Early Hunter-Gatherer Modifications of Environment for Food

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 Nature and Timing of Agricultural Domestication: Global Patterns

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].

Figure 2.1.1. Grains and ears of the wild ancestor of maize, teosinte, domesticated in the area of present-day Mexico about 6000 years ago (left), a comparison of the plant and seedstalk of teosinte and modern maize (center), and size comparison of teosinte and maize ears (right). Note the relatively large seeds of teosinte that may have called attention to early plant domesticators as a useful species for a staple food, and the true size comparison of the two ears at far right that shows the dramatic increase in size accomplished through domestication and breeding.

Credit: Teosinte photo (left), Matt Lavin; Teosinte/Maize comparison diagram (center), Biosciences for farming in Africa (B4FA) [4]; size comparison photo (right), Hugh Iltis.

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.

Geographical Sites and Ecological Components of Agricultural Domestication

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.

Figure 2.1.2. Map of the crop centers of origin as described by botanist and breeder Nikolai Vavilov: (1) Mexico-Guatemala, (2) Peru-Ecuador-Bolivia, (2A) Southern Chile, (2B) Southern Brazil, (3) Mediterranean, (4) Middle East, (5) Ethiopia, (6) Central Asia, (7) Indo-Burma, (7A) Siam-Malaya-Java, (8) China and Korea.

Credit: Wikimedia Commons: Vavilov-center (Creative Commons CC BY 3.0 [5])

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.

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).

Explaining Domestication using Coupled Human-Natural Systems (CHNS)

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.

Review and Definitions: Drivers, Feedbacks, and Coevolution

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.

Figure 2.1.3 General Diagram of Coupled Natural-Human Systems (CNHS) illustrating potential drivers and feedback processes from human to natural systems and from natural to human systems (blue ovals show examples of these processes). It is understood from module 1 that the human and natural systems themselves consist of multiple social and environmental components, but are represented as solid blocks here for simplicity.

Credit: adapted by Karl Zimmerer and Steven Vanek from a diagram designed by the National Science Foundation Coupled Natural-Human Systems Program

Click for a text description of the Human Natural System image.

Diagram of coupled natural-human systems. At the top of the diagram is the heading "Human to natural drivers and feedbacks: Human system causes changes in the natural system and strengthens existing changes". At the bottom of the diagram is the heading "Natural to Human drivers and feedbacks: Natural system causes change in the human system and strengthens existing changes". From Human System, the arrow flows to an oval with the following items inside: Hunting, Domestication, Fire, Expansion of land under tillage and food crops, City building. There is another arrow from Natural System to an oval with the following items inside: Long-term drought or rainfall increases, Climate warming or cooling, Collapse of wildfire or plant populations. The arrows represent a continuous relationship.

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.

An initial, specific example: Why did agriculture emerge at the end of the ice age?

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.

Figure 2.1.4 Specific example of a coupled human-natural system in a transition from hunting and gathering to domestication and early agriculture, showing what are thought to be a dominant driver (climate change) and a human response that created positive feedbacks in strengthening the transition to agriculture (densification and social organization of human settlements near water sources)

Credit: National Science Foundation Coupled Natural-Human Systems Program

Click for a text description of the Human Natural System image.

Specific examples of coupled natural-human systems. At the top of the diagram is the heading "Human to natural drivers and feedbacks: Human system causes changes in the natural system and strengthens existing changes". At the bottom of the diagram is the heading "Natural to Human drivers and feedbacks: Natural system causes change in the human system and strengthens existing changes". An arrow from Natural System to an oval with the following: 1. Change to warmer climates and more seasonal precipitation, including vegetation changes (late Pleistocene and early Holocene, i.e. end of ice ages). From Human System, the arrow flows to an oval with the following: 2. Increase in the size and density of human population near water and increased social complexity and demand for agricultural products. The arrows represent a continuous relationship.

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.

From the Origins of Agriculture to Challenges and Opportunities for the Future of Food 

Introduction

The development of agriculture as part of food systems in the Anthropocene began with domestication and has continued across millennia among diverse peoples inhabiting a wide variety of the earth’s environments (e.g. the Mediterranean region, the Indus River Valley; southern South America; the Congo River basin; the Island now called Sumatra, and many other highly varied landscapes). The history of agriculture also includes the present: domesticated plants and animals, as well as agricultural management, continues to change. In module 2.2 we will divide an overview of this complex history into four general periods:

1. Domestication/Early farming (10,000 BP-4,000 BP);
2. Independent States, Small Groups, World Trade, and Global Colonial Empires (4,000 BP – 1800/1900 CE);
3. Modern Industrial Agriculture (1800/1900 CE – Present);
4. Recent Quasi-Parallel Agricultural Types and Possible Next Phase (2000 – Present): Agroecological Modernization (e.g., Organic) and Local Environment-Food Systems.

