescent, perhaps the world's earliest center of food production and home to several of the modern world's major crops and nearly all major domesticated animals.The other two regions are New Guinea and the Eastern United States.Both regions did domesticate native crops, but few of these crop varieties, only one became world important, and the resulting food as a whole failed to aid human technology and administration as it did in the Fertile Crescent. Broad development of the organization.In light of this comparison, we might as well ask: Do the flora and environments of the Fertile Crescent have clear advantages over those of New Guinea and the eastern United States?

One of the major facts of human history is the importance of the region of Southwest Asia called the Fertile Crescent (so named for its crescent-shaped elevation on the map, see Figure 8.1) in early human development.That region seemed to be the site of a whole new chain of developments, including cities, writings, empires, and what we call civilization, for better or worse.And all these new conditions, made possible by dense populations, by stores of surplus food, and by the ability to support specialized men who were not engaged in agriculture, were made possible by the advent of crop cultivation. Food production in the form of food and livestock raising.Food production was the first of those important new things to emerge in the Fertile Crescent.So if one wants to understand the origins of the modern world, one must take seriously the question of why the Fertile Crescent's domesticated plants and animals gave it such a strong head start.

Fortunately, the Fertile Crescent is by far the most well-studied and best-understood region on Earth when it comes to the rise of agriculture.For most crops domesticated in or near the Fertile Crescent, the wild ancestor has been identified; the close relationship of the wild ancestor to the crop has been demonstrated by genetic and chromosomal studies; the geographic distribution of the wild ancestor has been established changes in the wild ancestors under domestication conditions have been identified and are often understood as single genes; these changes can be seen in successive accumulations of the archaeological record; and the approximate place and time of domestication are known. clear.I do not deny that some other areas, notably China, also had favorable conditions as sites of early domestication, but for the Fertile Crescent these favorable conditions and the resulting crop development can be studied in much more detail illustrate. One advantage of the Fertile Crescent: It's in the so-called Mediterranean climate zone, a climate characterized by mild, wet winters and long, hot, dry summers.Plants grown in this climate must be able to survive the long dry season and quickly return to growth when the rainy season arrives.Many plants in the Fertile Crescent, especially cereals and legumes, have adapted to the local environment to become useful to humans: they are annuals, which means that the plants themselves wither and die during the dry season. With only one year of life, annuals are necessarily dwarf herbaceous plants.Many of them devote a large part of their energy to producing large seeds that lie dormant during the dry season and are ready to germinate when the rainy season comes.Thus, annuals don't waste energy growing inedible xylem or fibrous stalks like the branches of trees and shrubs.But many large-grained seeds, mainly of annual cereals and legumes, are edible for human consumption.They make up 6 of the 12 major crops of the modern world.In contrast, if you live next to a forest and look out of the window, the plants you see tend to be trees and shrubs, most of which have inedible branches and little energy. Spend to produce edible seeds.Of course, some trees in forests in humid climates do produce large, edible seeds, but these seeds have not been adapted to survive long dry seasons and are therefore unsuitable for long-term storage by humans. Another advantage of the Fertile Crescent flora: The wild progenitors of many Fertile Crescent crops were already lush and productive, and their value must have been obvious to hunter-gatherers