 Professor Paul Wignall of the University of Leeds and an expert on mass extinctions told me that the Permian was the greatest crisis that life on Earth has ever suffered. Only in the past two decades has the cause of the Permian extinction been understood. It was speculated that an asteroid impact may have been the trigger, but more recent research by Professor Wignall, geologists, and other scientists around the world have revealed the true trigger came from deep within the Earth.