Each of these categories lumps together a lot of variation with regard to the specifics of agriculture and coupled human-natural food systems, and if you have the chance to read in more detail about these phases of the Anthropocene, you'll find a significant and interesting amount of variation among different places and time periods (see the additional readings at the end of the unit).

To continue describing the environment-food systems of each of these four periods, we recall that in module 2.1 we described the long period of hunter-gatherer activities and environment-food systems, which comprised well over 90% of the history of humans as a cultural species. We also looked at plausible drivers and feedbacks in the origins of agriculture and domestication. Here in Module 2.2. We’ll pick up the thread of the environmental and social transformations represented by agricultural origins and domestication. We note that early agriculture, and perhaps a later stage of agricultural development marked the transition to the Anthropocene epoch in which humans became a dominant force in transforming earth's surface and natural systems (see module 1 regarding the Anthropocene).

Key terms and concepts for the history and development of food systems

After its first origins, agriculture spread worldwide through a process known as spatial diffusion. The spatial diffusion of agriculture involved individuals and groups of people gaining access to the ideas, information, and materials of agriculture and other innovations through physical relocation and social interactions. Spatial diffusion can occur through local individual-level human observation and the exchanges of goods and information as well as long-distance trade and organized activities (e.g. group-level decisions to adopt a new planting technology). A brief description and examples of spatial diffusion in early agriculture are given in Table 2.2.1. While agriculture was developed independently in each of the different world geographic areas roughly corresponding to centers of crop domestication (Module 2.1, Figure 2.NN), agriculture then spread widely out of these early centers in a way that was highly influential. Agriculture's diffusion from the Near East to Europe, for example, transformed a wide range of environments and societies. As discussed more below, the spread of crops themselves was often transformative for the environment-food systems to which these domesticates arrived. For example, all the major cuisines we know today rely on food ingredients that were made available as the result of spatial diffusion For example, foods originally from Mexico, such as tomatoes, chili peppers, and maize transformed environment-food systems globally beginning in the 1500s, spreading as far as Africa, India, and China.

The geographic spread of agriculture created both similarities and differences across space and time. On the one hand, sharing the same food crops and sometimes agricultural techniques created commonalities among environment-food systems. The current environment-food system of the country of Peru, for example, is rooted to a large degree in the connections that were forged through spatial diffusion during the Inca Empire that ruled between roughly 1400 and 1532 of the Common Era (CE). On the other hand, differences in environment-food systems also evolved over time as crops and food were subject to the human and natural system influences in each new site to which agriculture spread. One of the main reasons for these differences was the role of people in adapting agriculture to different environments and sociocultural systems.

A few concepts in addition to spatial diffusion are central to understanding the spread of agriculture and its importance, and we introduce them here. These concepts -- adaptation, agrodiversity, and niche construction -- are briefly described with examples in Table 2.2.1, and the term Anthropocene is also reviewed from the standpoint of its relation to early agriculture. The first of these, adaptation, refers broadly to the way in which humans use technical and social skills and strategies to respond to the newness or changes of environmental and/or human systems (e.g. droughts, hillier topography or increased rainfall as crops moved to new areas, climate change). Adaptation and adaptive capacity of human society are a major focus of Module 11.

The use of agrodiversity was also vital to the spread of early agriculture. Agrodiversity is described by the geographer Harold Brookfield and the anthropologist Christine Padoch as human management of the diversity of environments in agriculture and food-growing. Brookfield and Padoch use agrodiversity to describe indigenous farming practices among native peoples, but all knowledgeable farmers actively make use of agrodiversity, even if the technologies may differ greatly. Managing diverse agricultural environments was essential since early farmers produced domesticated plants and animals under new and different conditions. The third concept is that of niche construction, meaning that agriculturalists (and hunter-gatherers) shaped food-growing environments (“niches”) through constructing fields and all kinds of other activities. As a result, adaptation occurring across the wide geographic and historical evolution of environment-food systems involves responses to a range of factors that include both natural ones and those resulting from human activities.