in large swaths.Botanists have conducted some experimental studies collecting seeds from natural large patches of wild grains, as hunter-gatherers did more than 10,000 years ago.These studies show that nearly one ton of seeds can be harvested per hectare per year, yielding 50 calories of food energy for just one calorie of labor.Some hunter-gatherers of the Fertile Crescent gathered large quantities of wild plants during the short time that the seeds were ripe and stored them as food for the rest of the year, thus growing the plants before they even started cultivating them. Settled down in a permanent lining. Because the Fertile Crescent grains were already so prolific in the wild, little else had been changed by cultivation.As we have discussed in the previous chapter, the major changes—the disruption of the natural mechanisms of seed dispersal and germination inhibition—came into being automatically and rapidly as soon as humans began planting seeds in fields.The wild ancestors of our present wheat and barley crops were so similar in appearance to the crops themselves that we have never had any doubts about their wild ancestors.Because domestication was so easy, the large-seeded annual plant was or was one of the first crops developed not only in the Fertile Crescent but also in China and the Sahel. Contrast this rapid evolution of wheat and barley with that of maize, the leading New World cereal.The probable ancestor of maize is a wild plant called teosinte, which has a seed and flower structure so different that botanists have long debated whether it was the ancestor of maize.The food value of teosinte may not have impressed hunter-gatherers: it was less productive in the wild than wild wheat, and it produced far fewer seeds than the corn that eventually evolved from it, and its seeds It was also covered with an inedible hard shell.For teosinte to be a useful crop, it had to undergo drastic changes in its reproductive biology to greatly increase the number of seeds and shed those hard, rock-like shells on the seeds.Archaeologists are still hotly debating exactly how many centuries or millennia it took for the ancient cob of corn to grow from the size of a tiny bit to the size of a human thumb during the development of crops in the Americas, but one thing seems clear Yes, that is, it took thousands of years for them to reach their modern size. —The disparity between the immediate value of wheat and barley and the difficulties posed by teosinte may have been an important factor in the difference in the development of human societies in the New World and in Eurasia. A third favorable feature of the Fertile Crescent flora: Monoecious plants have a high proportion of self-pollinating plants—that is, they are usually self-pollinating but occasionally cross-pollinating.Recall that most wild plants are either monoecious plants that cross-pollinate regularly, or male and female individuals that necessarily depend on another individual for pollination.These facts of reproductive biology puzzled early farmers who had just found a high-yielding plant produced by a mutation whose offspring might lose their genetic advantage by interbreeding with other plants.Therefore, most crops come from a small number of wild plants.These wild plants are either monoecious, usually self-pollinating, or reproduce themselves vegetatively (for example, by genetically duplicating the roots of the parent plant).In this way, the abundance of monoecious self-pollinating plants in the Fertile Crescent flora helped early farmers, because it meant that the vast wild flora had a reproductive biology that was convenient for humans. Self-pollinating plants also came in handy for early farmers, since these plants occasionally cross-pollinated, creating new plant varieties to choose from.This occasional cross-pollination occurs not only between some individuals of the same species, but also between related species to produce interspecific hybrids.One such hybrid among the Fertile Crescent self-pollinating plants, bread wheat, has become the most valuable crop in the modern world. The first eight important crops domesticated in the Fertile Crescent were all self-pollinating plants.Three