Population growth is exclusively cultural. See how it's declining in Europe, still growing fast in Africa, etc. Science could change that very fast: birth cont

Population growth is exclusively cultural. See how it's declining in Europe, still growing fast in Africa, etc. Science could change that very fast: birth control isn't available to everyone on earth... yet. But religion could change that fast too. So I guess estimates for the earth population will depend on both science and religion more than anything.