The development of agriculture through the four periods mentioned above has resulted and continues to incur, a wide range of both environmental and social impacts that will be mentioned in the following pages of this module. Environmentally these impacts have altered the biogeophysical systems of our planet, including the land, water, atmosphere, and biodiversity of the earth. As mentioned the idea of the Anthropocene epoch---a distinct geologic epoch defined by drastic human modifications of the earth’s environmental systems---is often tied to agricultural activities. Global environmental sustainability, whether the earth’s systems are operating within limits that will enable long-term functioning, is fundamentally influenced through agriculture, as you’ll see in this module and all the ones to follow.

Period 1: Domestication, Early Farming, and Widespread Impacts (10,000 BP - 4,000 BP) 

We will start our historical summary of environment-food systems by describing domestication and early farming (10,000 BP – 4,000 BP). Widespread environmental and social impacts occurred during this period. New agricultural ecosystems were created and spread along with the use of domesticated plants and animals. These agroecosystems contained distinctive species and populations of plants and animals including domesticates, as well as characteristic insects, mammals, soil biota, and uncultivated plants (such as weeds). In many places, agroecosystems were increasingly established in areas that previously had supported tree cover. During this period in the Near East, China, and Europe, for example, clearing for agriculture led to increased deforestation.

As part of this survey, we ask you to read the short and provocative article by Jared Diamond on the impacts of the diffusion of early agriculture. This should prompt a lot of thinking on your part about the way that the emergence of agriculture affected human societies that we describe further below.

Impacts of domestication and early agriculture were notable not just for natural systems but also on human systems. Both a population explosion and a technology explosion occurred in conjunction with early agriculture. The early farming societies grew in the size of their populations and the use of diverse tools and technologies, including ones that no longer needed to be transported as part of highly mobile hunter-gatherer lifestyles. The growth of population was made possible by the increased productivity of food per unit of land area. Impacts on human health and disease were also notable in this period, though they were not entirely positive. As Jared Diamond points out in the required reading above, there were negative impacts on human health traced to larger settlements and denser human populations (e.g. highly infectious “crowd diseases” such as measles and bubonic plague) and also infectious disease involving transmission from domesticated animals (measles, tuberculosis, influenza). Nutritional stress also ironically increased, with life expectancy actually decreased following domestication and the early development of agriculture.

These negative impacts on humans have led Diamond to refer to agriculture provocatively as “The Worst Mistake in the History of the Human Race”. This title is purposefully provocative, and by way of understanding this "mistake", we should realize that early farmers’ switching to agriculture may have become the most viable option in many places. Agriculture becoming the principal livelihood option would have occurred as local hunted-gathered food sources were overexploited and/or required by population pressure. By the end of this period, the evolution of more complex societies also meant the development of deep class divisions. There the social phenomena of deepened class divisions must also be seen as a product, in part, of the evolution of agriculture. In addition, changing social arrangements from agriculture would tend to create a positive feedback (see the end of module 2.1), along with other factors, in maintaining and deepening the pathway of society towards a greater embrace of an agriculture-based food system.

The model of Coupled Natural-Human Systems (CNHS) can be used to reflect on the above impacts through the integrated perspective of human-environment interactions. Here we can highlight a couple of these interactions. First, widespread deforestation occurred as a result of early agriculture. In addition to changing land cover and ecosystems, it has been postulated that the extent of this deforestation at this time was significant enough to release considerable carbon dioxide (CO₂) and thus to define the beginning of the Anthropocene epoch. As mentioned below other scientists argue the Anthropocene was created more recently. This scientific debate about the Anthropocene epoch has been productive in our understanding of human dynamics and impacts with respect to the environment.

Humans are presumed to have responded to deforestation by increasing their reliance on agriculture, since the removal of forest cover would have reduced the productivity of hunting-gathering activities, creating a second positive feedback that would have deepened the transition to agriculture. The second form of human-environment interaction involved the selection of a relatively small fraction of utilizable plants and animals that become the cornerstones of early agriculture. Since these plant and animal domesticates produced well relative to others, they became relied upon by early farmers, also acting as positive feedback towards the adoption of an agricultural lifestyle. The legacy of this initial selection of certain types of plants and animals demonstrates the important role of contingency and positive feedbacks, whereby initial decisions were amplified and exerted a lasting influence on the Coupled Natural-Human Systems of agriculture. The concepts of feedback are considered further in the subsequent pages and in this Module’s Summative Assessment.

