As we presented in module one, agriculture is currently the predominant environment-food system, including the production of both crops and livestock for human consumption. But it was not always this way and other environment-food systems continue to exist, as exemplified by the world's wild-caught ocean fisheries. Module 2.1 first examines the human-natural systems of hunter-gatherers, and then the human-natural systems of early agriculture. The domestication of plants and animals, together with the origins of agriculture, resulted in some of the most profound transformations of environments and human societies, and are a key part of the Anthropocene or "human recent past" presented in the first module. Module 2.2 then describes more recent environment-food systems and those of today.
Hunting and gathering activities were the primary way for humans to feed themselves from their natural environments for over 90% of human history. Gathering plant products, such as seeds, nuts, and leaves, is considered to have been the primary activity in these early human-natural food systems, with hunting mostly secondary. The mix of hunting-gathering activities and the tools used varied according to the environment. Among many hunter-gatherer groups worldwide fire was one of the most important tools and was used widely. Fire was used by these human social systems to transform natural systems in habitats ranging from grasslands and open forests, such as those of Africa, Asia, Europe, and North America, to those of denser forests that included the Amazon rain forest of South America. One importance of fire was that it helped enable hunter-gatherers to “domesticate the landscape” so that it yielded more of the desired plants through gathering and the sought-after animals through hunting.
Fire also was and is crucial in enabling humans to cook food. Cooking rendered animals and many plants into forms that humans were significantly more able to digest. The capacity to cook foods through the use of fire----which was obtained through gathering and hunting---may have arisen as long ago as 1.8 – 1.9 million years ago at about the same general time as the emergence of our ancestral species Homo erectus on the continent of Africa. (Homo erectus subsequently evolved to Homo sapiens, our own species, about 200,000 years ago). These early humans were able to extract significantly more energy from food as a result of cooking. In short, cooking enabled through the use of fire, produced chemical compounds in food that were more digestible and energy-dense. While the changes and challenges of human diets and nutrition continued to evolve---they are a focus of Module 3 —this early shift to cooking through the use of fire was one of the most influential in our history.
Hunter-gatherer peoples are assumed to have used thousands of different types of plant species and, at the least, hundreds of different animal species. In many cases, the impact on the environment or natural systems was only slight or moderate, since population densities were low and their use of the environment was dispersed. Populations were relatively small and technology was fairly rudimentary. In a few cases, environmental impacts were significant, such as the use of fire as discussed above. Hunting pressure also could have led to significant environmental impacts. It is hypothesized that hunting by groups in North America contributed to the extinction of approximately two-thirds of large mammal species at the end of the last Ice Age around 10,000-12,000 years ago. The human role in this extinction episode, referred to as the Pleistocene Overkill Hypothesis, was combined with the effects of other changes. Climate and vegetation changes in particular also impacted the populations of these large mammals and made them more vulnerable to hunting pressure.
We know less about the societies and social structure (human systems) of these groups. However, work with recent and present-day hunter-gatherers suggests they had high levels of egalitarianism since livelihood responsibilities are widely shared and not easily controlled by single individuals or small groups within these groups. One thing we do now know is that hunter-gatherers have been related to agricultural peoples in a number of ways. A first and obvious way is that in the history of human groups and food systems, "we" were all hunter-gatherers once, and across a wide range of environments agriculturalists emerged from hunting and gathering in their origin. Another is that hunter-gatherers sometimes coexist with agriculturalists and may even have conducted rudimentary trade. Last, there are even cases of hunting and gathering emerging from agricultural groups. In Africa and South America, for example, the Bantu or Bushmen (in southern Africa) and the Gi (in present-day Brazil) are thought to have been agriculturalists prior to assuming hunter-gatherer lifestyles. These changes presumably owed to lessening population densities and the opportunity for more feasible livelihoods through hunting and gathering given the circumstances these peoples faced. This re-emergence of hunting and gathering is an excellent example of the sort of human natural-coupling we consider in this module and apply to the history of food systems: the social factor of lessening population densities, and perhaps something the re-emergence of more wild ecosystems in natural landscapes, allowed these agriculturalists to re-adopt hunting and gathering, with consequent changes in the natural systems.
