The environment became an issue as humans met the advent of new technology and industry following World War II. The post-war focus on improving our quality of life resulted in more production and more consumption. People expected our standard of living to continue to improve and the pie, which is the size of the economy, to continue to grow.

The short- term prospects have been good. However, there is a problem: the primary elements of natural resources, arable land, ground water, forests, marine fisheries, and petroleum, are ultimately finite, and therefore not subject to endless economic growth. As population and consumption continue to grow, our resources left to be harvested are shrinking and the long-term prospects are not promising. As a result, we have begun a frantic search for answers to the issue: how do we accelerate economic development while preserving the environment?

The human species has been living on Earth for at least 40,000 years, which is but an instant in the Earth's 4.6 billion-year history, and perhaps our most outstanding success story is our steady conquest of the environment. Fossil evidence explains how our way of life developed, based in our control of "nature." With that control, of course, populations have grown and threaten the quality life that everyone wants.

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During approximately three quarters of our 40,000-year existence, humans survived by hunting and fishing and by gathering edible wild plants. These early humans lived in small groups of 50 or less and were nomadic in the sense that when food became scarce, they picked up their few possessions and moved on.

The earliest hunter-gatherers survived by having expert knowledge of their natural surroundings as they discovered that a variety of plants and animals could be eaten and used for medicines. Subsequently, these nature dwelling people had three energy sources: sunlight captured by the plants and animals they ate, fire, and their own muscle power. Although the sexes shared work, food, and social power in these groups, the men eventually specialized in hunting and the women in gathering. Thus the societies were highly cooperative and depended upon nature's resources for their survival.

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What is most interesting is that these nomadic groups consciously attempted to keep their populations in balance with the food supply. Such population controls included abstention from sexual intercourse, infanticide, herbal contraceptives, abortion, late marriage, and prolonged breast-feeding of infants to inhibit ovulation. Furthermore, there was a high infant mortality rate and an average life expectancy of about 30 years, thereby allowing for very slow population growth.

Despite their small populations and limited energy sources, they began to have some impact on the environment as their societies became more advanced. Advanced hunter-gatherers eventually used fire to convert forests into grasslands and they also contributed to the extinction of some large game animals such as woolly mammoths and European bison just to name a few. Due to the hunter and gatherer societies' small numbers, nomadic lifestyle, and dependence on their own muscle power to modify the environment, their environmental impact was minimal. As a result, these societies trod lightly on the Earth as they were not capable of doing more.

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Approximately 10,000 to 12,000 years ago, a cultural shift occurred as there was a gradual move from a lifestyle based on nomadic hunting and gathering groups to one of settled agricultural communities. Within these agricultural communities, people learned how to domesticate wild animals and cultivate wild plants.

Early agricultural communities practiced several farming techniques to cultivate crops. One of the techniques used was called slash and burn cultivation. This type of farming was practiced primarily in tropical regions as they burned and cleared small patches of forests. Then the ashes were used to fertilize the nutrient poor soil.

In addition to the slash and burn technique, these farmers also used shifting cultivation. As their cleared plots had been used for several years, the soil became depleted of nutrients. Therefore the growers would move and clear a new plot, allowing the old plot to be reinvaded by the forest. Each abandoned plot had to be left unplanted for 10-30 years before the soil became fertile enough to grow crops again. These techniques resulted in a sustainable cultivation of the land.

Furthermore, these growers grew only enough food to feed their families, what we call subsistence farming. Their dependence upon human muscle power and crude tools kept their plots small and their impact on the environment minimal. However, about 7,000 years ago, humans invented the metal plow, which was pulled by domesticated animals. This allowed farmers to cultivate larger plots of land. In addition, farmers further increased crop production by diverting water from nearby streams into hand-dug ditches and canals to irrigate crops.

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As farming became more sophisticated, the emergence of agriculture-based urban societies had major results, affecting much more than the food supply:

By using domesticated animals to haul loads and perform work, increased the average energy use per person.

As the food supply became more reliable and larger, population increased.

People cleared increasingly larger plots and built irrigation systems to transfer water from one place to another.

A surplus of food was grown, which allowed people to diverge from farming and specialize in other vocations such as weaving, tool making, and pottery.

The formation of villages, towns, and cities became practical, which served as centers for trade, government, and religion.

Conflict between societies became more common as ownership of land and water rights became a valuable economic resource. As armies and their leaders conquered large areas of land, they forced the powerless people into slavery to do the hard work of farming the land and building the irrigation systems.

Competition for land, water, and power led to male-dominated societies as females were forced to give up their power to male warriors in order to gain protection from aggressors for themselves and for their children.

The survival of wild plants and animals, once vital to the hunter-gatherer societies, no longer mattered. Therefore, wild animals that competed with livestock for grass and feeding on crops were killed and wild plants that invaded crop fields were eliminated.

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Environmental Impact of Progress:

As agricultural civilizations grew in population, people cut down more forests and plowed up large expanses of grassland to provide more food, fuel, and building supplies. This extensive land clearing degraded and destroyed the habitats of many wild plants and animals, thus leading to their extinction.

In addition, many of the cleared lands were poorly managed, which resulted in soil erosion, salt buildup in irrigated soils, and overgrazing of grasslands by domesticated livestock. Fertile lands turned into deserts as topsoil washed into streams, lakes, and irrigation canals, thereby rendering them useless. Consequently, the degradation of soil, water, forests, grazing land, and wildlife were major factors in the downfall of early civilizations.

The aim of these new agriculturally based societies became to tame and control nature and to gain power by controlling other humans. Thus this era sets the stage for many of today's environmental problems.

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At the heart of all environmental problems is world population growth. We can look at each of the natural resources we need in order to live (and live well), but a critical question is, "who is we?" Today 6.1 billion people share the planet. Twice as many as 40 years ago. And the numbers are growing. Approximately 77 million babies are born every year.

The real question is: How many people can the Earth support? Within 50 years, there could be between 7.9 and 10.9 billion people, according to United Nations population projections. What will be the quality of their lives? Everyone will need resources - food, water, clothing, energy, and shelter at the very least - that come from living systems suck as rivers, forests, croplands, and oceans. How can people's needs be met without exhausting those systems?

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