While it is a common sight in multi-cat households, the behavior known as allogrooming—mutual licking—is more complex than a simple display of affection. Recent studies suggest that when cats groom one another, they are engaging in a sophisticated communication system that can signal friendship, initiate play, or diffuse social tension.
Historically, observations of free-roaming cat colonies led scientists to believe that allogrooming was primarily a tool for social bonding and the creation of a shared group scent. However, a 1998 study involving 25 cats in an indoor-outdoor enclosure challenged this view. Researchers found that aggressive behaviors occurred in approximately 35% of allogrooming sessions, indicating that the act might serve to de-escalate conflicts in confined spaces rather than purely express friendship.
To further investigate, Morgane Van Belle, a cat behavior scientist at Ghent University in Belgium, and her team analyzed video footage of allogrooming from 53 two-cat households. Their findings indicate that the function of grooming changes depending on the context.
In relaxed settings, where cats huddle together and mirror each other’s postures, licking likely strengthens social bonds. Van Belle noted that most grooming is directed toward the ears, an area rich in sensory nerve endings. This stimulation may help the recipient relax, a response similar to the lowered heart rates seen in horses and the release of endorphins in monkeys during social grooming.
The researchers also observed that allogrooming can act as a precursor to play. In some instances, grooming sessions transitioned into friendly wrestling, with cats grappling and tumbling over one another. Conversely, in tense situations, licking was followed by conflict-related behaviors such as ear flattening, pawing, and biting. In these cases, one cat often stood over the other, displaying subtle stress signals like lip-licking or head-shaking. Van Belle’s team proposes that this behavior acts as an “appeasement signal,” calming a potential fight much like subordinate meerkats groom dominant ones. However, because the neck is also a primary target during feline fights, the grooming may simultaneously convey a subtle aggressive threat.
Beyond social signaling, hygiene appears to be another motivator. Allogrooming frequently targets the head and neck, areas that cats find difficult to reach during self-grooming. This mirrors hygienic behaviors in other species, such as ants prioritizing infected colony members and primates focusing on hard-to-reach body parts. However, Van Belle’s study did not measure parasite loads or skin cleanliness, leaving the hygienic benefits in cats unproven.
Dr. Terry Curtis, a veterinary behaviorist, suggests that feral cats, which carry higher flea burdens than house cats, may exhibit different grooming patterns. While she agrees with the hygiene hypothesis, she remains skeptical that researchers can ever definitively pinpoint the exact motivation behind a specific instance of grooming.
“Congratulations, you got a cat. Let the mystery begin,” Curtis said, emphasizing the inherent complexity of feline behavior after 25 years of professional study.
As someone who has studied this for years, I still can’t pinpoint motivations. Cats remain beautifully mysterious and frustratingly complex.
This explains why our cats sometimes go from cuddling to wrestling in seconds. The context is literally everything with these creatures.
Wait, so that lick could actually be a subtle threat? I need to re-evaluate everything my cat does to my other cat right now.
My two cats just finished a session. I always assumed it was pure affection, but the appeasement angle makes so much sense!