David Grinspoon Quote
The Big Five extinctions are simply slightly more intense than the sixth- or seventh-largest declines, and you could just as easily discuss the Big Seven or Big Ten, depending on how you sliced up the data. This tally refers only to extinctions since the Cambrian explosion, the sudden proliferation of complex animal life 542 million years ago, and it neglects extinction events that happened earlier, during several billion years of evolution dominated by simpler organisms. So, though the changes occurring right now are often referred to as the beginning of a possible sixth extinction, take this with a grain of salt. It’s good to focus attention on the dramatic loss of species currently under way and how this fits into the history of extinction events on Earth, but this also reinforces an incomplete picture of Earth’s dynamic history. Post-Alvarez,
The Big Five extinctions are simply slightly more intense than the sixth- or seventh-largest declines, and you could just as easily discuss the Big Seven or Big Ten, depending on how you sliced up the data. This tally refers only to extinctions since the Cambrian explosion, the sudden proliferation of complex animal life 542 million years ago, and it neglects extinction events that happened earlier, during several billion years of evolution dominated by simpler organisms. So, though the changes occurring right now are often referred to as the beginning of a possible sixth extinction, take this with a grain of salt. It’s good to focus attention on the dramatic loss of species currently under way and how this fits into the history of extinction events on Earth, but this also reinforces an incomplete picture of Earth’s dynamic history. Post-Alvarez,
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About David Grinspoon
His research focuses on comparative planetology, with a focus on climate evolution on Earth-like planets and implications for habitability. He has also studied, written and lectured on the human influence on Earth, as seen in cosmic perspective.
He has published four books, Venus Revealed, which was a finalist for the Los Angeles Times book prize, Lonely Planets: The Natural Philosophy of Alien Life, which won the 2004 PEN literary award for nonfiction, Earth in Human Hands, which was named one of NPR's Science Friday "Best Science Books of 2016" and Chasing New Horizons: Inside the Epic First Mission to Pluto, co-authored with Alan Stern. He is adjunct professor of Astrophysical and Planetary Science at the University of Colorado, a former Fellow of the Institute for Cross-Disciplinary Engagement at Dartmouth College and a former Distinguished Visiting Scholar in the College of the Environment at Wesleyan University.