Period 2: Independent States, World Trade, and Global Colonial Empires (3,000 BP – 1800/1900 CE)

The second period of our rapid historical survey encompasses independent states, societies based on small groups, world trade, and global colonial empires and covers roughly 5,000 years between 3,000 BP and 1800/1900 CE. Both positive and negative environmental and social impacts were associated with this period. We can use the coupled system model to illustrate two examples of this period’s characteristic forms of environment-society interactions. The Inca Empire in the Andes Mountains of western South America (from present-day Colombia to Argentina) offers a good example of an independent state with pronounced environmental and social impacts of its agriculture. Ruling from approximately 1400-1532 the Inca state oversaw the building and maintenance of extensive agricultural field terraces and irrigation canals (Figure 2.2.1). These terraces and canals produced sustainable landscapes in the tropical mountain environments of the Andes.

Figure 2.2.1. Terraces and related irrigation works built by the Inca and other early, large-scale agricultural societies are a dramatic example of the transformation of the earth's surface for sustained food production.

Credit: Phil Romans, Flickr [6] (Creative Commons CC BY-NC-ND 2.0 [7])

From the perspective of coupled natural-human systems (CNHS), the terraces and canals of the Inca produced sought-after foods and symbolized Inca imperial power, thus contributing further to Inca capacity to extend these sustainability-enhancing earthworks. The Inca state eventually established terraces and other large-scale agricultural and food transportation works (storage facilities, improved riverbank fields, roads, and bridges) that extended over much of the area of their empire. Environmental impacts of these terraces and other earthworks were beneficial since they stabilized mountain agricultural environments and enabled higher levels of food-growing per unit land area without major damage. Still, we need to remind ourselves that early independent states, such as the Inca, also created environmental problems and often were marked by large social inequalities between rulers and commoners. In other words, just as today, the environment-food systems of non-European peoples could and did attain high levels of sophistication while, at the same time, they were often wracked by significant issues with both environmental and social sustainability (see module 1 for definitions from the "three-legged stool" of sustainability. Similarly important for us to note is that some Inca terraces and canals continue to exist and are still used today as they are in Peru so that they still create a sustainable contribution to food systems at a local scale.

A second example of environmental and social impacts resulting from this period of agricultural diffusion and trade in world history comes from the world trade system established by global colonial empires involving major European powers between 1400 and 1800 (such as the Spanish, British, and French colonial empires). A well-known example of social and environmental impacts from this time period is the exporting of crops and livestock, along with related elements of European environment-food systems, on many areas of the world by these empires. Examples included wheat, sugar cane, alfalfa, cattle, and sheep. These crops and livestock had not originated in Europe but had already diffused there during earlier history, and were common in Europe at the time these empires were expanding. These components of new European colonial environment-food systems were mutually reinforcing, since for example the forage crop alfalfa and introduced European grasses were highly conducive to expanding the raising of cattle and sheep and making new sources of animal food products available to human populations. There were thus reinforcing (positive) feedbacks between the way that these crop species such as alfalfa and grasses were able to "remake" environments and make them more hospitable for European livestock. Sugar cane is another crop that is notorious for remaking the landscapes and social relations in the Caribbean, South America, and the United States, through plantation agriculture and slavery. The case of pasture species and livestock is considered further in this module's summative assessment.

Period 3: Modern Industrial Agriculture (1800/1900 CE – Present)

The third major period in our broad historical summary is modern industrial agriculture, which is the predominant environment-food system today, though it coexists with a significant sector of smallholder agriculture that has incorporated modern industrial techniques to a greater and lesser extent.

Modern agriculture arose in the 1800s and 1900s through a variety of developments in agriculture and in the processing and business of foods. “Industrial” in this description refers to the major role of factory-type processes that are principally large-scale and involve the defining role of technological inputs such as large amounts of freshwater use, chemical fertilizer, pesticides, and “improved” seed that delivers high-yield responses to the other inputs. Industrial is also an appropriate term since this environment-food system has narrowed concentration on a few species of crops and livestock. “Modern” is important in this description since distinct foodways and consumption practices---many based on foods that are highly processed, relatively inexpensive, easy-to-prepare convenience items---that are integral to this environment-food system. Modern is also an important term since it’s estimated this predominant system is based on more changes in the past 100 years than occurred over several hundred and maybe even thousands of years previously.

