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I've long been keenly interested in what nonhuman animals (animals) may know about death and dying, including what they know about their own condition and that of others. I've also been very interested in comparing how traditional science and citizen science inform these queries. This is why a fascinating essay by Dr. Susana Monsó titled "What animals think of death: Having a concept of death, far from being a uniquely human feat, is a fairly common trait in the animal kingdom," caught my eye.
Monsó begins by describing what "playin' possum" means, in this case in the presence of a coyote, animals I know very well. She writes, "When the Virginia opossum feels threatened, she plays dead. Lying on the ground, curled up into something resembling the foetal position, with her eyes and mouth open and her tongue hanging out, she stops responding to the world." Her breathing and heart rate are very low and she pees, defecates, and produces a secretion from her anal glands that is extremely putrid. She looks like she's dead and scans around to see what the coyote is doing. The coyote would rather have a fresh meal and leaves, and the opossum gets up because feigning death worked.
Monsó also writes, "Despite the persuasive performance of death, no one would assume that the opossum herself believes that she’s playing dead. Her behaviour is most likely automatic, and the opossum no more knows that she’s disguising as a corpse than a stick-insect knows that she looks like a stick."
As a field ethologist who has seen opossums playing dead many times, I was struck by Monsó's use of the phrase "most likely automatic." In her next sentence she writes, "While this presupposition is probably right, it would nevertheless be wrong of us to assume that there’s nothing to learn about animals’ concept of death from the opossum’s display." (My emphasis) I agree that playing possum—called thanatosis—and how a coyote might respond can tell us a good deal about what other animals think about death.
Here are a few snippets from Monsó's essay that I hope will lead to much needed further discussions about what nonhumans know about death and dying.
- "The human concept of death is not necessarily the only concept of death." I agree, and also that perhaps she is correct when she notes that humans have "an overly complex view of this concept."
- "In minimal terms, the concept of death is simply made up of two notions: non-functionality and irreversibility." What this boils down to is that an individual needs to somewhat know that a dead member of her species doesn't do what live individuals do and that this is a permanent state.
- "This minimal concept of death requires very little cognitive complexity and is likely to be very widespread in the animal kingdom." I tend to agree but I remain uncertain about what a dying animal is actually thinking about themselves or another animal who is dying or dead.
Opossums, dogs, and disgusting odors
Monsó goes on to write about the different stages of predation through which coyotes (and likely other predators) go through and how opossum thanatosis plays into each. She correctly notes that a predator's experience of disgust due to the incredibly noxious odors a death-feigning opossum expels may help to explain why playin' possum works. Pretty much anyone who has come across a corpse knows that there is a disgusting strong and unpleasant odor that indicates death.
When I've written about what dogs might know about death and dying, I've speculated that a composite signal made up of some unique combination of visual, auditory (for dying animals), and olfactory cues might tell an individual who is dying and others around them that something "new" and unique is happening—a process we call "dying"—and after an animal dies another composite signal that lacks any acoustic cues indicates that something else has happened—an event we call "death." However, I'm not sure that this says much at all about if an individual actually knows anything about dying and death—that they have a concept of death—as we cash it out.
Along these lines, Monsó writes, "most animals come with a hard-wired tendency towards necrophobia, which is a stereotypical aversion to corpses that is not mediated by a concept of death. This means that most animals are disgusted by the smell or the appearance of corpses, even if they do not understand what a corpse is." She also notes that this is not a complete explanation of why death-feigning has evolved, but it is a reasonable explanation of why a corpse-looking and smelling opossum might be avoided.
Monsó ends with an evolutionary explanation of why thanatosis might have evolved. The simple answer is because it works, and it's possible that opossums have no concept of death and aren't trying to look like a corpse. She also argues that perhaps playing dead is innate and "predators’ concept of death was the likely selection pressure that shaped these displays." This, of course, tells us what might be going through the minds of predators.
As I wrote above, I found Monsó's piece to be very thought-provoking and I agree with her conclusion: "The concept of death should also be counted among those characteristics to which we can no longer resort to convince us of how very special we are. It is time to rethink human exceptionalism, and the disrespect for the natural world that comes with it." I agree, but I also feel the jury is still out about what animals actually know and dying and death and how it fits into our own concepts of dying and death. This is not to say that other animals don't have their own sorts of concepts of dying and death that matter to them.
I look forward to further comparative studies and discussions about nonhumans' concepts of dying and death because they also might tell us about many other aspects of what they think and feel in a wide variety of contexts. And we also can learn about the other animals who interact with dying and dead individuals and if and how they played a role in the evolution of concepts of dying and death as Monsó suggests for opossums and coyotes.
One thing that's for sure is that the minds and hearts of other animals are far more active than many people believe, and there's a huge database that clearly shows that they have highly evolved cognitive and emotional capacities that could well include having concepts of death and dying. It's very exciting that there's still so much to learn.
References
Bekoff, Marc. What Do Animals Know and Feel About Death and Dying?
_____. Do Dogs Know They're Dying? (Was Sadie really trying to tell her human companion that Oscar was dying?)
_____. Do Dogs Know They're Dying? What Citizen Science Tells Us. (While the jury is still out, around 20 percent of people think that dogs know.)
