Mounting evidence from species as diverse as cats and dolphins indicates that humans are not the only species that grieves over the loss of loved ones. On a research vessel in the waters off Greece’s Amvrakikos Gulf, Joan Gonzalvo watched a female bottlenose dolphin in obvious distress. Over and over again, the dolphin pushed a newborn calf, almost certainly her own, away from the observers’ boat and against the current with her snout and pectoral fins. It was as if she wanted to nudge her baby into motion—but to no avail. The baby was dead. Floating under direct sunlight on a hot day, its body quickly began to decay; occasionally the mother removed pieces of dead skin and loose tissue from the corpse.When the female dolphin continued to behave in this way into a second day, Gonzalvo and his colleagues on the boat grew concerned: in addition to fussing with the calf, she was not eating normally, behavior that could be risky for her health, given dolphins’ high metabolism. Three other dolphins from the Amvrakikos population of about 150 approached the pair, but none disrupted the mother’s behavior or followed suit. As he watched the event unfold in 2007, Gonzalvo, a marine biologist at the Tethys Research Institute in Milan, Italy, decided he would not collect the infant’s body to perform a necropsy, as he would usually have done for research purposes. “What prompted me not to interfere was respect,” he said. “We were privileged to be able to witness such clear evidence of the mother-calf bond in bottlenose dolphins, a species that I have been studying for over a decade. I was more interested in observing that natural behavior than interrupting it by abruptly interfering and disturbing a mother who was already in obvious distress. I would deﬁne what I saw as mourning.” Was the dolphin mother truly grieving for her dead calf? After all, the mother might have become agitated only because the strange, inert status of her calf puzzled her.
Tradition dictates that it is soft-hearted and unscientiﬁc to project human emotions such as grief onto other animals. Gonzalvo may have been correct in his judgment that the mother dolphin was mourning. In the past few years a critical mass of new observations of animal responses to death has bubbled to the surface, leading to a startling conclusion: cetaceans, great apes, elephants, and a host of other species ranging from farm animals to domestic pets may, depending on circumstances and their own individual personalities, grieve when a relative or close friend dies. That such a broad range of species—including some quite distantly related to humans— lament the passing of loved ones hints that the roots of our own capacity for grief run very deep indeed.
Since Charles Darwin’s day, two centuries ago, scientists have debated hotly whether some animals display emotions beyond those associated with parental care or other aspects of survival and reproduction. Darwin thought that, given the evolutionary connection between humans and other animals, many emotions must be similar across species. He granted to monkeys, for instance, grief and jealousy, as well as pleasure and vexation. But the attribution of emotions such as these to animals fell increasingly out of mainstream scientiﬁc favor.
By the early 20th century the behaviorist paradigm held sway, with its insistence that only observable behavior of animals, not their interior lives, could be studied with rigor. Gradually the scientiﬁc embrace of animal emotion has revived, thanks originally in part to anecdotes from long-term field studies on large-brained mammals. From Tanzania, Jane Goodall recounted in heart-wrenching detail young chimpanzee Flint’s decline and death from grief only weeks after the death of his mother, Flo. From Kenya, Cynthia Moss reported that elephants attend to dying comrades and stroke the bones of deceased relatives. Field biologists and anthropologists began to ask questions about whether, and how, animals mourn.
To study and understand grief among animals, scientists need a deﬁnition that distinguishes it from other emotions. Whereas “animal response to death” embraces any behavior by an individual following the death of a companion animal, researchers may strongly suspect grief only when certain conditions are met. First, two (or more) animals choose to spend time together beyond survival-oriented behaviors such as foraging or mating. Second, when one animal dies, the survivor alters his or her normal behavioral routine—perhaps reducing the amount of time devoted to eating or sleeping, adopting a body posture or facial expression indicative of depression or agitation, or generally failing to thrive. For his part, Darwin conﬂated grief with sadness. But the two differ, primarily in intensity: the grieving animal is more acutely distressed, possibly for a more prolonged period. This two-part deﬁnition is imperfect. For one thing, scientists lack a metric for evaluating exactly what counts as “more acutely distressed.” Should the criteria for grief differ according to species, and might grief in other animals assume forms that are difﬁcult for humans to recognize as mourning? The data are not yet available on these questions. Furthermore, mothers or other caretakers that constantly provide food or protection to infants that subsequently die cannot be said to have met the ﬁrst criterion (going beyond survival-oriented behaviors), yet they remain among the strongest candidates for suffering survivor’s grief. Future studies of animal mourning will help reﬁne this deﬁnition. For now, it furthers our critical assessment of responses made by animals when others around them die. For instance, baboon and chimpanzee mothers in wild African populations sometimes carry the corpse of their dead babies for days, weeks or even months—a behavior that on the surface of things might look like grief. But they may not exhibit any signiﬁcant outward indicator of agitation or distress. When the animals carry on with their routine behaviors, such as mating, their behavior does not meet the criteria for mourning.
- Scientific American Magazine, Barbara J. King