In much of the world, the advent of the modern environment-food system was provided through the Green Revolution beginning in the 1940s and 1950s. The Green Revolution used science and technology to develop modern crops and agricultural production systems for the countries of Asia, Africa, and Latin America. While it has evolved considerably, the approach of the Green Revolution continues to be used today. The worldwide influence of the Green Revolution suggests one additional term to describe this type of environment-food system, which is “global.” The development of this system, as well as its inputs and impacts, is global in scope. The global characteristics of today’s predominant environment-food system will be evident throughout this module and the others in this course as we place emphasis on the global scale of environmental and social impacts, which relates to the concept of the Anthropocene. In fact, if we consider the bar graphs of the relative areas of wild versus managed land (crops and livestock) globally presented in module 1 (Figure 1.1.4) we can see why some experts prefer to think of modern industrial agriculture, and the related expansion of human populations, as the defining period of the Anthropocene.

Figure 2.2.2. Modern industrial agriculture is a culmination of social and technological processes beginning in the 1800s that sought to increase yields of agriculture for growing human populations by applying fossil fuel energy, mechanization, and advanced crop breeding methods. This photo of a modern grain variety being harvested encapsulates this transformation towards modern agriculture in many ways: the large area of a single grain variety, likely bred and sold by a modern corporation; the extreme mechanical efficiency and speed of grain flowing off the field into a wagon for storage and sales; the need for diesel fuel and associated carbon dioxide emissions to drive the powerful machinery, whose power and efficiency reduces the workforce needed for agriculture.

Credit: Alan Harrison, used with permission from Flickr under a creative commons license

A wide range and mix of environmental and social impacts are associated with modern industrial agriculture. Agricultural mechanization has coincided with a major reduction in the agricultural workforce. In the United States, for example, less than 2% of the population is estimated to be directly employed in agriculture. In the 1870s and 1880s, by contrast, this estimate was 60-80% of the U.S. population. Environmental impacts and human-environment interactions have also been strongly influenced by the widespread use of fossil fuels in modern industrial agriculture.

Fossil fuel use is the foundation for many modern agricultural technologies ranging from tractors and farm machinery (Fig. 2.2.2) to fertilizers and pesticides as well as the energy costs of processing and the large number of “food miles” typically involved in transportation. As the result, energy issues along with greenhouse gas emissions have become a major concern with modern industrial agriculture----as discussed in subsequent modules.

One example of human-environment interaction will suffice in this section since modern industrial agriculture will be examined in detail in many of the modules that follow. (Modules 6, 7, and 8, which focus on agroecology, feature excellent and far more extensive examples.) The widespread use of pesticides and the creation of pesticide-dependent crops and cropping systems are a defining characteristic of this agriculture worldwide. The development of these synthetic products for protecting crops, and potentially the increase in yields associated with solving, if temporarily, a pest problem. Meanwhile, the populations of agricultural pests continue to evolve resistance in response to these applications, an example considered further in module 8. As a result, it is essential that these modern industrial crops and cropping systems (including the use of pesticides) be constantly developed in order to gain a new advantage against the most recently evolved pests.This innovation process in agricultural technology for crops is another example of a positive feedback driving the further industrialization of agriculture.

Period 4: Sustainability Movements Towards the Future of Food: Quasi-Parallel Ecological Modernization and Alternative Food Networks (2000 – Present)

In recent history (since 2000) significant new directions have entered the spectrum of existing environment-food systems. The future of food will depend on these newer systems, in addition to modern industrial agriculture that was introduced on the previous page. The new directions---which we refer to here as “ecological modernization” and “alternative community-based food systems”---are a response to concerns over environmental sustainability, human health, and food safety in addition to the attempt to reinvigorate rural society and address social justice issues, a concept we introduced in module 1 as "social sustainability". Each of these new directions also has its own environmental and social impacts. These impacts are introduced here and then taken up again in module 10.1 when we consider them as "global" and "local community" variants of new, alternative food system types. In both these new directions, a major role is taken by ecological methods and techniques replacing to a significant degree the use of synthetic chemicals. Substantial success can be seen in some cases: for example, organically certified lettuce and carrots with reduced use of synthetic pesticides now account for more than 10% of the land producing these crops in the United States.

