One of the most interesting and surprising facts I've learned in recent years concerns human extinction.  Neil DeGrasse Tyson put it like this in Death by Black Hole:  "Fact is, humans cannot really kill Earth.  Our planet will remain in orbit around the Sun, along with its planetary brethren, long after Homo sapiens has become extinct by whatever cause."  That's a fairly nonchalant way of referring to the near certainty of humans going extinct.  It's a fascinating and somewhat scary thing to think about, but it's based on a few pieces of solid reasoning:  Assuming we don't kill ourselves with bullets or nuclear bombs, there's a good possibility we'll be wiped out by a global pandemic.  If that doesn't happen, there's a good chance we've trashed the earth enough to make it nearly inhospitable to life.  But even if those two things don't happen, there's still the fact that no species in the history of our planet has lived longer than a few million years.  People like to talk about our galaxy's impending collision with the Andromeda galaxy in 4 billion years, or the death of the sun in 5 billion years.  But current thinking suggests that humans will go extinct way before that time.  And that's a crazy thing to think about. #science