Much the same reasoning applies to the diversity of genes and ecosystems. We do not fully understand their importance, we did not make them and they are not ours to dispense with. The second major reason to conserve biological diversity is what it does for us. In a world where people are plagued by hunger, disease, ethnic and religious strife, social upheaval, political oppression and extreme disparity in wealth, it is legitimate to ask why should we be concerned about the loss of biological diversity rather than concentrating on pressing human needs, such as economic development and national security. Every breath we take, every bite of food we eat and every drop of water we drink comes from the diversity of life.
Ecosystems perform services essential to our existence.
They break down pollutants, build the soils on which humankind depends, protect coastlines from storms and maintain the composition of our atmosphere. Species from forests and the sea are the most exciting new sources of medicines. For example, a new potent anti-cancer medicine called taxol came from the bark of Pacific yew trees that have become rare because of logging. Taxol is particularly effective against breast and ovarian cancers, which have taken the lives of many thousands of Jews, such as the late comedian Gilda Radner. The only way to ensure that our medicine cabinet will be well-stocked is to maintain biological diversity.