[maddog55]

The earth is 4.5 billion years old, there's been 5 mass extinction events:

-End Ordovician (444 million years ago; mya) -Late Devonian (360 mya) -End Permian (250 mya) -End Triassic (200 mya) -Cretaceous period (66 mya)that killed off the dinosaurs

There will be more to come... Mankind won't be around after the next one

[metmom]

Some of mankind is working to ensure it to happen.