Stemming the Flow: Information, Infection, and Social Evolution

Abstract

Social information and socially transmitted pathogens are governed by social structure, and also shape social interactions. However, information and infection are rarely investigated as interactive factors driving social evolution. We propose exactly such an integrative framework, drawing attention to mechanisms of social phenotypic plasticity for information spread and pathogen control.

Keywords: evolutionary trade-off; network plasticity; social behavior; social decision-making.

Figure I

A Framework Outlining the Feedback Loop between Individual Behavior, Social Structure, and Social Transmission, both Beneficial and Detrimental. Changes in individual status (informed and/or infected) lead to different patterns of social interactions. Informed individuals are seen as valuable interacting partners (1), whereas infected individuals are avoided by others or reduce their own interaction rates (2). These changes in social relationships lead to structural changes at the network level that affect social transmission. More or less cohesive networks affect the rate of transmission, which depends on the system. Simple contagion is linked to the number and strength of social relationships, whereas complex contagion depends on the proportion of social connections with informed or infected individuals (3). Network topology then mediates social transmission, which affects individual status. We propose a framework that integrates the two mechanisms, simultaneously examining information and pathogen flow as explicit and opposing entities, with emergent patterns of social behavior, and thus social connectivity, reflecting a trade-off between them. We exemplify this trade-off through a survival indicator: survival increases with increasing information gain and reduced pathogen exposure, and vice versa (4). Macaque images, credit: Delphine Vaufrey.

Figure I

Empirical Studies Demonstrating That Social Avoidance Is an Important Strategy for Controlling Pathogen Spread. (A) Trinidadian guppies (Poecilia reticulata) (credit: Darren Croft), (B) mandrills (Mandrillus sphinx) (credit: Paul Amblard-Rambert), (C) Caribbean spiny lobsters (Panulirus argus) (credit: Donald Behringer), and (D) house mice (Mus musculus domesticus) (credit: Barbara Koenig).

Figure 1

Evidence for Network Plasticity and Its Effects on Information and Pathogen Transmission. The behavioral mechanisms underlying human (A), ant (B), and non-human primate (C) social contact are shown. When a pathogen is introduced into a system and detected, infected and non-infected individuals usually change their contact rates. This leads to changes in network structure, such as increasing the number of subgroups, which affects the efficiency of pathogen transmission (D). Conceptually, the feedback is similar across the three systems depicted. The communication system can also change, as exemplified by both ants and humans, from a targeted and local contact-based modality to a global or more broadly disseminated modality (e.g., public information such as online communications or pheromone trails/clouds). Asterisks refer to the effect of pathogen-induced changes in network properties. *P < 0.05; **P < 0.01. The networks in (B) and graph in (D) were reproduced from [5] with permission from AAAS. The images of macro- and micro-organisms were created with BioRender.com.