By growing calorie-rich cereals, farming societies were able to feed many more mouths on the same amount of land: Diamond suggests 100 times more.[17] A recent study demonstrated that our planet is capable of supporting no more than 10 million hunter-gatherers.[18] By 1800 CE, the world’s population had grown to about 900 million with only very basic technology, so this estimate is pretty much spot on.[19] The earth now supports nearly 8 billion people, albeit precariously.
