Reciprocal Relationships Between Humans and the Environment

Michele Perch

Homo erectus, or standing, upright humans, date back to at least 3.2 million years ago (Ponting 1992, p. 18).  Homo sapiens, or “wise ones”, are predecessors of modern humans, and evolved around 30,000 years ago (Ponting 1992, p. 19).  Even before humans were considered intelligent, they adapted to their environment, shaping it to their advantage.  Many may believe that early humans lived off of the land without significantly affecting it.  However, humans have been disrupting their habitats since the start of human evolution.  This same theme is existent in modern society, as many of the same human motivations and behaviors that existed over a million years ago are still reflected in current societies.  While our predecessors manipulated their environments, the environment also shaped their behavior.  There are strong connections between humans’ effects on the environment and the environment’s effects on humans.  Primitive humans provide evidence that once humans alter the environment, it too can affect the course of human nature, starting a perpetual cycle (for better or for worse).

The development of man-made fires created by humans 50,000 years ago, for instance, are likely to have shaped the climate and animal populations of Australia.  Small fires set for hunting wiped out the forests in which megafauna lived.  The fires cleared most of the vegetation, which collected rainfall and then released it back into the atmosphere through transpiration.  With fewer plants, the megafauna eventually went extinct, and the monsoon rainfalls were significantly weakened, as less and less water was transported back into the atmosphere.  Australia is now an arid continent, and those who live there have adapted to the change (Grossman 2002). 

The extinction of the megafauna and transformation of Australia’s climate show that even seemingly trivial human practices can affect the environment, and further influence human behavior.  Perhaps more telling is the example of the feedback loop between fire and human intelligence.  There is some evidence that human-induced fires date back to 1.6 million years ago, far before Homo sapiens evolved.  Starting a fire is a fairly complex process, and thus it is widely believed that intelligence is essential for creating fires. Counterevidence comes from Kenya, however, where archeologists found large orange circles in the earth from 1.6 million years ago that appear very similar to the marks that local people’s man-made fires leave.  Comparisons of earth affected by natural fires (lightning, bush fires, etc.) also suggest that humans created the fires.  The possibility that fire dates back to Homo erectus leaves one to wonder whether intelligence is really a requisite for the creation of fire.  On the other hand, perhaps humans were already beginning to become intelligent 1.6 million years ago.  We are left to wonder whether fire necessitates intelligence, or if, perhaps, fire helps the development of intelligence and language.  It is most likely a combination of both, in which fire and intelligence work together to create our modern perceptions of human nature and human culture (McCrone 2000).

In the time of the Kenyan fires, language had likely not yet developed.  Tools deliberately burned in the fires suggest that humans were “producing something very practical, rather than living within a culture with language in which every activity becomes invested with elaborate rituals and beliefs” (McCrone 2000, p. 34).  Continuation of activities and behaviors through the generations should indicate that the members of the society were intelligent and capable of language.  Groups of early humans who discarded their tools immediately after using them were not involved in any kind of lasting culture.  However, their life spans were also very short, making it difficult to pass on information through the generations, perhaps even including information on how to start a fire.  Fire, however, is capable of lengthening life expectancy, because it provides protection against the cold and predators, and provides a means in which to cook food.  Once humans became more intelligent and could create fires with ease, it likely provided the opportunity for more social gatherings.  While these gatherings may have started out as groups simply warming themselves, cooking, or eating together, it may have initiated the development of language and culture.

As language develops, it has the capacity to perpetuate and expand very quickly.  Even simple grunts and groans could improve coordination in situations such as hunting.  In turn, the average human life span has the potential to get much longer as humans become more effective hunters.  According to a Darwinian approach, natural selection may have weeded out those who were unable to coordinate and thus, hunt with the group and reap the benefits.  Those who were more intelligent were more likely to survive and pass on the traits of intelligence (such as larger brain size).

Just as fire and intelligence may have perpetuated the other, there is evidence that population growth and intensified food production were caught in a feedback loop thousands of years ago, forever changing primitive human behavior.  Hunter-gatherers used land to kill and gather food sources, but they rarely stayed in one place for very long.  Once they had used the land for all of its resources, they moved on.  Hunter-gatherers valued leisure highly and spent very little time looking for food.  There was no need to preserve food or have many personal belongings, because it interfered with their mobile lifestyle (p. 20).  Hunter-gatherers knew to keep their populations to a minimum so that all of the members of their group could be adequately fed.  “Twins, the handicapped, and a proportion of female offspring” may have been killed selectively, and elderly or sick people may have been abandoned (Ponting 1992, p. 23).  However, these practices were not effective enough to prevent population growth.  Eventually, the population grew so much that groups were forced into less than optimal climates for hunting or gathering. 

Population pressure ultimately led to the development of agriculture.  However, agrarian societies promoted further population growth.  This is another instance, similar to the fire examples, in which we see humans changing their environment, and as a result, the environment changes human behavior - and in this case - the course of human society.  Humans did not develop agriculture deliberately.  Rather, conditions (population pressure) forced them to intensify the process of finding adequate amounts of food.  For example, humans that would otherwise forage for wild plants might focus on cultivating certain wild plants in order to have enough to eat.  Eventually, random foraging and hunting turned into agriculture and raising cattle, about 10,000 years ago, when the population hit maximum capacity for nomadic lifestyles (Ponting 1992, p. 42). 

Agriculture was not an easier option for the nomadic peoples.  It meant taking on risk, since fewer plants and animals were cultivated and bred, and it also meant many more hours of work a day in a culture that valued leisure.  The one advantage of agriculture was that food could be grown in high quantities and in small spaces, and in a time when food competition had become more prevalent, this was an increasingly critical benefit.  As more intensified forms of food production began to develop, population pressure continued to increase since more people had access to food.  In turn, agriculture became more and more important, and thus, more prevalent.  Once early forms of food production began to intensify, there was no going back, with high populations and minimal space.  Intensified food production has had profound impacts on the way in which human societies function.  It created a concept of ownership where previously there had been none.  While hunter-gatherers had equal access to plants and animals, the cultivation of plants and domestication of cattle created a system in which individuals or organizations controlled food production.  Since there was not a need for every individual to produce food, this left room for specialization within society.  Thus, surplus food (food that did not go directly to farmers’ families) was distributed to members of the society.  Religious and political ruling groups likely controlled the circulation of food, taking the most, and then allocating it to various parts of society.  Intensified food production and distribution perpetuated hierarchical structures that are ubiquitous in societies all over the world. 

This process likely took a very long time to complete, and certainly full-fledged hierarchies were not present right at the start of the transition to agriculture.  However, human practices always affected the environment, from hunting and gathering to full-scale agriculture.  Altered habitats caused humans to change their behavior in turn, and the cycle became perpetual.  We also see this with fire, in which humans may have started with primitive intelligence, subsequently created fire, and then developed further intelligence, allowing them to create fires more frequently and for more purposes.  Primitive human beings were involved in some of the same cycles that we experience in modern day.  We contribute heavily to climate change, and in the same vein, climate change will continue to affect us through various natural disasters, health effects, and political conflicts caused by food scarcity.  Luckily, early humans were able to adapt to environmental changes without much consequence, and often times, with benefits.  Hopefully we will also have the ability to adapt effectively to the changes occurring in our environment as well.



Grossman, Robert. 2002. “Aboriginal Climate Change.” Radio Interview. NPR.

McCrone, John. 2000. “Fired Up” New Scientist. 20 May 2000.

Ponting, Clive. A Green History of the World: The Environment and the Collapse of Great Civilizations. New York: St. Martin's Press, 1992.

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last updated 1/25/10