Every year half a million children die of diarrhea. There are so, so many people in the world, who are capable of joy and suffering, who "we" don't care much at all. However I have a feeling that "we" might be joining that group eventually.

Still, it’s vastly fewer now relative to the total number of children born than any previous time in human history. It could be even fewer had birth rates begin to drop instantly as a response to child mortality dropping dramatically even in most developing countries, rather than with a few-generation delay.