Diseases, human history and co-evolution with pathogens

Peter Gluckman and Tatjana Buklijas

Liggins Institute, The University of Auckland, New Zealand

Leprosy and kuru may at first glance seem to be diseases with little in common, except, perhaps, their large historical significance, declining prevalence and the fact that both affect only humans. Although leprosy is chronic and poorly contagious, in medieval Europe and the Middle East the appearance of the sick and the stigma of the disease provoked so much fear that unprecedented social strategies were invented to exclude them from communities. In the West, leprosy began to disappear by the 1700s-possibly because of the plague’s selective effect against the immunologically weak. Yet long after Hansen’s description of Mycobacterium leprae in 1873 and despite the availability of effective treatment, this obligatory parasite adapted almost exclusively to humans remains prevalent. Kuru, in contrast, probably first appeared in the early twentieth century within the Fore linguistic group in the highlands of New Guinea who consumed their dead relatives at mortuary feasts. As the ritual was mostly performed by women and children of both sexes, men remained mostly unaffected. By the time the physician and anthropologist D. Carleton Gajdusek  first described the disease in the Western medical press (1957), the numbers of affected were falling because of the decline in cannibalism. But the real sensation came a few decades later when kuru was shown to be transmitted through infectious protein particles that were named prions. (more…)