biostudies-literatureAshby BSwiss National Science Foundation1153-1169https://www.ebi.ac.uk/biostudies/studies/S-EPMC9322624biostudies-literatureUnknown76(6)Social contacts can facilitate the spread of both survival-related information and infectious diseases, but little is known about how these processes combine to shape host and parasite evolution. Here, we use a theoretical model that captures both infection and information transmission processes to investigate how host sociality (contact effort) and parasite virulence (disease-associated mortality rate) (co)evolve. We show that selection for sociality (and in turn, virulence) depends on both the intrinsic costs and benefits of social information and infection as well as their relative prevalence in the population. Specifically, greater sociality and lower virulence evolve when the risk of infection is either low or high and social information is neither very common nor too rare. Lower sociEvolution; international journal of organic evolutionSocial information use shapes the coevolution of sociality and virulence.PMC9322624187058Ashby BFarine DRfalseSocial information use shapes the coevolution of sociality and virulence.Social contacts can facilitate the spread of both survival-related information and infectious diseases, but little is known about how these processes combine to shape host and parasite evolution. Here, we use a theoretical model that captures both infection and information transmission processes to investigate how host sociality (contact effort) and parasite virulence (disease-associated mortality rate) (co)evolve. We show that selection for sociality (and in turn, virulence) depends on both the intrinsic costs and benefits of social information and infection as well as their relative prevalence in the population. Specifically, greater sociality and lower virulence evolve when the risk of infection is either low or high and social information is neither very common nor too rare. Lower soci2022-01-01T00:00:00Z2022 Jun2025-04-18T15:36:28.902Z2025-04-07T02:19:58.758ZS-EPMC93226243542070410.1111/evo.14491