The sixth mass extinction, primarily driven by human activities, is more dire than previously anticipated, with entire branches on the tree of life now disappearing, finds a new study published in the Proceedings of the National Academy of Sciences [5] Sept. 18. Researchers from Stanford University and the National Autonomous University of Mexico, led by Gerardo Ceballos and Paul Ehrlich, assessed 5,400 genera of terrestrial vertebrates, including 34,600 species. The staggering results: 73 genera have become extinct since 1500 AD. This rate of extinction surpasses the last million years by 35 times. In other words, in just five centuries, human actions have triggered a surge of genus extinctions that would have otherwise taken 18,000 years. The researchers refer to this as a "biological annihilation." (Earth.com [6])
Each of the Earth's five major extinction events [7] wiped out between 75 and 90 percent of the world's species over a period of 2.8 million years or less. (IE [8])