The origins of agriculture as the predominant mode of food production were dependent on the domestication of plants and animals. Domestication refers to the evolution of plants and animals into types that humans cultivate or raise; conversely domesticated types can no longer exist in the wild. Domestication and the social and environmental transformation that accompanied them are closely related to the Anthropocene and represent one of the most pivotal experiences ever, both of earth’s environments and in our history and evolution as a species. Domestication has been and is widely studied by interdisciplinary environmental and agricultural fields as well as various disciplines such as archaeology, biology, geography, genetics, and agronomy.
A couple of common definitions of domestication will help to underscore the importance of this concept. In a 1995 book on The Emergence of Agriculture, the archaeologist Bruce Smith defines domestication as “the human creation of a new form of plant or animal---one that is definitely different from its wild relatives and extant wild relatives”. In 2002 in the scientific journal Nature the geographer, Jared Diamond writes that an animal or plant domesticate is “bred in captivity [or in a field] and thereby modified from its wild ancestors in ways making it more valuable to humans its reproduction and food supply [nutrients in the case of plant domesticates]” (page 700). In other words, plant and animal domesticates have lost most or all the capacity to reproduce long-term populations in the wild---thus making domesticated populations of plants or animals different than ones that have been simply tamed or brought into cultivation on a one-time basis as single organisms. Expanding beyond these definitions, you can read more about domestication at National Geographic: domestication [1].
A great deal is now known about the nature of domestication and its timing, in addition to the place of origin of many domesticated crops and animals (covered on the next page). Illustrating the multiple disciplines needed to understand the history of food systems, this information owes to evidence and analysis in archaeology; biology, ecology, and agronomy; geography; anthropology; and genetics. For one, the domesticates in general, and our most important domesticated crops and animals in particular---such as wheat, rice, corn (maize), barley, potatoes, sorghum, cattle, pigs, and sheep, are recognized to have evolved from wild plants and animals that were selected, gathered, and brought back to camp by hunter-gatherers. Second, while a broad spectrum of wild plant and animal foods were being gathered and hunted prior to domestication the origins of agriculture represented a bottleneck. The effect of this bottleneck was that the number of major domesticates that became available to humans numbered in the several dozens, but not the thousands. Third, well-established demonstration of the actual dates of domestication varied from 8,000 - 10,000 years ago in the Near East (the Fertile Crescent of present-day Iraq, Turkey, Iran, and Syria) and China to the broad window of 4,000-8,000 years ago in several of the other world regions discussed next.
Domestication of plants and animals has been framed by many experts in terms of a " domestication syndrome" which refers to a set of traits or "syndrome" that are common to domesticates. Syndrome traits are ones that should be easy to remember because these traits confer usefulness to humans. In plants, for example, wild relatives may have shattering seed pods, where a seed is dropped on the ground as it ripens, while domesticates generally keep their seed on the plant to give humans greater convenience in harvesting. There are also dramatic increases in seed and inflorescence size in many plant domesticates in relation to wild relatives (e.g.. Fig. 2.1.1), as well as decreases in bitter or toxic substances that make food crops generally more appealing and nutritious to humans (and sometimes to wild herbivores as well, which then become pests!). Plant domesticates are generally less sensitive to day length as a requirement for flowering and reproduction, which means they complete their life cycles and produce grain and other products in a more predictable way for humans, and tend to have greater vigor as seedlings than wild relatives, which also follows from their larger seeds. In animals, the greater docility of animal pets and livestock, and traits such as floppy ears and general juvenile-type behavior of domesticated dogs are oft-cited examples of domestication syndrome. See if you can identify examples of these traits in the website presentation of domestication cited in the text above.
