The average lifespan of a civilization is 336 years. via @LukaKemp & @BBC pic.twitter.com/qmnFDyPr1U— The Long Now Foundation…
The average lifespan of a civilization is 336 years. via @LukaKemp & @BBC pic.twitter.com/qmnFDyPr1U
— The Long Now Foundation (@longnow) February 28, 2019