A study recently published in Proceedings of the National Academy of Sciences reports a surprising finding: Jumping spiders twitch during sleep in a way that resembles what cats, dogs, and other mammals do during rapid eye movement sleep. The study’s German researchers noticed leg jerks happening at the same time as the eye movements, suggesting that these spiders dream. Similar evidence has been recorded for two other invertebrates — octopuses and cuttlefish — as well as for birds and fish.
Do these animals dream the way we humans do? If only they could tell us. The evidence, though, is increasingly persuasive that they do, especially if we bear in mind Darwin’s dictum that differences between species are a matter of degree, not kind.
As argued by David Peña-Guzmán in his recent book, “When Animals Dream,” dreaming indicates that an animal is sentient — a unique individual who experiences life and processes it via thoughts and feelings. Put another way: Animals don’t just have biologies, they have biographies.
The implications, we believe, are compelling. If a creature can feel and express feeling — if it can emote, in other words — then it is entirely possible that he or she is a spiritual being. While this may sound startling, a closer look at what animals do lends credence to the idea.
Many animals demonstrate concern for other animals, sometimes paying a cost or taking a risk to rescue another. Upon spotting an approaching predator, prairie dogs, chickens, and mongooses, for example, will utter alarm calls, drawing attention to themselves while alerting the rest of the colony. A rat will come to the aid of a fellow rat in distress, even when it means having to share a treasured piece of chocolate. Acts like these suggest expressions of sympathy: the inclination to act on the feeling of empathy.
Humpback whales and orcas demonstrate friendship and loneliness, even gratitude. Elephants give every appearance of what we would term joy and sorrow, even mourning their dead and experiencing something akin to post-traumatic stress disorder. Parrots can become depressed, pigs terrified, baboons sad, and starlings pessimistic. Octopuses and crows show marked preferences for certain people. Fish seek out gentle caresses to relieve stress. Rats appear to enjoy being tickled. Chimps sometimes linger to watch a beautiful sunset, appearing transfixed, as if in wonder. And a growing number of animals — including dolphins, elephants, great apes, magpies, reef fish, maybe even ants — appear to be self-aware, as demonstrated by their response to seeing their reflection in a mirror.
All of this indicates sentience and a felt connection to what is happening outside themselves.
Such fellow feeling, we posit, is at the root of spirituality. As neuroscientist Antonio Damasio has observed, “Feelings form the basis for what humans have described for millennia as the . . . soul or spirit.” This is reflected in our very language. A “soulless” person or corporation displays an utter lack of empathy. An athlete who motivates his or her fellow players is known as the team’s “heart and soul.” We confide to our beloved that we want them “body and soul.” In each case, soul is associated with deep feeling.
The stronger the capability a given species has for fellow feeling, the more likely it is that members of that species have perceptions that we would recognize as spiritual. This goes beyond individual attributes such as memory, a sense of time, an ability to feel pain, the capacity to dream, or even a subjective ”I” — it is the culmination of all of them. The ability to emote is, in our estimation, a nascent form of soul. This is not intended to have any religious connotation — we are not suggesting even a spider’s jump in that direction. It is merely a biophilic view that many sorts of creatures share a connected sentience on this increasingly small, restive, and fragile planet.
Why small? Because wild creatures and their living spaces are disappearing. Consider that today, the world’s nonplant biomass of wild terrestrial vertebrates — all the land-inhabiting mammals, birds, reptiles, and amphibians — makes up a meager 4 percent of the total biomass of everything on land. The remainder is made up of humans, 36 percent, and the animals we raise to eat, 60 percent. Under the water, fish populations are about half of what they were 50 years ago. Insects, which make up some 80 percent of all animal species on Earth, show comparable declines.
Make no mistake: We are utterly dependent on diverse, functioning ecosystems for our own survival. Not only does recognizing and respecting nature’s other souls reflect the fact that we share an elemental emotional bond, but doing so is an act of self-preservation.
Jonathan Balcombe is a biologist and the author of five popular science books, including the New York Times best-seller “What a Fish Knows.” He is a co-founder of the journal Animal Sentience. Michael Jawer is the author of three books focused on emotion and spirituality. His articles have appeared in Aeon, Nautilus, and Scientific American.