But China’s people-control system responded, belatedly, and eventually managed to control the spread by physically detaining entire subpopulations in isolation — something it still does. The immediate vehicle of China's ancient people-control system is the ubiquitous Communist Party system of neighborhood committees available to control all entry and exit from premises. That system complements the ancient architecture of single-entrance buildings, compounds, and courtyards, itself an impact of the biome on Chinese culture over centuries. China’s traditional use of human manure (versus animal manure in Europe) as fertilizer nourished the biome and may have contributed to making China, historically, an exporter of plagues internally contained via people-control. Ecological parasitologist Kevin Lafferty in Proceedings of the Royal Society in 2006 first illustrated the impact of the biome on human culture. Karl Marx even praised China’s "recycling" of human manure as opposed to its treatment as sewage in Western cities, which Marx criticized as wastage typical of capitalism. The people-control system removed the urgency in China of developing a vaccine effective enough in immunizing against the virus, as much as it has lent urgency in advanced countries to developing their own effective vaccine(s), precisely because of the absence of the people-control system unique to China.