Using paleodata to map parasite diversity throughout Holocene

Parasites make up a significant portion of the global biomass and are integral to the healthy functioning of modern ecosystems. Despite their importance today, past changes in parasite distribution and diversity remain largely unexplored due to their limited preservation potential in the fossil record. Using information from more than 700 archaeological and paleoparasitological studies, we compiled a comprehensive database of parasite finds from the Holocene to address this knowledge gap. Our aim was to provide high-resolution spatial and temporal data on parasite occurrences to facilitate their use beyond archaeological literature, e.g., in macroevolutionary analyses and in ecological modelling of future trends in parasite distribution. The database includes more than 3,000 occurrences, which, along with information on their locality, age, taxonomic identity of the parasite and its potential hosts within relational database framework, allows users to build comprehensive profiles of parasite diversity on different geographical scales or spanning a particular time period. The majority of parasite finds consist of resistant eggs or trace evidence of intestinal helminths, such as nematodes (particularly genera Ascaris and Trichuris) and flatworms (genera Dibothriocephalus, Taenia and Fasciola), recovered from sediment samples and coprolites associated with human settlements or burials. Most parasite finds have been identified to at least the genus level and are mostly concentrated in the late Holocene period, with a significant increase in occurrences at the start of the Middle Ages. Using various modelling approaches, we demonstrate that the presence of the most common genera of intestinal parasites in archaeological record throughout the Holocene correlate with increases in human population density and seasonality.