Comparative Evolutionary Thanatology of Grief, with Special Reference to Nonhuman Primates

Comparative Evolutionary Thanatology of Grief, with Special Reference to Nonhuman Primates James R. Anderson Kyoto University Abstract: The impact of the dead on the living is considered from an evolutionary comparative perspective. After a brief review of young children’s developing understanding of the concept of death, the interest of looking at how other species respond to dying and dead individuals is introduced. Solutions to managing dead individuals in social insect communities are described, highlighting evolutionarily ancient, effective behavioral mechanisms that most likely function with no emotional component. I then review examples of responses to dying and dead individuals in nonhuman primates, with particular reference to continued transport and caretaking of dead infants, responses to traumatic deaths in wild populations of monkeys and apes, and a detailed case report of the peaceful death of an old female chimpanzee surrounded by members of her group. The emotional correlates of primates’ reactions to bereavement are discussed, and some suggested evolutionarily shared responses to the dead are proposed. Key words: thanatology, death, dying, emotions, social insects, nonhuman primates, chimpanzees Thanatology can be broadly defined as the study of death and dying, and researchers from a wide range of disciplines are thanatologists. Among others, studies in medicine, biology, psychology, anthropology, palaeontology, sociology and philosophy all contribute new knowledge about the antecedents, causes, and consequences of death (e.g. Exley 2004; Haldane 2007; Klarsfeld et al. 2003; Kübler-Ross 1969; Pettitt 2011; Powner et al. 1996). Concerning people’s understanding of death, psychologists generally agree that the typical human adult’s concept of death comprises at least four sub-concepts or “components” (Speece 1995). “Irreversibility” refers to the understanding that dead organisms cannot recover or be brought back to life. “Inevitability” (or universality) refers to the understanding that all living things eventually die, including oneself. “Non-functionality” (sometimes referred to as finality) refers to the understanding that a dead organism cannot behave, feel, perceive, think, or process information. “Causality” refers to understanding what underlies death, i.e., that it results from serious damage to or the breakdown of one or more vital bodily organs. Japanese Review of Cultural Anthropology, vol. 18-1, 2017 174 James R. Anderson In their investigations of how an adult-like concept of death is formed, developmental psychologists have shown that young children’s and adults’ views differ in several ways (for overviews see Slaughter 2005; Speece 1995). The differences concern the four recognized components of death understanding: universality (or inevitability), irreversibility, non-functionality, and causality. For example, instead of understanding the inevitability of death, young children typically believe that they and/or significant others in their lives will not die. Contra irreversibility, young children may also believe it is possible to come alive again after dying; being dead is akin to being asleep. Also for young children, a dead individual may still be sentient, able to perceive sensory stimulation such as people talking to them or touching them. Finally, children’s understanding that death is caused by damage to vital organs is preceded by a phase of prioritizing external causes, such as accidents, or killing. As will be seen later, these four components of death understanding can provide a useful perspective from which to look at the issue in other species, in particular other primates. Children typically achieve a mature understanding of death by the age of 10-11 years, when they are approaching Piaget’s stage of “formal operations” and show increased competence at dealing with abstract concepts (Inhelder and Piaget 1958). A grasp of the biological causes of death is the last component to be acquired, with the others being understood a few years earlier (Slaughter and Griffiths 2007; Speece and Brent 1984). Some evidence suggests that children with personal experience of bereavement – resulting from the demise of a family member, for example – have a more mature appreciation of irreversibility and non-functionality, along with an enhanced overall understanding of death. Depictions of death in drawings may also differ as a function of bereavement experience in childhood (Bonoti et al. 2013). Alongside academic and applied interest in how modern humans deal with death and dying, some thanatologists embrace evolutionary approaches. For example, palaeontologists and physical anthropologists attempt to piece together the emergence and development of corpse disposal practices among prehistoric and later hominids (e.g., Pettitt 2011). Biologists and ethologists study other species’ responses to dead and dying individuals from the perspectives of natural selection and underlying biological and psychological mechanisms (Anderson 2016; Archer 1999; King 2016). In the remainder of this article I review some thanatological research on nonhuman animals, with a particular focus on behavioral and emotional responses to corpses in nonhuman primates. I then propose a tentative comparison of some responses to the dead observed in modern humans and in our nearest evolutionary neighbors, chimpanzees. My overall aim is to elucidate some commonalities between how humans and nonhumans deal with their dead, and to argue that increased knowledge of the impact of the dead on living nonhumans can help our understanding of the evolution of modern humans’ concepts of and reactions to death. James R. Anderson Grief in Nonhuman Animals 175 In their investigations of how an adult-like concept of death is formed, developmental Managing the Dead is Evolutionarily Ancient: Social Insects psychologists have shown that young children’s and adults’ views differ in several ways (for overviews see Slaughter 2005; Speece 1995). The differences concern the four Decaying corpses are a potential source of disease, especially if the deaths have arisen recognized components of death understanding: universality (or inevitability), irreversibility, from infection. The living may have better survival prospects if they avoid contact with non-functionality, and causality. For example, instead of understanding the corpses. Such avoidance is relatively easy to achieve for species or groups that have no inevitability of death, young children typically believe that they and/or significant particular fixed “home base” within their home range or territory. In primates, for others in their lives will not die. Contra irreversibility, young children may also believe it example, if a group member dies at or near one of the group’s sleeping sites, the corpse is possible to come alive again after dying; being dead is akin to being asleep. Also for can be avoided simply by moving away to another part of the home range and sleeping young children, a dead individual may still be sentient, able to perceive sensory at another location until risks associated with the proximity of the corpse have stimulation such as people talking to them or touching them. Finally, children’s diminished. Indeed, monkeys and apes typically leave dead individuals – with the understanding that death is caused by damage to vital organs is preceded by a phase of exception of dead infants (see below) – either precisely at or near to where they died, prioritizing external causes, such as accidents, or killing. As will be seen later, these after periods of time ranging from a few minutes to several hours (see below). Modern four components of death understanding can provide a useful perspective from which to hunter-gatherers have also been recorded to abandon camp following the death of group look at the issue in other species, in particular other primates. members (e.g., Lee, 1979). In nonhuman primates, by the time the surviving group- Children typically achieve a mature understanding of death by the age of 10-11 years, members return to where they last encountered the corpse the chances are it will have when they are approaching Piaget’s stage of “formal operations” and show increased disappeared, due to a combination of biotic degradation processes and scavengers competence at dealing with abstract concepts (Inhelder and Piaget 1958). A grasp of the feeding on and dispersing it (but see Anderson 1984, for exceptions). biological causes of death is the last component to be acquired, with the others being The situation is different for species that congregate permanently (or semi- understood a few years earlier (Slaughter and Griffiths 2007; Speece and Brent 1984). permanently) at a fixed site, such as nests of social insects. Indeed, it has been Some evidence suggests that children with personal experience of bereavement – suggested that cues to the origins of funerary activities in earlier human societies are resulting from the demise of a family member, for example – have a more mature likely to be found where groups lived in a relatively fixed place (Pettitt 2011). The nests appreciation of irreversibility and non-functionality, along with an enhanced overall and hives of social insects provide another example of where corpse management is understanding of death. Depictions of death in drawings may also differ as a function of important. These enclosed environments, often associated with high population bereavement experience in childhood (Bonoti et al. 2013). densities

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