of these are self-pollinating cereal crops—einkorn wheat, emmer wheat, and barley—with the added advantage of wheat having a high protein content of 8% to 14%.By contrast, the most important cereal crops of East Asia and the New World—rice and maize, respectively—are low in protein, posing major nutritional problems. These were some of the advantages that the Fertile Crescent flora offered the earliest farmers: it included a surprisingly large number of wild plants amenable to domestication.However, the Mediterranean climate belt of the Fertile Crescent extends westward, passing through vast areas of southern Europe and northwestern Africa.There are four other areas in the world that resemble the Mediterranean climate zone: California, Chile, southwestern Australia, and South Africa (Figure 8.2).However, not only did these other Mediterranean climate zones fail to catch up with the Fertile Crescent as an early place for food production; they also did not produce indigenous agriculture at all.What kind of favorable conditions does this unique Mediterranean climate zone in the west of Eurasia have? It turns out that the Mediterranean climate zone, especially in the Fertile Crescent area, has five advantages over other Mediterranean climate zones.First, western Eurasia is clearly the largest area in the world belonging to the Mediterranean climate zone.As a result, there is a greater variety of wildlife there than in the smaller Mediterranean climate zones of southwestern Australia and Chile.Second, in the Mediterranean climate zone, the climate in the Mediterranean climate zone in the west of Eurasia has the greatest climate change, and the climate is different every season and every year.This climate change favored the evolution of annuals, which are particularly abundant in the flora.The combination of the abundance of species and the abundance of annuals means that the Mediterranean climate zone of western Eurasia is by far the region with the greatest variety of annuals. What this botanical wealth means for humans is illustrated by geographer Mark Bloomler's study of the distribution of wild grasses.Of the thousands of species of wild grasses in the world, Bloomler tabulated 56 of them with the largest seeds—nature’s cream of the crop: These grass seeds are at least 10 times heavier than medium grass seeds. times (see Table 8.1).Almost all of these plants are native to Mediterranean climate zones or other arid environments.In addition, they are all overwhelmingly concentrated in the Fertile Crescent and some other areas of the Mediterranean climate zone in western Eurasia, thus giving the original farmers a huge choice: the 56 most valuable wild grasses in the world Of the approximately 32 species of plants, in particular, barley and emmer wheat, the two earliest Fertile Crescent crops, rank third and thirteenth in seed size, respectively, of the 56 top crops.In contrast, Chile has only two Mediterranean climate zones, California and southern Africa each have one, and southwestern Australia has none.This fact alone goes a long way toward explaining the course of human history. A third advantage of the Fertile Crescent's Mediterranean climate is its wide variety of altitude and topography over short distances.Its heights range from the lowest point on earth (the Dead Sea) to the 18,000-foot mountains (near Tehran), thereby guaranteeing a corresponding change in the environment and, therefore, a wide variety of wild plants that could be the ancestors of crops .These mountains are surrounded by gentle lowlands criss-crossed by rivers, floodplains, and deserts suitable for irrigated agriculture.In contrast, the Mediterranean-type climate zone of southwestern Australia and, to a lesser extent, South Africa and western Europe shows less variation in either altitude, habitat, or topography. The height variation of the Fertile Crescent means that harvest seasons can be staggered: Highland plants go to seed somewhat later than lowland plants.Thus, hunter-gatherers could step up the hillside to harvest grain seeds as they matured, rather than being overwhelmed by concentrated harvest seasons at one altitude, where all grains ripen at the same time.Once crop