Quality of life
A high quality natural environment brings psychological benefits: contact with the natural environment can uplift the human spirit; increase people's sense of place and well-being; and has been shown to improve both physical and mental health and generally contribute to quality of life (for further information).
The following are some of the benefits of biodiversity: [seems so general that these could be in the introduction rather than this page]
Our food
Over 30% of the global food crop production depends on insect pollination (Centre for Agri-Environmental Research, Reading University). A total of about 3,000 plant species, 200 of which have been domesticated, are used worldwide as a food source. However, just 20 of these plants currently provide more than 80% of our food. In order to maintain the high level of production such consumption demands, plant breeders frequently turn to the wild relatives of domestic crops in search of desirable genetic traits such as resistance to disease or drought; so wild plants are a valuable reservoir of genetic diversity. A smaller number of animal species provide human food but the scale is often enormous. For example, in 1989 world landings of fish and other aquatic life forms totalled 99.5 mega-tonnes, 70% of which was for human consumption. (Chivian, E. and Bernstein, A. - ed (2008) Sustaining Life How Human Health Depends on Biodiversity Oxford University Press)
Our health
In addition to food, many of our drugs and raw materials for manufacturing also originate from plants or animals. Globally 3.5 billion people rely on plant-based medicine for primary health care, and in the USA a quarter of medicines prescribed are based on compounds originally found in plants. (Chivain, E. and Bernstein, A. - ed (2008))
Our homes
Many industrial materials, such as fibres, resins, dyes, waxes, pesticides, lubricants and perfumes come from plant or animal sources. Trees provide more than 3.8 million cubic metres of wood annually for use as fuel, timber or pulp.
Our lives
There is now a rapidly growing leisure industry which relies on the living world. For example, eco-tourism, based on the observation of wild animals and wilderness habitats, generates between US$100 billion and $200 billion annually, much of it in needy developing economies.
While we can readily identify uses of biodiversity which directly support human life and are commercially valued, we often overlook a host of ‘hidden' functions of living organisms which are equally vital to human well-being. Foremost among these are ecosystem services, such as nutrient cycling, soil formation, watershed protection, waste disposal, pollination, oxygen production, carbon sequestration and climate regulation.
There are also many species which are not exploited themselves but have indirect value because they are food for economically valuable species. For example, molluscs and crustaceans are eaten by edible fishes. Other non-use values derive from the as yet undiscovered possibilities for future uses of wild flora and fauna, such as new drugs from plants and genes usable in breeding new characteristics into crops and domestic animals.
A totally different set of non-use values attaches to the significant contribution of wild organisms to human art, literature and religion.