ABSTRACT
Individual living things die, which is sad, but far sadder is the ending of entire species. Today, a frightening number of species are on their deathbeds. This chapter examines how the current extinction crisis is a threat not just to the world’s wild species but also to the future of humans. Very long time periods are defined in geology by the intervals between planetary-scale catastrophes in which a substantial portion of living species were exterminated, and life was forced to survive very difficult conditions. Recent domination of Earth by humans is dramatically degrading the natural environment (hence the environmental crisis, of which global warming is the most publicized aspect) as well as damaging both ecosystems and their constituent species (hence the biodiversity crisis). There are three basic ways that humans endanger other animals: unintentionally (primarily by habitat destruction), deliberate elimination of species that are perceived as competitors or sources of danger, and overharvesting for resources (especially for food).
