Uncovering tales of transmission: an integrated paleopathological perspective on the evolution of shared human and animal pathogens

This chapter highlights the potential of an integrated paleopathological approach for unravelling the evolutionary history of shared human and animal pathogens. The transfer of pathogens between animals and humans has occurred for millennia and remains a public health issue today, as evidenced by the Covid-19 pandemic. Although the focus has traditionally centred on pathogens transmitted from animals to humans (zoonoses), the direction of transmission is also often the other way (reverse zoonoses). The best way to understand the cross-speciestransfer of pathogens is by investigating the conditions that make it possible for anew host, whether human or animal, to be infected. As societies transitioned from hunting and foraging to herding and farming, and from living in rural to urban settings, and in increasingly industrialised environments, dramatic changesoccurred in their relationships with animals. These changes had major impacts on pathogen evolution. In particular, the new opportunities for transmission affected pathogen virulence and distribution. In this chapter, the factors driving transmission of Taenia tapeworms, Mycobacteria, Plasmodium falciparum, Brucella,Burkholderia mallei and the morbilliviruses in domestic environments will be investigated. Evidence will be drawn from paleopathology, historical sources, molecular analysis, paleoenvironmental data, and medical/veterinary clinical literature. This approach helps explain why these pathogens became problematic when and where they did, and identifies factors that are likely to contribute to future outbreaks. The chapter will conclude with a reflection on the ways an interdisciplinary understanding of past diseases provides insights for current and future epidemics.