Friendships across Species
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What Animal Bonds Reveal about Consciousness and Emotion
Stories of unlikely animal friendships—an elephant playing with a dog, a gorilla nurturing a kitten, or birds of different species grooming one another—have long fascinated people. Once dismissed as anthropomorphic storytelling, many such interactions are now attracting serious scientific attention.
Behavioral studies increasingly suggest that animals can form stable social relationships not only with members of their own species but sometimes with entirely different species, including natural predators or animals with very different communication systems.
These findings, and hundreds like them, are quietly reshaping how scientists, ethicists, and ordinary animal lovers think about the inner lives of other species. The animal kingdom, it turns out, is full of friendships—some born of survival, others of something harder to name.
Researchers are increasingly interested in what these interactions might reveal about the emotional and cognitive lives of animals. Laboratory and field experiments show that many species—ranging from chimpanzees and elephants to parrots and wolves—can cooperate toward shared goals and may understand when a partner, even of another species, is needed for success. Meanwhile, studies of empathy in animals, from rodents freeing trapped companions to hens showing stress when their chicks suffer, suggest that emotional responsiveness is not uniquely human.
“To endow animals with human emotions has long been a scientific taboo. But if we do not, we risk missing something fundamental, about both animals and us.”
“To endow animals with human emotions has long been a scientific taboo,” said the late primatologist and ethologist Frans de Waal. “But if we do not, we risk missing something fundamental, about both animals and us.”
If animals are capable of forming friendships across species boundaries, the implications are profound. Such relationships challenge traditional assumptions that animal behavior is driven solely by instinct or self-interest. Instead, they may point toward more complex forms of social awareness, emotional sensitivity, and perhaps even rudimentary moral behavior.
Two Kinds of Connection
Scientists generally describe interspecies relationships in two broad categories. The first is mutualism: ecological partnerships where both animals gain a clear, practical benefit. The second is something warmer and harder to quantify—genuine social bonds, the kind that look, at least from a distance, a lot like friendship.
Author and lecturer Jenn Savedge compiled a list of 10 examples of where animals of different species cooperated in the wild. Her examples of mutualism include coyotes and badgers hunting ground squirrels together, each compensating for what the other lacks—the badger digs, the coyote waits above ground. Pistol shrimp, nearly blind, share burrows with gobies, who have excellent eyesight; the goby keeps watch while the shrimp tidies the home. Zebras and ostriches travel in loose companionship; the zebra’s sharp eyes are paired with the ostrich’s keen sense of smell, and each animal is safer because of the other’s presence.
These are ancient arrangements, shaped by millions of years of pressure and practicality.
Smaller animals, like cleaner fish, cattle egrets, and red-billed oxpeckers, remove parasites from larger “clients” like sharks, water buffaloes, and rhinos. The smaller animal gets a meal, and the larger one gets pest control.
But then there are the other kinds of bonds, the ones that lack a clear survival necessity. They are more frequently documented in captivity or human-controlled environments (like zoos) rather than the wild. Cooperative bonds are almost exclusively found among social species with deep-seated instincts for group interaction. Success often depends on whether different species can interpret each other’s alarm calls or body language.
There are numerous recorded cases of one species adopting an orphan from another, such as chimpanzees raising tiger cubs, a fawn curled up beside a golden retriever, or a capuchin monkey that has, seemingly against all biological logic, adopted a marmoset as family.
What Cross-Species Friendship Looks Like
Interspecies social bonds are most frequently observed among mammals, particularly domesticated animals and primates, which often form companionship, play, or grooming relationships. Frequent pairs include dogs and cats, dogs and other species (like deer or pigs), horses and goats, and young, orphaned animals that form surrogate family bonds. Empathy may be at the root of these pairings. One animal may take another under its wing, so to speak, “to relieve its pain, hunger, or loneliness,” said Jenny Holland, who wrote the 2011 book Unlikely Friendships, in an interview with National Geographic. “Mammals have the same brain structures, the same system, related to emotion that we have, so why not?" she said.
“Friendships” in the wild are rare and usually limited to specific scenarios, unlike the more widespread emotional bonds observed in captive environments.
Captivity, interestingly, tends to intensify these cross-species bonds. When animals are removed from their natural social groups and placed alongside unfamiliar species, they often reach across the species barrier to form connection. A cheetah cub raised without feline companionship may bond deeply with a dog. The instinct for companionship, it seems, is robust enough to override even the deepest biological instincts.
How do scientists tell the difference between animals that happen to be near each other and animals that actually care about each other? The answer lies in a handful of telling behaviors.
Key indicators include mutual grooming (licking/cleaning), social play, sleeping in close proximity, shared resting, and protective gestures. These behaviors are largely driven by a mutual need for companionship, reduced stress, and the development of a unique, nonverbal communication system between the species.