cultivation began, it was easy for the first farmers to gather the seeds of wild grains and plant them on the moist valley floors.These wild grains, which grow on hillsides and depend on rainwater that never comes, can be grown reliably and less dependent on rainwater when they are planted on the bottom of damp valleys. The Fertile Crescent's biodiversity over small distances helped create a fourth advantage—the abundance of wild ancestors not only of important crops, but also of large domesticated mammals.As we shall see, there were few or no wild mammals suitable for domestication in other Mediterranean climate zones, such as California, Chile, southwestern Australia, and South Africa.In contrast, four large mammal species—goats, sheep, pigs, and cattle—were domesticated in the Fertile Crescent very early, probably earlier than any other animal except dogs anywhere else in the world.These animals are still today four of the five most important domesticated mammals in the world (Chapter 9).But their wild ancestors were most common in somewhat similar parts of the Fertile Crescent, but it turned out that the four animals were domesticated in different places: sheep probably in the central regions, goats or in the eastern highlands (Zha, Iran). Gross Mountains), or in the southwest (), pigs in the north-central, and cattle in the west, including Anatolia.However, although the areas in which the wild ancestors of these four animals were abundant were so different, they lived in such close proximity that once domesticated they moved easily from one part of the Fertile Crescent to another, thus The whole area ended up being full of these 4 animals. Agriculture in the Fertile Crescent began with the early domestication of eight so-called "ancestor crops" (because these crops pioneered agriculture in the region, and possibly the world).The eight ancestor crops are emmer, einkorn and barley among cereals; lentils, peas, chickpeas and bitter greens among pulses; and flax, a fiber crop.Of the eight crops, only two, flax and barley, have wide wild distributions outside the Fertile Crescent and Anatolia.Two other founder crops have only very small wild distributions, chickpea, which is restricted to southeastern Turkey, and emmer wheat, which is restricted to the Fertile Crescent itself.Thus, agriculture in the Fertile Crescent could begin with the domestication of locally available wild plants without waiting for the introduction of crops derived from domesticated wild plants elsewhere.In contrast, two of the eight founder crops could not have been domesticated anywhere in the world except the Fertile Crescent because they had no wild range elsewhere. With access to suitable wild mammals and plants, the Fertile Crescent ancestors were able to quickly assemble an efficient and balanced biological mix for intensive food production.This combination includes 3 grains as the main source of carbohydrates, 4 types of legumes (containing 20% ​​to 25% protein) and 4 types of livestock as the main source of protein, supplemented by the rich protein of wheat; and as fiber and oil One source of flax (called linseed oil: linseed contains about 40% oil).Finally, thousands of years after the domestication of animals and the emergence of food production, these animals also began to be used to produce milk and shear wool, and to help humans plow and transport.Thus, these crops and livestock of the Fertile Crescent's earliest farmers began to meet basic human economic needs: carbohydrates, protein, fat, clothing, traction, and transportation. One final advantage of early food production in the Fertile Crescent: There may have been less competition from hunter-gatherer lifestyles than in some areas, including the western Mediterranean coast.There are few large rivers in Southwest Asia and only a short coastline, so there are few aquatic resources (such as rivers and offshore fish and shellfish).There, one of the mammals hunted for meat is the gazelle.Gazelles are originally herd animals, but due to overexploitation due to population growth, their numbers have been greatly reduced.Thus, the overall benefits of food production quickly outweighed the overall benefits of hunting and