World's Sixth Mass Extinction May Be Underway

World's sixth mass extinction may be underway: study - Yahoo! News "Mankind may have unleashed the sixth known mass extinction in Earth's history, according to a paper released by the science journal Nature."

"Palaeobiologists at the University of California at Berkeley looked at the state of biodiversity today, using the world's mammal species as a barometer. Until mankind's big expansion some 500 years ago, mammal extinctions were very rare: on average, just two species died out every million years. But in the last five centuries, at least 80 out of 5,570 mammal species have bitten the dust, providing a clear warning of the peril to biodiversity."

"The authors admitted to weaknesses in the study. They acknowledged that the fossil record is far from complete, that mammals provide an imperfect benchmark of Earth's biodiversity and further work is needed to confirm their suspicions. But they described their estimates as conservative and warned a large-scale extinction would have an impact on a timescale beyond human imagining. "Evolution of new species typically takes at least hundreds of thousands of years, and recovery from mass extinction episodes probably occurs on timescales encompassing millions of years.""

""So far, only one to two percent of all species have gone gone extinct in the groups we can look at clearly, so by those numbers, it looks like we are not far down the road to extinction. We still have a lot of Earth's biota to save," Barnosky said."