The existence of life is the defining feature of Earth, and diversity is the most striking aspect of life on Earth. Since the origins of life three billion years ago, the biological diversity of life, or its biodiversity, has been on an upward but jagged trajectory along which the formation of new species has exceeded, with but few exceptions, the loss of existing species. The exceptions were major extinction events, attributable to catastrophic occurrences such as meteor impacts and globally massive volcanic activity.
Earth now has on the order of five million species, all descended from the same ancestor. This biodiversity has been an enduring source of wonderment and scientific mystery from the era of great naturalist-explorers, such as Darwin and Wallace, to the present. Earth also has seven billion people who, in meeting their needs for food and energy, have become a globally…
