Corpses as Repositories of Information and Funerals as Information Centres: Why Natural Selection Favours the Bereaved

ABSTRACT

Numerous species investigate and alter their behaviour around the corpses of conspecifics. However, morbid behaviour creates multiple risks including exposure to disease, predation, and elevated stress levels. Although some causes for morbid behaviour have been postulated, it is not clear if there are adaptive benefits for this reasonably common behaviour that occurs across species. Growing support for information centre theory suggests that conspecifics around a corpse may benefit from shared information. We hypothesise that corpses are repositories for information and that congregations around them are information centres where crucial knowledge about the environment and predators can spread among individuals and groups. We call this the funeral hypothesis. The death of an individual may trigger a myriad of emotions (e.g., fear, anger, and sadness) and behaviours (e.g., congregating, not eating, and aggression) in conspecifics. Because these responses are conspicuous and costly, we interpret them as honest signals prompting other individuals, groups, and sometimes heterospecifics, to gather around the signallers and obtain information about the cause of death via visible and olfactory cues such as wounds or grievous injuries, absence or presence of predators, age of the deceased, and decomposition. This information is then transmitted across multiple levels of complex societies from the individual to different groups. The costs of interacting with corpses are balanced by consolation of bereaved or stressed individuals, enhancing social bonds, facilitating the renegotiation of social positions, and gaining knowledge of threats in the environment. We provide a review linking these concepts and suggest hypotheses generated by the framework.