gathering.Sedentary villages based on grains predated food production and made farming and pastoralism accessible to hunter-gatherers.In the Fertile Crescent, the transition from hunter-gatherers to food production was relatively rapid: as late as 9000 BC, people had no crops and livestock and relied entirely on wild food, but by 6000 BC some societies had Almost completely dependent on crops and livestock. The situation in Mesoamerica is in sharp contrast to this: there are only two domesticable animals in that area (the turkey and the dog), which provide far less meat than cattle, sheep, goats, and pigs; and I have explained However, maize, the staple grain of Mesoamerica, was difficult to domesticate and perhaps slow to develop.Thus domestication of plants and animals in Mesoamerica probably did not begin until around 3000 BC (this date is still very uncertain); It was not announced until about a year ago. In all this discussion of the many advantages that contributed to the early emergence of food production in the Fertile Crescent, I have not been able to bring up any imagined advantages of the Fertile Crescent peoples themselves.In fact, I don't know if anyone has seriously suggested that the populations of that region had any supposedly distinctive biological traits that would have helped to realize the great power of food production in that region.Instead, I see that the Fertile Crescent's climate, environment, and many distinctive features of its wildlife provide a convincing explanation.Since the forces of overall food production that developed locally in New Guinea and the eastern United States were much smaller, perhaps the explanation has to do with ethnic groups in those areas?Before we turn to those regions, however, we must consider two related issues.In any region of the world, as long as there is no independent development of food production, or the final strength of the entire food production is not so great, these two problems will arise.The first question is: did hunter-gatherers and the first farmers really know much about the variety of wild species that existed in the area and their uses, or might they have overlooked the potential ancestors of some staple crops?The second question is: If they did know the local flora and fauna, did they use that knowledge to domesticate the most useful species in existence, or was there some cultural factor that prevented them from doing that? Regarding the first question, there is a discipline called ethnobiology that studies how well people know the plants and animals in their environment.This discipline is primarily concerned with the world's few surviving hunter-gatherer groups and agricultural tribes that still rely heavily on wild foods and natural products.These studies generally show that these groups are living encyclopedias of natural history, they name (in the local language) as many as 1,000 or more species of plants and animals, and their knowledge of the biology, geographical distribution and Potential uses have exhaustive knowledge.As people became increasingly reliant on domesticated plants and animals, this traditional knowledge gradually lost value and was lost, until people became modern supermarket shoppers who couldn't tell weeds from wild beans. Here is a typical example.For the past 33 years, I have conducted biological surveys in New Guinea and spent my time in the field, always accompanied by a group of New Guineans who still make extensive use of wildlife.One day, my friends from the Forey tribe and I were starving in the jungle because another tribe blocked our way back to the supply base.At this time, a man from the Forey tribe returned to the camp with a large rucksack full of mushrooms he had found.He starts to roast the mushrooms.I can finally have a big meal!But that's when I had a disturbing thought: What if these mushrooms were poisonous? I patiently explained to my Forey tribe friends that I had read in books that some mushrooms were poisonous, and that I had heard that even some mushroom collectors in the U.S. Experts also died from poisoning, and although we were all hungry, it was not worth the risk.At this point, my friends got angry and told me to shut