But humanity a) survives long term, and b) he predicts extremely long-lived, stable societies between calamities. It's much more realistic to assume that no hum

But humanity a) survives long term, and b) he predicts extremely long-lived, stable societies between calamities. It's much more realistic to assume that no humans would survive a global extinction level event on Earth. Life itself would probably survive all but the most extreme events, but it would have to evolve into intelligent life for another species to attempt to spread life beyond earth.