The relationship between wealth and health is actually somewhat controversial: the so-called Preston curves demonstrate a dramatic relationship between health and economic prosperity up to about a Purchasing Power Parity of US$3,000 per capita per year [11] . However, there are cheap, cost-effective approaches to population health (such as vaccination, clean water, and sewage disposal) that may not be affected by the increase in Purchasing Power Parity. These approaches were relatively more important than economic development per se in early 20thcentury interventions in developed countries, and they are likely to be more important for infl uencing health among developing country populations today than simple economic growth. On the other hand, high-intensity technological improvement rather than economic growth may be more important to health in rich countries compared with developing countries.