Originally Posted by notabook

If we were to see a comet or asteroid this century that is large enough to cause global climate change and wide-spread extinction, humanity would probably be destroyed in the process. There is some small chance you could survive the initial impact (depending on the size of comet or asteroid) but the many years of the sun being blocked out is going to destroy almost any chance of you able to successfully find food/and or hunt for survival. If you somehow managed to get the world to work together, you may just be able to save enough humans by putting them deep underground.

Even then? repopulating the planet with such a small genetic pool seems very unlikely. You may be able to sustain a small pool of humans for x number of years, but eventually (and probably sooner than later) the remainder of the human population will dwindle and dwindle until there simply just isn?t enough genetic variance to sustain a healthy population. More and more kids will start being born with more and more genetic abnormalities until the species eventually inbreeds itself into extinction. And that is story of how Moses saved Egypt from the robots.