SINCE the human species first became fully conscious of the natural world, nature has usually seemed unassailable, and abundant with plant and animal life, from mountains, to oceans, to continental prairies.

Over the course of the 20th century, however, this view has changed. Man’s power over nature, assisted by machines, has grown, and human population has increased exponentially. For centuries, nature has been in retreat in the face of human settlement, but in the last 50 years, destruction of the natural world has picked up speed.

Scientist believe that when human development and agriculture reduce the natural world, the loss is not simply a matter of size. The remaining natural areas, it is believed, harbour fewer species and complex ecosystems. Scientists who study “biodiversity” posit that many wild species are becoming extinct, and that this extinction of wild species — many of them still unknown or not well understood — bodes ill for the future of the planet.

Since the dawn of agriculture, human survival has been based on the domestication for food purposes of wild plants. Yet, many plant species are being destroyed in the wild, before their food or medicinal value can be assessed. The continuation of wild or partially-wild varieties of plants such as corn is necessary to the future health of domesticated varieties.

In addition, whole ecosystems, such as riverine estuaries, coral reefs, montane forests, and the creatures that live in them are under stress due to human-caused pollution, or over-development. Yet, these ecosystems, in all their marvellous complexity, cleanse water of pollutants, provide the air we breathe, and produce much of our food, making human existence possible. In effect, the vast web of biological diversity with its millions of species on this planet, is what has made human survival possible, and human life fulfilling.

Three themes crop up in everybody’s lists of why diversity matters. They are utilitarian values such as medicine and agriculture; ecosystem services; vital functions such as the continued production of atmospheric oxygen; and moral, ethical and aesthetic values.

Just as most of us don’t know how our telephones, TV sets, and computers work, we really have only the vaguest idea of where our foods and medicine come from. Harder yet to understand is the significance for our very existence of species and ecosystems which seem to just sit there and provide no obvious product for us to eat, use as fuel, or stock our medicine chests.

Vaguer is still the calm sense of joy and simple belongings most urbanites experience with a simple walk in a wood-lot, through a meadow, or along a clean shoreline. Yet these three categories of the effects of the living world on human life are absolutely crucial to modern and future human life on planet earth.

-Excerpts taken from Biodiversity on a Changing Planet.