Social changes---remember we use this term broadly to refer to economic impacts as well---vary widely in the environment-food systems associated with ecological modernization. Large corporations as well as a substantial number of large family-managed farms, for example, predominate in the large-scale sector of organic agriculture and organic food production and distribution, where these companies and large farms occupy a "quasi-parallel" role to their role in supporting modern industrial food production (previous page). We and other authors describe their style of adoption of organic production techniques as ecological modernization because they seek environmentally sustainable methods as relatively interchangeable replacements for synthetic chemical inputs in modern agriculture (previous page). Ecological modernization also retains modern forms of organization, for example, large scale and efficiency of cropping and shipping of food, corporate management, and sales through mass outlets such as supermarkets. Food distribution companies in this system can offer organic foods at lower prices in the case of fresh vegetables and fruits. This advantage is significant since affordability is a major issue among potential consumers of organic food, and such "corporate organic" foods may be more accessible at the present for a larger proportion of the population. Others argue that issues of cost and accessibility resulting from transitions towards organic and other more ecologically-based ways of managing agriculture merely reflect the artificially low financial, environmental, and social costs of comparable products from the modern industrial food system, for example, the carbon dioxide emitted in the manufacture of fertilizers and pesticides (see module 10). In any case, the rules, regulations, and preferences of human systems designed to foster organic agriculture (such as organic certification and labeling) may be effective in improving the natural system, though the feedbacks to human systems may be ones mostly supporting large agribusiness through positive feedback effects introduced in Module 2.1.

Take for example the case of organic produce such as lettuce and carrots where natural conditions in climatically optimum growing areas (e.g., organic vegetable-growing areas in California) favor the capacity of large corporations and family farms able to access the high-quality land, resource systems (such as water), and deal with the regulatory tasks associated with large-scale national markets. The large scale of these corporate actors becomes a positive feedback driver which strengthens the transition towards this "ecological modernization" mode of a new food production system. This case is considered further in this Module’s Summative Assessment.

“Alternative community-based food networks” is a term that is applied to various smaller though increasingly important types of environment-food systems. We use this term to focus on local environment-food systems. Proponents and activists supporting these types of environment-food systems center much of their attention on the process known as re-localization. This process brings food producers into closer contact with consumers. Local farmers' markets, where farmers sell food directly to consumers, are an example of re-localization. Local environment-food systems are seen as an alternative to the concentrated corporate control of environment-food systems. A major goal of re-localization is supporting small- and medium-scale farmers, including the majority of family-owned farms, as a means of reinvigorating rural life among a range of small businesses---not just a larger number of farms but also the corresponding number of small business that support and benefit rural areas. This interest in “alternative food systems” is committed to increasing the percentage of the “food dollar” that goes directly to farmers. This percentage is estimated currently at 8-10% in modern industrial environment-food systems where a large share of the food dollar goes to food processors and farm input suppliers. For this reason, the local food emphasis in alternative food movements is also sometimes referred to as an emphasis on short food supply chains exemplified by farmers' markets or regional sourcing of food in supermarkets and restaurants. These alternative food systems are presented further in Module 10.

Summative Assessment: Drivers and Feedbacks in the Development of Food Systems

Instructions

Download the worksheet [8] to understand and complete the assessment. You will submit the answers from the worksheet to the Module 2 Summative Assessment in Canvas.

The first part of the worksheet presents a more detailed version of the interaction of human and natural systems at the onset of agriculture at the end of the last ice age, presented at the end of Module 2.1. This is to provide you an example in the use of these diagrams to think about changes in food systems over human history, and it is shown below here as well.

Fig. 2.2.3. Example of human and natural system drivers around domestication in human food systems, to guide responses in the two other examples in the assessment.

Credit: Steven Vanek, adapted from the National Science Foundation

Click for a text description of the Human Natural System image

Heading at the top says, Human to natural drivers and feedbacks: Human system causes changes in the natural system and strengthens existing changes. At the bottom is the heading Natural to Human drivers and feedbacks: Natural system causes changes in the human system and strengthens existing changes. From Human System on the left, an arrow leads to the following items: Humans settle near to water sources in higher population densities, Increase in social complexity, Humans notice and make use of large-seeded wild plants and animals near water for domestication, Increased need for food, Deforestation, and disturbed soils. From Natural system, an arrow flows to the following items: Warmer/drier climates with more seasonal precipitation, Larger seed size in wild plants, Potential domesticated animals drawn to water sources near to humans, Good niches for crops around human settlements. The arrows represent a continuous flow between Human and Natural systems.

Further instructions for the assignment are given in the worksheet. You will need to fill in four questions on the worksheet, some of which have multiple parts.

Completing Your Assignment

Please use this completed worksheet as a guide for taking the Summative Assessment quiz. You do not need to submit your worksheet.