Humans actually benefit in a large number of ways from the protection of endangered species and thus continuing biodiversity.

Firstly, the diversity of life and living systems is considered by many scientists to be a necessary condition for human development. We live in a world built on a carefully balanced ecosystem in which all species play a role, and the removal of species from this can cause negative consequences for the whole ecosystem, including humans.（解释展开）

There is also the potential for almost any species to hold currently-unknown future benefits to humans through products they could provide. One example of this is the scrub mint, an endangered plant species which has been found to contain an anti-fungal agent and a natural insecticide, and thus holds great potential for use that benefits humans. （举例展开）

Endangered species have also been known to hold the key to medical breakthroughs which save human lives. One example of this is the Pacific yew (a tree species) which became the source of taxol, one of the most potent anticancer compounds ever discovered.（举例展开）

Conclusion：Thus the preservation of endangered species helps to protect humans, as this means plants and animals continue to play their specific role in the world's ecosystem which humans rely on, and may hold the key to scientific and medical breakthroughs which can greatly benefit humanity. All this could be lost through the careless extinction of plant and animal species.

An environment with a great diversity of plant and animal species in it can act as a source for art and entertainment, enriching the lives of humans. Thus the preservation of endangered species is an important part of ensuring this diversity continues to exist so people can enjoy and be inspired by the many varied kinds of life on this earth.（解释展开） A good example of this is the re-introduction of the grey wolf into Yellowstone Park in the United States (where it had previously become extinct due to human action), which added to the biodiversity of the region and caused a greater influx of tourists into the park.（举例展开）

Conclusion：People enjoy being surrounded by different kinds of nature, and so protecting endangered species is an important part of protecting human enjoyment.

Protecting endangered species can harm humans. Protecting endangered species by definition means restricting activity that humans would otherwise want to do,(解释) be it by turning woodland into farmland, turning meadows into housing developments, or by preventing us from eliminating 'pest' species which kill livestock or damage crops.（列举） For example, the reintroduction of the grey wolf into Yellowstone Park has increased once more the risk to livestock in the region and caused economic harms to ranchers there. （举例）

Some of these species may even pose a threat to human lives, which may have been why they were hunted to extinction in the first place.In any case, less agricultural land and less land for housing can only mean higher food and housing costs (due to their decreased supplies in the face of a rising human population) for people, which has a detrimental impact upon human life.（解释）

Species extinction is a part of the natural world. Within evolution species naturally go arise and later become extinct as they struggle to adapt to changing environments and competition with other species.（解释） This be regarded as a part of the 'survival of the fittest' which drives evolution. Most extinctions that have occurred did so naturally and without human intervention. It is, for example, estimated that 99.9% of all species that have ever lived are now extinct, and humans have existed at the same time as only a fraction of these species.（举例）

Therefore it cannot be claimed that species going extinct will somehow upset the delicate natural balance or destroy ecosystems. Ecologists and conservationists have in fact struggled to demonstrate the increased material benefits to humans of 'intact' wild systems over man-made ones such as farms and urban environments, which many species simply adapt to. Therefore any claims that humans causing the extinction of other species are somehow acting 'un-naturally' or 'immorally' or that they are risking ecological collapse as a consequence are mistaken, as they fail to understand that extinction occurs as a natural fact and that ecosystems adapt accordingly. No other species acts to prevent species besides itself from becoming extinct, and therefore again allowing another species to die out is in no way 'un-natural.'