One of the main aspects is that of habitat destruction. Of course our planet is continually changing, causing habitats to be altered and modified, but these tend to happen at a gradual pace. This allows most species to adapt to the changing environment, where only a slight impact may take place. However, when changes occur at a fast pace, there is little or no time for an individual species to react and adjust to the new circumstances. This cause disastrous results, and for this reason, rapid habitat loss is the primary cause of species becoming endangered. Nearly every region of earth has been affected by human activity. It is difficult for an individual to recognize the effects that humans have had on specific species (Brook p.385). It is even more difficult to predict human effects on individual species and environments, especially during one lifetime.

Plants and animals are responsibly for a variety of useful medications. In fact about forty percent of all prescriptions written today are composed from the natural compounds of different species (Ehrlich p.121). These species not only save lives, but they contribute to a prospering pharmaceutical industry worth over $40 billion annually. Unfortunately, only 5% of known plant species have been screened for their medicinal values, although we continue to lose up to 100 species daily. The Pacific yew, a slow-growing tree found in the ancient forests of the Pacific Northwest, was historically considered a "trash" tree. However, a substance in its bark taxol, was identified as one of the most promising treatments for ovarian and breast cancer (http://www.hort.purdue.edu/newcrop/NewCropsNews/94-4-1/taxol.html). Additionally, more than 3 million American heart disease sufferers would perish within 72 hours of a heart attack without digitalis; a drug derived from the purple foxglove.

Disease, pollution, and limited distribution are more factors that threaten various plant and animal species. If a species does not have the natural genetic protection against particular pathogens, an introduced disease can have severe effects on that specie. For example, rabies and canine distemper viruses are presently destroying carnivore populations in East Africa (Campbell). Domestic animals often transmit the diseases that affect wild populations; demonstrating again how human activities lie at the root of most causes of endangerment. Pollution has seriously affected multiple terrestrial and aquatic species, and limited distributions are frequently a consequence of other threats; populations confined to few small areas due to of habitat loss, for example, may be disastrously affected by random factors.

Plant and animal species and their ecosystems form the basis of America’s multi-billion dollar, job-intensive tourism industry. They also supply recreational, spiritual, and quality-of-life values as well. Each year over 108 million people in the United States participate in wildlife-related recreation including observing, feeding, and photographing wildlife. Americans spend over $59 billion annually on travel, lodging, equipment, and food to engage in non-consumptive wildlife recreation (Ehlrich p.207)

The hypothesis is by changing the way the human race lives many animals could be saved from endangerment.

Some topics in this essay:
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