People are no different than any other life form on this planet; our propagation is dictated by our access to food, water, habitat and available mates. Were the population to be overburdensome, the cost of living would increase to the point where housing and food would be such that only the well-to-do would attempt to start families, let alone large ones. Although welfare disrupts this natural selection, that our societies are still wealthy enough to offer provisional care says a lot about the continued abundance of resources still available.