Just as for the dates and historical processes that led to domestication, the sites of plant and animal domestication are known from a similar interdisciplinary mix of perspectives, from archaeology to genetics. The map in Figure 2.1.2 and Table 1 show current knowledge of seven important areas of early agriculture where the world’s major crops and animals were domesticated. The question of crop and livestock origins and movements presented in this module is still an active and interesting area of research and more remains to be discovered. Most important of these areas was the Fertile Crescent of the Tigris-Euphrates river system and surrounding uplands in Southwest Asia---present-day Turkey, Iran, Iraq, and Syria. This region was responsible for the domestication of several major crops (wheat, barley, oats) and almost all the major domesticated animals (cattle, sheep, goats, pigs) that are incorporated today into major food systems worldwide (for the definition of food system see module 1.2). Like other areas it also included domesticated plants in particular that were significant components of local food systems and diets---such as bitter vetch and chickpeas—that did not become major global staples. China, which we identify as a single geographic area, was responsible for the domestication of rice, soybeans, millet, and several other domesticates that included tree crops such as the peach. Pigs were domesticated independently in China, meaning the pig population there that evolved to domesticated forms was separate from that of the Fertile Crescent. It is likely that China contained two separate areas of major importance in our global overview: the Yangtze River basin and the Wei (Yellow) River valley.
Four other major world regions were also vitally important as sites of early agriculture and in the domestication of major crops and animals. Southeast Asia including New Guinea and the Pacific Islands is an expansive geographic area where staples such as various species of yam, citrus, bananas, and sugar cane were domesticated (see Table 1). A significant size region of sub-Saharan Africa was also quite important, contributing crops such as sorghum, coffee, and species of millet other than the ones domesticated in East Asia (see Table 1). Geographically this area of sub-Saharan Africa includes the savanna areas of West Africa as well as the highlands of Ethiopia and Kenya. Locally within this region, such domesticates as teff and fonio, a pair of grain crops, became highly regarded foodstuffs.
In South America, the combination of the Andes mountains and the Amazon basin was an important area of early agriculture and domestication that included potatoes, sweet potatoes, peanuts, and manioc (or cassava). The Andes and Amazon also included many locally important domesticates such as quinoa and acai (the fruit of the acai palm) that recently have gained popularity as elements of global food systems. The area of Mexico (extending to the U.S. Southwest and southern Arizona in particular) and Central America is also important. This area’s contributions included corn (also known as maize) and domesticated species of bean, chili pepper, and squash in addition to the turkey. Eastern North America was also an important area of early agriculture though most domesticates there did not become familiar items in major contemporary food systems. Sunflower did though become relatively important and some of the domesticated plants of the northern parts of North America, such as cranberry and so-called Indian rice, did become moderately important foods.
Geographic World Region | Early Domesticated Crops Included | Early Domesticated Animals Included |
---|---|---|
East Asia (and Central and South Asia) | Rice; Buckwheat; Millets; Soybean; Peach; Nectarine; Apple (Central Asia); Apricot (South Asia) | Pigs |
Southeast Asia and Pacific Islands | Taro; Yam; Arrowroot; Banana; Sugar Cane; Coconut; Breadfruit; Orange; Lemon; Lime; Jack Bean; Winged Bean | Pigs, Chicken |
Near East | Wheats; Barley; Rye; Oat; Pea; Chickpea; Lentil; Vetch; Cherry; Almond | Pigs, Sheep, Goats, Cattle |
Sub-Saharan Africa: the East African Highlands and Sahelian Savanna | Sorghum; Pearl and Finger Millet; Teff; Ensete; Coffee; Yam; Pigeon Pea; Cowpea; Fonio | Cattle |
South America, principally the Andes mountains and the lowlands of Pacific Coast and Amazonia | Potatoes; Quinoa; Peanut; Lima Bean; Manioc (Cassava); Pineapple; Sweet Potato | Llama, Alpaca, Guinea Pig |
Mexico and Central America, mountain ranges and adjoining foothills and lowlands | Maize, Mesoamerican Common Bean (Kidney Bean) and Chile Pepper; Squash | Turkey |
Eastern North America | Sunflower, Sumpweed, Marsh Elder, Goosefoot or Lamb’s Quarter |
At this juncture, it’s important to note some important points for understanding the environment-food interactions that arise from our discussion thus far of hunting-gathering, domestication, and early agriculture. This geographic and historical context highlights the importance of the independent establishment of early agriculture through domestication in multiple geographic areas across diverse world regions. Our description of current knowledge emphasizes the importance of seven world geographic areas, but other variants of this accounting are possible. Crop origin areas could potentially be more numerous, for example, if we counted additional distinct sub-areas of China, Sub-Saharan Africa, and South America. It is interesting that the major modern population centers, the Eastern United States and Northern Europe, seem to have been less important than other world regions in the domestication of the major staple grains and vegetables. As noted above, the question of crop origins and the relations of humans to crops via domestication, breeding, and knowledge of how to cultivate crops remains an active and fascinating area of research.
