Skeletal evidence for the emergence of infectious disease in bronze and iron age northern Vietnam.

Human skeletal evidence for the emergence of chronic infectious disease in northern Vietnam is examined. The sample includes the remains of 192 individuals representing the Mid-Holocene and Bronze to Iron Ages. The objective is to see if the transition from sedentary, foraging, coastally oriented economies to centralized chiefdoms with attendant development and intensification of agriculture, trade, metal technologies, warfare, and population increase was accompanied by an emergence of and/or increase in infectious disease. It was found that skeletal evidence for infectious disease was absent in the Mid-Holocene, while over 10% of the Metal period sample exhibited lesions consistent with either infectious disease or immune system disorders. Factors potentially contributing to the emergence of infectious disease in northern Vietnam in the Metal period include: increased contact with bacterial or fungal pathogens either directly or by way of vertebrate and/or arthropod vectors; higher levels of debilitation and/or decreased levels of immunocompetence in the Metal period; and evolution of pathogens present in Mid-Holocene human hosts into more virulent forms in the Metal period. The first two factors may be related to historically and archaeologically documented major demographic (Han colonizing efforts) and economic (agricultural intensification) changes in the region during the Metal period.