For healthy adult people, the really big thing we can foresee are ways of intervening in the ageing process, either by slowing or reversing it.

The greatest existential risks over the coming decades or century arise from certain, anticipated technological breakthroughs that we might make in particular, machine super intelligence, nanotechnology and synthetic biology. Each of these has an enormous potential for improving the human condition by helping cure disease, poverty, etc. But one could imagine them being misused, used to create powerful weapon systems, or even some kind of accidental destructive scenario, where we suddenly are in possession of some technology that's far more powerful than we are able to control or use wisely.

Machine intelligence is the last invention that humanity will ever need to make.

The first ultraintelligent machine is the last invention that man need ever make, provided that the machine is docile enough to tell us how to keep it under control.

Are you living in a computer simulation?

In the next century, we will be inventing radical new technologies - machine intelligence, perhaps nanotech, great advances in synthetic biology and other things we haven't even thought of yet. And those new powers will unlock wonderful opportunities, but they might also bring with them certain risks. And we have no track record of surviving those risks. So if there are big existential risks, I think they are going to come from our own activities and mostly from our own inventiveness and creativity.

Far from being the smartest possible biological species, we are probably better thought of as the stupidest possible biological species capable of starting a technological civilization - a niche we filled because we got there first, not because we are in any sense optimally adapted to it.