Our description also highlights the domestication of a handful of specific species of major crops (approximately 100 species) and major animal domesticates (14 species). These domesticated species are the same ones we still recognize today as the most valuable cornerstones of our current food systems as well as being central elements in their environmental impacts. When local crops and livestock are added the numbers of these domesticates is significantly higher (upwards of 500 species). Still, the number of species in this new agricultural biota paled in comparison to the thousands of species that have been the basis of human livelihoods in hunter-gatherer systems. In other words, early agriculture meant that humans narrowed their focus on a select group of species in the biotic world, namely the ones that were most productive and could be most feasibly and effectively produced and consumed. In doing so, humans intensified the level of interaction, knowledge, and cultural importance of these crop species as a fundamental human-natural relationship at the base of food systems from prehistory to the present day.
In a variety of subsequent units of this course, we will be considering the diversity of crops and animals in agriculture as we explore the agroecology and geosystems of food production (Section II) and the role of human-environment interactions amid such challenges as climate change, food security, human health, and environmental sustainability (Section III). In this module, we keep our focus on early agriculture and domestication. Our present focus will also require that we use the model of Coupled Natural-Human Systems (CNHS) through the remainder of Module 2.1 followed by continuation and expansion of this focus in the next module (Module 2.2) where we discuss a few of the major historical transformations leading to the world’s current situation with regard to the environment and food (Module 2.2).
The Coupled Natural-Human Systems, which we introduced in Module one, can be used as a framework to explain domestication events and early agriculture in the history of food systems. This framework is sometimes used to think about the "why" question of domestication, for example, "why did human and natural systems come together at a particular time in different parts of the world, including the middle east, so that plants were domesticated and agriculture started?; Why not earlier, and why not later?". The framework can also be used to explore the history of food systems after domestication, which is the subject of module 2.2.
You probably recall from module 1.2 that systems are assemblages of components and the relations between them. Two basic relations that can occur within systems, and that you likely included in your concept map of a food system example (summative evaluation 1.2) were those of a driver and a feedback relation. As you may already suspect, drivers are those processes or changes that can be said to impel or cause changes in other parts of a system, somewhat like a volume knob that causes the volume of music to increase in a room. In the example of the Pleistocene overkill hypothesis from module 2.1, for example, human hunting is thought of (hypothesized) as a dominant human system driver that eliminates the possibility of hunter-gatherers to easily find food, so that they may have been forced to develop early forms of agriculture. Excessive hunting is the driver, and collapsing prey animal populations, and eventually, domestication are responses. Meanwhile, feedback processes are those that can be said to be self-strengthening or self-damping (see module 1.2), and in the case of domestication, also may involve multi-driver processes where a response to a driver is another process that serves to strengthen both processes (positive feedback) or diminish the change (negative feedback). For example, as you will see in the next module, a common dynamic around the emergence of agriculture could be the coming together of excessive hunting, changing climate with worsening conditions for both wild game and crops, and the expansion of human settlements that may have also degraded the land. This combination of human and natural drivers could all tend to drive increased areas under cultivation to deal with the lack of food from hunting, and later the lack of food from soil degradation. A positive feedback emerges when the expansion of agriculture itself begins to change the climate, further eliminate prey, or reduce food availability from soil degradation. These processes would be thus said to interact as a positive feedback on domestication and the emergence and continuing expansion of agriculture. The diagram below (fig. 2.1.3) shows these potential drivers and feedback processes. the basic-level illustration shows the coupling of these two systems.
