"Either Stone Age man was a technological wizard, who carefully removed his technological achievements so as not to upset his inferior progeny, or our population dwindled from a once astronomical size to the mere three billions of today."

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There are millions of different species of animals and plants on earth--possibly as many as forty million. But somewhere between five and fifty BILLION species have existed at one time or another. Thus, only about one in a thousand species is still alive--a truly lousy survival record: 99.9 percent failure!

— David M. Raup