"Usefulness" means a great deal more than "reliably repelled invaders". Many civilizations have collapsed or been subjugated and yet produced lasting useful kn

"Usefulness" means a great deal more than "reliably repelled invaders". Many civilizations have collapsed or been subjugated and yet produced lasting useful knowledge and beautiful culture we still use and appreciate today. If they had a crystal ball they no doubt would have reprioritized some things.