Societies, including those of humans, have evolved multiple ways of dealing with death across changing circumstances and pressures. Despite many studies focusing on specialized topics, for example necrophoresis in eusocial insects, mortuary activities in early human societies, or grief and mourning in bereavement, there has been little attempt to consider these disparate research endeavours from a broader evolutionary perspective. Evolutionary thanatology does this by adopting an explicit evolutionary stance for studies of death and dying within the sociological, psychological and biological disciplines. The collection of papers in this themed issue demonstrates the value of this approach by describing what is known about how various nonhuman species detect and respond to death in conspecifics, how problems of disposing of the dead have evolved in human societies across evolutionary time and also within much shorter time frames, how human adults' understanding of death develops, and how it is ultimately reflected in death-related language. The psychological significance and impact of death is clearly seen in some species' grief-like reactions to the loss of attachment figures, and perhaps uniquely in humans, the existence of certain psychological processes that may lead to suicide. Several research questions are proposed as starting points for building a more comprehensive picture of the ontogeny and phylogeny of how organisms deal with death.This article is part of the theme issue 'Evolutionary thanatology: impacts of the dead on the living in humans and other animals'.
Evolutionary thanatology benefits from broad taxonomic comparisons of non-human animals' responses to death. Furthermore, exploring the sensory and cognitive bases of these responses promises to allow classification of the underlying mechanisms on a spectrum from phylogenetically ancient to more derived traits. We draw on studies of perception and cognition in invertebrate and vertebrate taxa (with a focus on arthropods, corvids, proboscids, cetaceans and primates) to explore the cues that these animals use to detect life and death in others, and discuss proximate and ultimate drivers behind their capacities to do so. Parallels in thanatological behaviour exhibited by the last four taxa suggest similar sensory-cognitive processing rules for dealing with corpses, the evolution of which may have been driven by complex social environments. Uniting these responses is a phenomenon we term 'animacy detection malfunction', whereupon the corpse, having both animate and inanimate attributes, creates states of fear/curiosity manifested as approach/avoidance behaviours in observers. We suggest that integrating diverse lines of evidence (including the 'uncanny valley' effect originating from the field of robotics) provides a promising way to advance the field, and conclude by proposing avenues for future research.This article is part of the theme issue 'Evolutionary thanatology: impacts of the dead on the living in humans and other animals'.