It's important to note that not only humans feel grief in the wake of loss. New research is showing that grief is more universal than we might have previously thought, existing across the entire animal kingdom. In an interview with NPR, Barbara J. King discusses her book How Animals Grieve and the implications of this new field of study:
On the methodology of researching animal emotions: In the book I tell stories — some gleaned from the scientific literature, others from interviews with animal caretakers — of individual animals and how they expressed love for a relative or friend, then grieved when that other animal died. Rather than writing about grief in the collective or as an abstract, I describe what happened when a gorilla silverback lost his closest gorilla friend, when the house cat Willa lost her sister Carson, when a dolphin mother observed in Greek waters lost her infant. It's from those stories that patterns, and hypotheses to test, emerge.
"I also describe field scientists who use GPS collars to track elephants' movements then closely observe the behavior of individuals as they approach the body of a dead matriarch, or others who compare hormonal (e.g., glucocorticoid) changes experienced by monkeys who have lost kin in witnessed predator attacks versus monkeys who have not lost kin but witnessed those same predator attacks. Video, too, is revolutionizing the study of animal emotion; when we film what happens as an animal is dying or dies, we can assess the behaviors by rewatching and coding the tapes, rather than by making snap judgments about what's unfolding quickly in real time."
On the variations of grief across different species:"Animals are individuals. Not all elephants, not all dogs, grieve when a relative or friend dies — some may be curious and want to explore the body, others may be indifferent. I wouldn't want to say 'all animals are capable of grief,' though, because we don't know the scope of animal grief yet. Would I expect amphibians, reptiles, and insects to have the capacity for grieving as birds and mammals do? No, not really. We've yet to fully discover how brain physiology correlates with the expression of emotions like grief in the animal kingdom.
"We humans grieve differently than other animals do: using language, enacting symbolic rituals like funerals, and with an acute awareness of our own and others' mortality. Other animals don't do those things. But many other animals do love. My book is as much about love as it is about grief, because it's from love that the grief emerges."
On how animal grief and emotion change our relationship with animals:"Animals teach us that grief is a natural, if at times profoundly difficult, result of feeling love and joy with another being...What can animal grief teach us about our relationship with other creatures? To me, that's the heart of why animal emotion is incredibly important to study and understand.
"The more we understand that the chimpanzee (or cat or rabbit) confined to a biomedical lab feels his life and his friend's death in the next cage over, and that the dairy cow sorrows over the repeated loss of her calves as they're taken away to slaughter, the more we work effectively towards animal welfare. Each one of us can do something for animals. Maybe you're all about educating children in wildlife conservation, or working to get cats and dogs spay-neutered. Or maybe you decide not to eat animals anymore. Whatever works for you, it all makes a difference."