In Figure 2.1.3, then, the human factors that can change the environment we will refer to as “Human Drivers” or “Human Responses” of the CNHS model. The environmental factors that influence humans are referred to as “Environmental Drivers” or “Environmental Feedbacks.” As illustrated below with examples, the CNHS model describes the combined, interlocked changes of human behaviors and societies, on the one hand, and environmental systems including the plants and animals under domestication, on the other hand. This model is also referred to as a coevolutionary model since the drivers and feedbacks, including intentional and unintentional changes, influence subsequent states and the resulting development of the human-environment food system.
Before using these diagrams in Module 2.2 to explain the history of food systems (including the summative assessment which asks you to diagram some of these relationships yourselves), we'll illustrate the concept of drivers, feedbacks, and the coevolutionary emergence of food systems using a very specific diagram about the emergence of agriculture in Fig. 2.
The "story" of this diagram is as follows: First, climate change is one of the main environmental drivers that influenced early agriculture and domestication. At the end of the Pleistocene, the geologic epoch that ended with the last Ice Age, there was a worldwide shift toward warmer, drier, and less predictable climates relative to the preceding glacial period (Fig. 2.1.4, oval (1)). This climate shift that began in the Late Pleistocene resulted from entirely natural factors. Hunter-gatherer populations are documented to have been significantly influenced by this climate change. For example, many hunter-gatherer populations responded to this climate change by increasing the size and density of human populations near water sources such as river channels and oases (Figure 2.1.4, oval (2)). This climate change also led to the evolution of larger seed size within plants themselves (especially those plants known as annuals that grow each year from seed), which are summarized as part of the vegetation changes noted in Fig. 2.1.4. It may have also selected for annual plants being more apparent parts of natural environments in dry climates these humans inhabited, since surviving only one season as an annual plant, and setting seed that survives a dry period is one evolutionary response in plants to dry climates (see module 6 for the concept of annual and perennial life cycles). The driving factor of climate change thus led to responses in plants and human societies that are hypothesized to have acted as drivers for domestication and early agriculture. The driver of climate change is also thought to have concentrated the populations of the ancestors of domesticated animals. Their concentrated populations would have better-enabled humans to take the first steps toward animal domestication. Recognizing the importance of climate change we single it out as the main driver in Figure 2.1.4, though doubtless there were other interacting drivers.
Influential Human Drivers included such factors as population (demographic) pressure and socioeconomic demands for food and organization of food distribution were also highly important in contributing to the domestication of plants and animals and the rise of early agriculture (Figure 2.1.4, oval (2)). This pair of factors is also referred to as human to natural drivers, as shown in the diagram. The influence of human demographic pressure was felt through the fact that settlements were becoming more permanently established and densely populated toward the end of the Pleistocene. People in these settlements would have been inclined to bring wild plants with good harvest and eating qualities into closer proximity, and thus take the first steps toward agriculture.
Socioeconomic factors are also considered important as Human Drivers in early agriculture and domestication. As hunter-gatherer groups became more permanently settled in the Late Pleistocene they evolved into more socially and economically complex groups. Socioeconomic complexity is generally associated with the demands for more agricultural production in order to support a non-agricultural segment of the population as well as for the use of the ruling groups within these societies. The emergence of this social organization, and higher population density, combined with the ability to feed larger populations with newly domesticated grains, are plausible as a powerful positive feedback that served to continue and strengthen the course of domestication and agriculture. Continued climate change associated with the expansion of farmed areas, and potentially soil degradation from farming that necessitated even larger land areas and/or more productive domesticated crops (see module 5), would have been additional feedback forces that strengthened the emergence of agriculture. Therefore, drivers and feedbacks are one way to answer the "when and why" questions around the start of agriculture, as a coevolution of human society with changing climate and vegetation. The concepts of drivers, feedbacks and coevolution will be further explored in module 2.2, to explain other stages and transitions in the history of food systems.