up and listen to them.After years of asking them the names of hundreds of trees and birds, how can I insult them by thinking they don't even know the different mushrooms?Only Americans are stupid enough to not tell the difference between poisonous mushrooms and non-poisonous mushrooms.They then gave me a lesson in 29 types of edible mushrooms, the Fore name for each, and where to find it in the forest.This type of mushroom is called Tanti, it grows on trees, and it is delicious and absolutely edible. Every time I take the New Guineans to other parts of the island, they always talk about the local flora and fauna with other New Guineans they meet, and collect plants that may be useful and bring them back to their villages Try planting.My experiences with New Guineans are comparable to those of ethnobiologists who study traditional groups elsewhere.Yet all of these groups were either engaged in at least some kind of food production or were the last remnants of the world's partially assimilated past hunter-gatherer societies.Knowledge of wild species was presumably much richer before food production, when everyone on the planet was still entirely dependent on eating wild species.The earliest farmers inherited this knowledge, accumulated over tens of thousands of years of observation of nature by biologically modern humans living in close dependence on nature.It therefore seems highly unlikely that a potentially valuable wild species would have escaped the attention of the earliest farmers. A related question is whether ancient hunter-gatherers and farmers alike made good use of their ethnobiological knowledge in selecting wild plants for gathering and eventual cultivation.An example that can be used for verification comes from an archaeological site called Tell Abu Hureyra on the edge of the Euphrates Valley in Syria.The people who lived there may have been settled in villages year-round from 10,000 BC to 9,000 BC, but they were still hunter-gatherers; crop cultivation only began in the next 1,000 years.Archaeologists Gordon Hillman, Susan Colic and David Harris recovered from the site a large number of charred plant remains that may have been brought back by the site's inhabitants after being collected elsewhere. Abandoned piles of useless wild plants.The scientists analyzed more than 700 samples, each containing an average of more than 500 identifiable seeds belonging to more than 70 species of plants.It turned out that the villagers collected a huge variety (157!) of plants that were identified from the charred seeds, not to mention others that could not be identified at this time. Did these ignorant villagers gather every seed plant they found, take it home, and get poisoned by eating most of it, while subsisting on only a few?No, they wouldn't be that stupid.While these 157 plant species sound like the result of indiscriminate collection, there are many more plants that grew in the nearby wilderness that were not found among the charred remains.The 157 selected plants were divided into 3 categories.Among these are many plants whose seeds are not poisonous and are therefore immediately edible.Some other plants, such as beans and mustards, have poisonous seeds, but the poison is easily removed and the seeds are still edible.Some seeds belong to plants traditionally used as sources of dyes and medicines.Many of the wild plants not included in the 157 selected species may be of little use or may be harmful to humans, including some of the most poisonous weeds that grow locally. Thus, the hunter-gatherers of Tell Abramella did not waste their time indiscriminately collecting wild plants that might endanger their own lives.相反，他们同现代的新几内亚人一样，显然对当地的野生植物有深刻的了解，所以他们就利用这种知识只去选择现有的最有用的种子植物并把它们带回家。但是，这些被收集来的种子竞构成了促使植物驯化迈出无意识的第一步的材料。 关于古代族群如何明显地充分利用他们的人种生物学知识这个问题，我的另一个例子来自公元前9000年的约旦河谷，最早的作物栽培就是在这一时期在那里开始的。约旦河谷最早驯化的谷物是大麦和二粒小麦，它们在今天仍是世界上最高产的作物。但和在特勒阿布胡瑞拉一样，另外数百种结籽的野生植物必定就生长在这附近，其中l00种或更多可能是可以食用的，因此在植物驯化出现前就已被人采集。对于大麦和二粒小麦，是什么使它们成为最早的作物'约旦河谷的那些最早的农民难道对植物学一窍不通，竟然不知道自己在于什么？或者，难道大麦和二粒小麦竟是他们所能选择的当地最好的野生谷物？ 有两个以色列科学家奥弗·巴尔—约瑟夫和莫迪凯·基斯列夫通过研究今天仍在约旦河谷生长的野生禾本科植物来着手解决这个问题。他们舍弃了那些种子小或种子不好吃的品种，挑选出23种种子最好吃的也是最大的野生禾本科植物。大麦和二粒小麦在被选之列，这是毫不奇怪的。 但如认为其他21种候补的禾本科植物可能同样有用，那是不正确的。