Examples are cats “bunting” and dogs “playing bows“ to signal that what follows is fun, not threat. They show up in protectiveness, in excited greetings after separation, and most tellingly, in what researchers call active maintenance—an animal seeking another animal out simply because the other is nearby.
Underlying all of this is what scientists increasingly call social intelligence: the ability to read, interpret, and respond to the emotional states of another being—even one that communicates in an entirely different language of sound and scent and movement.
Dogs do this with remarkable fluency, picking up on human emotional cues with a sensitivity that still surprises researchers. Wild fish have been observed becoming bolder in the presence of domesticated ones. Vervet monkeys give specific alarm calls for specific predators, and other species nearby—birds, antelopes—have learned to understand and act on them.
Using computational tools, scientists can track social interactions over time to differentiate cohesive, long-term bonds (e.g., in the plains zebra) from transient, accidental, or merely gregarious interactions.
In essence, if two animals are always together and they groom each other, it is likely a genuine bond. If they are only together at a specific feeding spot, it is coincidental proximity or mutual benefit.
The Question of Feelings
All of this points toward a territory scientists once entered reluctantly: the question of whether animals have feelings. The evidence now suggests that many do, and with a sophistication that challenges older assumptions about the uniqueness of human emotion. For example, “a growing body of scientific evidence supports the idea that nonhuman animals are aware of death, can experience grief, and will sometimes mourn for or ritualize their dead,” says bioethicist Jessica Pierce.
Neuroscience experiments have identified that the same neural circuitry—spanning the amygdala and the prefrontal cortex—that activates in an animal experiencing pain also activates in the animal watching its companion suffer.
Research at the University of Chicago found that free rats will learn to open a restrictive tube to release a trapped companion. The free rats also tended to the trapped rats first, even before accessing proffered chocolate, demonstrating what appeared to be empathy-driven behavior.
Prairie voles groom and comfort distressed mates, driven by oxytocin, the same bonding hormone found in humans. Observations in complex social animals like primates, elephants, and dolphins show them displaying comforting behaviors toward stressed individuals and acting in ways suggesting grief for the dead, as described in this BBC Earth YouTube video.
In primates and other social animals, scientists have also documented empathy-like behaviors, including comforting distressed companions, sharing resources, or helping injured individuals. A recent long-term study of chimpanzees even found cases in which individuals treated the wounds of unrelated companions, raising intriguing questions about the origins of caregiving and compassion.
How Do Animals Communicate across Species Boundaries?
Social intelligence allows animals to interpret nonverbal cues and emotional states across species, fostering empathy and bridging communication gaps to form deep emotional bonds. Most interspecies communication relies on “eavesdropping” on universal auditory, visual, and chemical signals that convey vital information regarding predators, prey, or territory. These shared systems include specific alarm calls, such as those used by vervet monkeys, as well as tactile cues and scent marking to define boundaries and reduce conflict. Collectively, these methods enable social animals to navigate complex multispecies environments and build relationships through mutual understanding.
Cooperative behaviors in animals strongly suggest the presence of advanced cognitive abilities, including rudimentary emotional awareness, social intelligence, and in some cases, shared intentionality. These behaviors indicate that animals are not merely driven by instinct but can possess a “theory of mind” that allows them to understand and respond to the goals, intentions, and emotional states of others.
Cooperative behaviors, such as the boundary patrols of chimpanzees or collaborative hunting, suggest that animals can plan, share intentions, and understand the need to work together to achieve a mutual goal.
New research, particularly in cognitive science and neuroscience, is reshaping ethical debates by objectively validating animal sentience, emotions, and consciousness.
Social species, which are more likely to cooperate, often show higher levels of self-awareness (such as mirror self-recognition in dolphins) and can distinguish between consistent cooperators and noncooperators.
Some animals, such as primates, can remember past interactions and selectively cooperate with partners who have helped them before, suggesting memory-driven social relationships.
Studies in mice show that cooperation relies on the anterior cingulate cortex of the brain, which acts as a hub for representing the partner’s position and making coordinated social decisions.
Why It Matters
New research, particularly in cognitive science and neuroscience, is reshaping ethical debates by objectively validating animal sentience, emotions, and consciousness, shifting the focus from whether animals suffer to how they experience suffering. These findings challenge existing regulatory frameworks, strengthening arguments for reducing animal experimentation and making it harder to justify practices where human benefit is not heavily proven to outweigh animal suffering.
As science demonstrates greater cognitive complexity, the debate is evolving from utilitarian arguments (is the experiment worth the cost?) toward rights-based ethical frameworks that prioritize the inherent rights of animals, particularly for higher-order mammals.
That shift matters. It indicates that humans are not alone in the capacity for connection. We share this Earth with creatures who, in their own ways, also choose loyalty, also seek comfort, also grieve.
*Dirk Anthonis is a freelance writer and former New York City Tribune editor who lives in Kansas City, Kansas.