Hunting and gathering activities were the primary way for humans to feed themselves from their natural environments during 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 the 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.