在那23种禾本科植物中，大麦和二粒小麦从许多标准看都是最好的。二粒小麦的种子最大，大麦的种子次大。在野生状态中，大麦是23种中产量最高的4种之一，二粒小麦的产量属于中等。大麦还有一个优点：它的遗传性和形态使它能够迅速形成我们在前一章所讨论的种子传播和发芽抑制方面的变化。然而，二粒小麦也有补偿性的优点：它比大麦容易采集，而且它还有一个不同于其他谷物的独特之处，因为它的种子容易和外壳分离。至于其他21种禾本科植物的缺点包括：种子较小，在许多情况下产量较低，在有些情况下它们是多年生植物，而不是一年生植物，结果它们在驯化过程中的演化反而会变得很慢。 因此，约旦河谷最早的农民从他们能够得到的23种最好的野生禾本科植物中选择了这两种最好的。当然，在栽培之后产生的演化，如种子传播和发芽抑制方面的改变，可能是这些最早的农民的所作所为的意想不到的结果。但是，他们在把谷物采集下来带回家去栽培时，一开始就选择了大麦和二粒小麦而不是其他谷物，这可能是有意识的行动，是以种子大小、好吃和产量高这些容易发现的标准为基础的。 约旦河谷的这个例子同特勒阿布胡瑞拉的例子一样，说明最早的农民为了自己的利益利用了他们对当地植物的丰富知识。除了少数几个现代的专业植物学家外，他们对当地植物的了解远远超过了其他所有的人，因此他们几乎不可能不去培育任何有用的比较适合驯化的野生植物。 同新月沃地的粮食生产相比，世界上有两个地方（新几内亚和美国东部）虽然也有本地的粮食生产系统，但显然是有缺陷的。现在我们可以来考察一下，当更多产的作物从别处引进这两个地方后，当地的农民究竟在做些什么。如果结果证明没有采纳这些作物是由于文化原因或其他原因，那么我们就会产生无法摆脱的怀疑。尽管我们迄今进行了各种各样的推理，我们可能仍然不得不怀疑，在当地的野生植物群中隐藏着一种潜在的重要作物的真正祖先，只是由于同样的文化因素，当地农民未能加以利用罢了。这两个例子同样会详细地说明一个对历史至关重要的事实：地球上不同地区的当地作物并不是同样多产的。 新几内亚是仅次于格陵兰的世界第二大岛，它在澳大利亚北面，靠近赤道。由于地处热带，加上十分多样化的地形和生境，新儿内亚的动植物品种非常丰富，虽然在这方面它因是一个海岛，比起大陆热带地区来有所不及。人类在新几内亚至少已个活了4万年之久——比在美洲长得多，比解剖学上的现代人类在欧洲西部生活的时间也稍长一些。因此，新几内亚人有充分的机会去了解当地的植物群和动物群。他们是否积极地把这种知识用来发展粮食生产呢？ 我已经提到，采纳粮食生产涉及粮食生产的生活方式与狩猎采集的生活方式之间的竞争。在新几内亚，狩猎采集的回报还没有丰厚到可以打消发展粮食生产的积极性。尤其是，现代新几内亚的猎人由于野生猎物的不足而处于受到严重损害的不利地位：除了100磅重的不会飞的乌（鹤鸵）和50磅重的袋鼠外，没有更大的本土陆地动物。沿海低地的新几内亚人的确获得了大量的鱼和有壳水生动物，而内地的有些低地人今天仍然过着狩猎采集生活，尤其要靠西谷椰子维持生存。但在新几内亚高原地区，没有任何居民仍然过着狩猎采集生活；相反，所有现代高原居民都是农民，他们只是为了补充日常饮食才利用野生食物。当高原居民进入森林去打猎时，他们带去路上吃的是园子里种的蔬菜。如果他们不幸断了粮，他们甚至会饿死，尽管他们熟知当地可以得到野生食物。既然狩猎采集的生活方式在现代新几内亚的很大一部分地区是这样地行不通，那么今天新几内亚所有的高原居民和大多数低地居民成了具有复杂的粮食生产系统的定居农民，这就没有什么奇怪的了。广阔的、昔日覆盖着森林的高原地区，被传统的新几内亚农民改造成围上了篱笆、修建起排水系统、精耕细作的、能够养活稠密人口的农田系统。 考古学的证据表明，新几内亚农业起源很早，约公元前7000年。在这早期年代里，新几内亚周围的所有陆块仍然只有狩猎采集族群居住，因此这一古老的农业必定是在新几内亚独立发展起来的。虽然从这些早期农田里还没有发现明确的作物残骸，但其中可能包含了欧洲人殖民时期在新几内亚种植的那几种作物，而且现在已经知道，这些作物都是从它们的新儿内亚野生祖先在当地驯化出来的。在本地驯化的这些植物中位居最前列的是现代世界的主要作物甘蔗。今天甘蔗年产量的总吨数几乎等于第二号作物和第三号作物（小麦和玉米）产量的总和。其他一些肯定原产新几内亚的作物是香蕉、坚果树、巨大的沼泽芋以及各种各样可吃的草茎、根和绿叶蔬菜。面包果树和根用作物薯蓣及（普通）芋艿可能也是在新儿内亚驯化的，虽然这种结论仍然不能确定，因为它们的野生祖先并不限于新几内亚，而是从新几内亚到西南亚都有分布。至于它们究竟像传统所认为的那样是在西南亚驯化的，还是在新几内亚或甚至只是在新几内亚独立驯化的，目前我们还缺乏能够解决这个问题的证据。 然而，结果证明，新几内亚的生物区系受到3个方面的严重限制。首先，在新几内亚没有任何驯化的谷类作物，而在新月沃地、萨赫勒地带和中国都有几种极其重要的谷类作物。新几内亚重视根用作物和树生作物，但它却把我们在其他湿润的热带地区（亚马孙河流域、热带西非和东南亚）的农业体系中所看到的一种倾向推向极端，因为那些地区的农民虽也重视根用作物，但却设法培育了至少两种谷物（亚洲稻米和一种叫做薏苡的大籽粒亚洲谷物）。新几内亚未能出现谷物农业的一个可能的原因，是那里的野生起始物种具有一种引人注目的缺点：世界上56种种子最大的野生禾本科植物没有一种是生长在那里的。 其次，新几内亚的动物群中没有任何可以驯化的大型哺乳动物。现代新几内亚驯养的动物只有猪、鸡和狗，它们也都是在过去几干年中经由印度尼西亚从东南亚引进的。因此，虽然新几内亚的低地居民从他们捕捉到的鱼类获得了蛋白质，但新几内亚的高原地区的居民在获得蛋白质方面受到严重的限制，因为给他们提供大部分卡路里的主要作物（芋艿和甘薯）的蛋白质含量很低。例如，芋艿的蛋白质含量几乎不到1％，甚至比白米差得多，更远在新月沃地的小麦和豆类（蛋白质含量分别为8％一14％和20％—25％）之下。 新几内亚高原地区的儿童患有膨胀病，这是饮食量多但蛋白质缺乏所引起的典型的疾病。新几内亚人无分老幼，常常吃老鼠、蜘蛛、青蛙和其他小动物，而在别的地方，由于能够得到大型家畜或大型野生猎物，人们对那些东西是不屑一顾的。蛋白质缺乏可能也是新儿内亚高原社会流行吃人肉的根本原因。 最后，以往新几内亚能够得到的根用作物不但蛋白质少，而且卡路里也不高，因为这些作物在如今生活着许多新几内亚人的高地上生长不好。然而，许多世纪前，一种原产于南美洲的新的根用作物传到了新几内亚，它先由西班牙人引进菲律宾，后来大概再由非律宾传到新几内亚的。同芋艿和其他可能历史更悠久的根用作物相比，甘薯能够在地势更高的地方生长，长得更快，按每英亩耕地和每小时所花的劳力计算，产量也更高。甘薯引进的结果是高原人口激增。就是说，虽然在甘薯引进前人们在新几内亚高原地区从事农业已有数千年之久，但当地现有的作物一直在他们能够居住的高原地区使他们能够达到的人口密度受到了限制。 总之，新几内亚提供了一个和新月沃地截然不同的富于启发性的对比。同新月沃地的狩猎采集族群一样，新几内亚的狩猎采集族群也是独立地逐步形成粮食生产的。然而，由于当地没有可以驯化的谷物、豆类植物和动物，由于因此而带来的高原地区蛋白质的缺乏，同时也由于高原地区当地现有根用作物的局限，他们的土生土长的粮食生产受到了限制。不过，新几内亚人对他们现有的野生动植物的了解，一点也不比今天地球上的任何民族差。他们同样能够发现并检验任何值得驯化的野生植物。他们完全能够认出在他们现有的作物之外的其他一些有用的作物，他们在甘薯引进时兴高采烈地接受了它就是证明。今天，这个教训在新几内亚正在又一次被人们所接受，因为那些具有优先获得引进的新作物和新牲畜的机会（或具有采纳它们的文化意愿）的部落发展壮大了自己，而受到损害的则是那些没有这种机会或意愿的部落。因此，新几内亚土生土长的粮食生产所受到的限制与新几内亚的族群没有任何关系，而是与新几内亚的生物区系和环境有着最密切的关系。 的另一个例子来自美国东部。同新几内亚一样，那个地区也为独立驯化当地的野生植物提供了条件。然而，人们对美国东部早期发展的了解，要比对新几内亚早期发展的了解多得多：美国东部最早的农民所种植的作物已经得到确认，当地植物驯化的年代和作物序列也已为人们所知。在其他作物开始从别处引进之前很久，美洲土著便已在美国东部的河谷地区定居下来，并在当地作物的基础上发展了集约型的粮食生产。因此，他们有能力去利用那些最有希望的野生植物。他们实际上栽培了哪些野生植物，以及怎样把由此而产生的当地一系列作物去和新月沃地的一系列始祖作物作一比较呢？ 原来美国东部的始祖作物是4种植物，它们在公元前2500年至l500年这一时期得到驯化，比新月沃地的小麦和大麦的驯化时间晚了整整6000年。当地的一种南瓜属植物不但能产生可吃的种子，而且还可用作小型容器。其余3种始祖作物完全是因为它们的可吃的种子才被人栽种的（向日葵、一种叫做菊草的雏菊亲缘植物和一种叫做藜的菠菜远亲植物）。 但4种种子作物和一种容器远远够不上完全的粮食生产组合。这些始祖作物在2万年中不过是饮食的小小补充，美国东部的印第安人仍然主要地依赖野生食物，尤其是野生的哺乳动物和水鸟、鱼、有壳水生动物和坚果。直到公元前500年至200年这一时期，在又有3种种子作物（扁蓄、五月草和小大麦）得到栽培之后，农业才成为他们食品的主要部分的来源。 现代的营养学家可能会对美国东部的这7种作物大加赞赏。它们的蛋白质含量都很高——达17％一33％，而小麦是8％一14％，玉米是9％，大麦和白米甚至更低。其中两种——向日葵和菊草含油量也很高（45％一47％）。尤其是菊草，由于含有32％的蛋白质和45％的油，可能成为营养学家梦寐以求的最佳作物。我们今天为什么仍然没有吃上这些理想的粮食呢？ 唉，美国东部的这些作物的大多数虽然在营养方面有其优点，但它们在其他方面也存在严重的缺点。藜属植物、扁蓄、小大麦和五月草的种子很小，体积只有小麦和大麦种子的十分之一。更糟的是，菊草是靠风媒传粉的豚草的亲缘植物，而豚草是众所周知的引起花粉病的植物。同豚草的花粉一样，凡是在菊草长得茂盛的地方，菊草的花粉都会引起花粉病。