by Steven Jonas, MD, MPH
crossposted on TPJmagazine
Oct. 18, 2009
There have been five Great Extinctions in the history of Earth. And yes, all you creationists out there, according to a great deal of scientific evidence, that is evidence that is based on observation, experimentation and reproducibility, the history of Earth does extend back just a bit more than 4-6000 years.
There have also been about 20 others, big but not so big. The first of the Big Ones occurred at the end of what is called the Ordovician Period, about 450 million years ago. The last Big One, the one that knocked off the dinosaurs and put the mammals on the road to dominance, occurred about 65 million years ago. Now, it seems, we are all of a sudden facing the Sixth Big One. What is the evidence for this?