"Scarcely more than two generations had tasted the fruits of industrialization when the growth of population was still further accelerated by truly effective death control. The role of microorganisms in producing diseases was discovered. In 1865 the practice of antiseptic surgery began. It serves... as a reasonable demarcation of the beginning of an era filled with related breakthroughs in medical technology: hygienic practices, vaccination, antibiotics, etc. The total effect of this recent series of achievements has been to emancipate mankind more... from the life-curtailing effects of the invisible creatures for which human tissues used to serve as sustenance. Like other prey species newly protected from their predators, we have been fruitful and have so multiplied that we have much more than "replenished" the earth with our kind."