About This Project

Do primates understand death? Can they grieve? When a primate baby dies, often the mother will carry its corpse, in some cases for weeks. Some suggest this is evidence of grief. But we can look for other markers of grief, like those that humans show: depression, loss of appetite and lethargy. In this study, we will conduct a field study of macaques to quantify mothers' behavioural responses to the deaths of their infants and search for evidence of grief.

Ask the Scientists

What is the context of this research?

Every living animal dies. However, until recently, little empirical research has addressed how animals respond to death. This is remarkable because understanding how and why animals respond in the ways that they do to the deaths of others can address fundamental questions about the evolution of emotion, such as: Do animals respond emotionally to death?

Grief is an emotion. Emotions are temporary states that are brought about by events in the physical and/or social environment that prime an individual to respond in an adaptive manner. The study of emotions in animals has been historically avoided not least because it is impossible to ask an animal how s/he feels. However, we can search for similar indicators of grief in primates that are homologous to those found in humans.

What is the significance of this project?

This study will be the first prospective study about how primates respond to death. Although this field is expanding rapidly, hypothesis testing remains rare. Systematically collected data are absent. To our knowledge, no studies have collected prospective data systematically to address questions about primates’ emotional response to the deaths of others.

Beyond being the first study of this kind, the question of the importance of death and dying for the evolution of minds goes beyond solely empirical research. The answers have implications for broader debates over the relationship between emotion and cognition, the nature of animal cognition and sentience, and thus also the ethical standing and treatment of animals.

What are the goals of the project?

This project will ask whether primate mothers grieve the loss of their infant. We will do this by searching for the same behavioural indicators of grief in humans, such as stress, depression and loss of appetite.

Our study will be completed on free-ranging, provisioned macaques at the Caribbean Primate Research Centre, Puerto Rico, a long-term research colony. Each year, approx. 300 infants are born on the island. Births are seasonal: our study will begin at the start of the birth season, lasting 3 months.

We will conduct focal observations on mothers. In the unfortunate instance that an infant dies or disappears, we will compare the behaviour of the mother and two control females: one with a similarly-aged infant, and a similarly-aged female without an infant.