如果这一点还不能使你想要做一个种植菊草的农民的热情完全稍失的话，就请你注意它有一种今某些人讨厌的强烈气味，而且接触到它会引起皮肤过敏。 公元元年后，墨西哥的一些作物最后经由贸易路线开始到达美国东部。玉米是在公元200年左右引进的，但在许多世纪中，它所起的作用始终较小。最后，在公元900年左右，一个适应北美洲短暂夏季的新品种的玉米出现了，而在公元1100年左右随着豆类的引进，墨西哥的玉米、豆类和南瓜类这三位一体的作物便齐全了。美国东部的农业大大地集约化了，人口稠密的酋长管辖的部落沿密西西比河及其支流发展了起来。在某些地区，原来在当地驯化的作物同远为多产的墨西哥三位一体的作物一起保留了下来，但在另一些地区，这三位一体的作物则完全取代了它们。没有一个欧洲人见到过生长在印第安人园子里的菊草，因为到欧洲人于公元1492年开始在美洲殖民时，菊草作为一种作物已经消失了。在美国东部所有这些古代特有作物中，只有2种（向日葵和东部南瓜）能够同在其他地方驯化的作物相媲美，并且至今仍在种植。我们现代的橡实形南瓜和密生西葫芦就是从几千年前驯化的美洲南瓜属植物演化而来的。 因此，像新几内亚的情形—样，美国东部的情形也是富于启发性的。从假定出发，这个地区看来可能具有促进当地多产农业的条件。它有肥沃的土壤，可靠而适中的雨量，以及保持今天丰产农业的合适的气候。该地的植物群品种繁多，包括多产的野生坚果树（橡树和山核桃树）。当地的印第安人发展了以当地驯化植物为基础的农业，从而在村庄里过着自给自足的定居生活，他们甚至在公元前200年至公元400年期间带来了文化的繁荣（以今天俄亥俄州为中心的霍普韦尔文化）。这样，他们在几千年中就能够把最有用的可以得到的任何野生植物当作潜在的作物来加以利用。 尽管如此，霍普韦尔文化繁荣的出现，还是比新月沃地乡村生活的出现晚了差不多9000年。不过，直到公元900年之后，墨西哥三位一体的作物组合才引发了人口的较大增长，即所谓的密西西比文化的繁荣。人口的增长使墨西哥以北的印第安人得以建设最大的城镇和最复杂的社会。但这种人口的增长毕竟来得太晚，没有能使美国的印第安人为迫在眉睫的欧洲人殖民灾难作好准备。仅仅以美国东部的作物为基础的粮食生产，还不足以引发人口的增长，这原因是不难说明的。这一地区现有的野生谷物，远远不如小麦和大麦那样有用。美国东部的印第安人没有驯化过任何可在当地得到的豆类、纤维作物、水果树或坚果树。除了狗，他们没有任何家畜，而狗大概也是在美洲的其他地方驯化的。 有一点也是很清楚的：美国东部的印第安人对他们周围的野生植物中潜在的主要作物并未视而不见。即使是用现代科学知识武装起来的20世纪植物育种专家，在利用北美的野生植物方面也很少取得成功。诚然，我们现在已把美洲山核桃驯化成一种坚果树并把乌饭树的蓝色浆果驯化成一种水果，而且我们也已把欧亚大陆的一些水果作物（苹果、李、葡萄、树莓、黑刺莓、草莓）同北美的野生亲缘植物进行杂交来改良品种。然而，这几项成就对我们饮食习惯的改变，远远不及公元900年后墨西哥的玉米对美国东部印第安人饮食习惯的改变那样深刻。 对美国东部驯化植物最了解的农民，就是这个地区的印第安人自己。他们在墨西哥三位一体的作物引进后宣判了当地驯化植物的命运：或者把它们完全抛弃，或者把它们的重要性降低。这个结果也表明了印第安人没有受到文化保守主义的束缚，而是在看到一种优良的植物时完全能够认识到它的价值。因此，同在新几内亚一样，美国东部土生土长的粮食生产所受到的限制，不是由于印第安人本身，而是完全决定于美洲的生物区系和环境。 现在，我们已经考虑了3个对照地区的例子，在这3个例子中，粮食生产都是土生土长的。新月沃地处于一个极端；新几内亚和美国东部处于另一个极端。新月沃地的族群对当地植物的驯化在时间上要早得多。他们驯化了多得多的植物品种，驯化了产量多得多或价值大得多的植物品种，驯化了范围广泛得多的各种类型的作物，更快地发展了集约型粮食生产和稠密的人口，因此，他们是带着更先进的技术、更复杂的行政组织和用以传染其他族群的更流行的疾病进人现代世界的。 我们发现，新月沃地、新几内亚和美国东部的这些差异，直接来自可以用来驯化的野生动植物的不同系列，而不是来自这些族群本身的局限性。当更多产的作物从别处引进时（新几内亚的甘薯，美国东部的墨西哥三位一体的作物），当地族群迅即利用了它们，加强了粮食生产，从而大大地增加了人口。如果把范围加以扩大，依我看在地球上的—些根本没有在当地发展出粮食生产的地区——加利福尼亚、澳大利亚、阿根廷无树大草原、欧洲西部等等——适合驯化的野动植物可能比新几内亚和美国东部还要少，因为在新几内亚和美国东部至少还出现了有限的粮食生产。事实上，无论是本章中提到的马克·布卢姆勒在世界范围内对当地现有的大籽粒野生禾本科植物的调查，还是下一章中将要述及的在世界范围内对当地现有的大型哺乳动物的调查，都一致表明，所有这些不存在本地粮食生产或只有有限的本地粮食生产的地区，都缺少可驯化的牲畜和谷物的野生祖先。 请回忆一下：粮食生产的出现涉及粮食生产与狩猎采集之间的竞争问题。因此，人们也许想要知道，粮食生产出现缓慢或没有出现粮食生产这种种情况，可能是由于当地可以猎取和采集的资源特别丰富，而不是由于适合驯化的物种特别容易获得。事实上，当地粮食生产出现很晚或根本没有出现粮食生产的大多数地区，向狩猎采集族群所提供的资源持别贫乏而不是特别丰富，因为澳大利亚和美洲（而不是欧亚太陆和非洲）的大多数大型哺乳动物，到冰期快结束时已经灭绝。粮食生产所面临的来自狩猎采集的竞争，在这些地区甚至比在新月沃地少。因此，在当地未能出现粮食生产或粮食生产受到限制这些情况，决不能归咎于来自大量狩猎机会的竞争。 为了不使这些结论被人误解，我们在结束这一章时应该提出不可夸大两个问题的告诫：一些族群接受更好的作物和牲畜的意愿，和当地现有的野生动植物所带来的限制。这种意愿和限制都不是绝对的。 我们已经讨论厂许多关于当地族群采纳在别处驯化的更多产的作物的例子。我们的一般结论是：人们能够认识有用的植物，因此大概也会认识当地适合驯化的更好的植物，如果这种植物存在的话，而且他们也不会由于文化保守主义和禁忌而不去那样做。但是，必须对这句话加上一个重要的限定语：“从长远观点看和在广大地区内”。任何一个了解人类社会的人都能举出无数的例子，来说明一些社会拒绝接受可能会带来利益的作物、牲畜和其他新事物。 当然，我并不赞成那种明显的谬论，即认为每一个社会都会迅速地采纳每一个可能对它有益的新事。事实上，在整个大陆和其他—些包含数以百计的互相竞争的广大地区，有些社会对新事物可能比较开放，有些社会对新事物可能比较抵制。那些接受新作物、新牲畜或新技术的社会因而可能吃得更好，繁殖得更快，从而取代、征服或杀光那些抵制新事物的社会。这是一个重要的现象，它的表现远远超过了采纳新作物的范围，我们将在第十三章再回头讨论这个问题。 我们的另一个告诫涉及当地现有的野生物种使粮食生产的出现所受到的限制。我不是说，在所有那些在现代以前实际上不曾在当地出现粮食生产的地区，不管经过多少时间也不可能出现粮食生产。今天的欧洲人因为看到澳大利亚土著进人现代世界时的身份是石器时代的狩猎采集族群，使常常想当然地认为这些土著将永远如此。 为了正确认识这种谬误，请考虑一下有一个天外来客在公元前3000年）年访问地球。这个外星人在美国东部可能没有看到粮食生产，因为直到公元前2500年左右粮食生产才在那里开始出现。如果这个公元前3000年的外星人得出结论说，美国东部野生动植物所造成的限制永远排除了那里的粮食生产，那么在随后1000年中发生的事情可能证明这个外星人错了。甚至是在公元前9000年而不是8500年来到新月沃地的游客，也可能会误以为新月沃地永远不适合粮食生产。 换言之，我的论点不是说加利福尼亚、澳大利亚、欧洲西部以及没有本地粮食生产的所有其他地区没有可驯化的物种，而且如果不是外来的驯化动植物或族群的到来，那些地方可能仍然为狩猎采集族群无限期地占有。相反，我注意到地区之间在现有的可驯化物种的储备方面差异甚大，这些地区的本地粮食生产出现的年代也相应地有所不同，而且在某些肥沃地区直到现代仍没有独立出现过粮食生产。 澳大利亚这个据称最“落后的”大陆很好地说明了这个问题。澳大利亚东南部是这个大陆上水源充足、最适合粮食生产的地方。那里的土著社会在最近的几千年里似乎一直在按照一种可能最终导致本地粮食生产的发展轨迹在演化。他们已经建立了过冬的村庄。他们已经开始加强利用它们的环境，建造渔栅、编织渔网，甚至挖掘长长的水渠来从事渔业生产。如果欧洲人没有在1788年向澳大利亚殖民，从而中途破坏了那个独立的发展轨迹，那么澳大利亚土著也许不消几千年就可成为粮食生产者，照料一池池驯化了的鱼，种植驯化了的澳大利亚薯蓣和小籽粒的禾本科植物。 根据这一点，我现在就能够回答包含在本章标题里的那个问题。我提出的那个问题是：北美印策安人未能驯化北美苹果的原因是在印第安人还是在苹果。 我并非因此就暗示说苹果不可能在北美驯化。请记住：苹果在历史上是最难栽培的果树之一，也是在欧亚大陆驯化的最后一批主要的果树之一，因为苹果的繁殖需要复杂的嫁接技术。直到希腊古典时期，即欧亚大陆粮食生产开始出现后8000年，即使在新月沃地和欧洲也没有关于大规模驯化苹果的证据。如果美洲印I第安人开始以同样的速度发明或学会嫁接技术，并终于也驯化了苹果，那也要在公元5500年左右，即北美在公元前2500年左右出现植物驯化后大约8000年。 因此，在欧洲人到达时印第安人仍未能驯化北美的苹果，其原因不在印第安人，也不在苹果。就苹果驯化必要的生物条件而言，北美印第安农民和欧亚大陆农民一样，北美的野生苹果也和欧亚大陆的野生苹果一样。事实上，本章读者现在正在津津有味地吃着的从超市上买来的苹果，有些品种就是不久前将欧亚大陆的苹果同北美的野生苹果进行杂交而培育出来的。印第安人未能驯化苹果的原因却是在于印第安人所能得到的整个野生动植物组合。这个组合的不太多的驯化潜力，就是北美粮食生产很晚才开始的主要原因。

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