Why do domestic cats lick each other? The answer is the one you’re thinking about! It is a social exchange that can follow the friendly tail-up greeting. Mutual licking between cats is called allogrooming. Incidentally, the word, as you might imagine, is a combination of ‘allo’ and ‘grooming’. You know what grooming means. The prefix to it, namely ‘allo’ comes from the Greek állos to mean “other”.
As cats spend a lot of their time grooming themselves, which by the way is called “autogrooming”, it is hardly surprising that when two domestic cats sit next to each other, side-by-side, they often lick each other. The reason: mutual bonding between friends.
When they do it, they tend to groom the top of the other cat’s head, under the chin and between the shoulders. These are obviously difficult if not impossible places for a cat to reach when they groom themselves. Cats generally use their wrists to groom difficult spots. They deposit saliva on their wrists and then groom themselves with the wrist. You sometimes see it when they clean around their mouths after they eaten.
There was a time when the experts thought that allogrooming might simply be an accident. What they mean is that when two cats sit side by side and one cat grooms themselves, they might inadvertently start grooming the other cat, not realising that they are no longer grooming themselves.
This explanation seems fanciful to me. Frankly, it seems implausible but we have to be careful not to anthropomorphise cats. However, taking a more enlightened approach to interpreting allogrooming, it is now known that it has a strong social significance just as it does for primates in which it has been linked with pair-bonding and making up after an argument which can happen among family members.
So, we can say with some confidence that in the world of cats allogrooming performs the same function as mutual rubbing i.e. when two cats rub against each other (autorubbing) after a friendly greeting. It is a means to cement a friendly relationship.
In large groups of cats in which there is more than one family most of the allogrooming takes place between relatives of each family.
And there is evidence that allogrooming does in fact reduce conflict between cats. This is seen in what Dr. Bradshaw describes as “artificial colonies” in which rescue organisation volunteers place unrelated cats in the same place to live together (Cat Sense). Under these circumstances there is less aggression than might be expected thanks to allogrooming.
However, allogrooming may also be a form of apology by a more aggressive cat to a more submissive cat. This is because most of the allogrooming is done by aggressive cats. Bradshaw thinks that aggressive cats might lose their temper and then regret it and lick the recipient of their temper tantrum to apologise!
Alternatively, the cat who was the recipient of aggression may allow themselves to be groomed by the aggressor because it is far more pleasant than being attacked and bitten. This interpretation implies that allogrooming is an alternative to aggression and part of a dominance framework in which one cat controls another’s activities.
With respect to the human-to-cat relationship your cat licks you for the reasons given on this page. Your cat relates to you as another cat, probably a surrogate mother or father. Cats often respond to human petting which feels like the allogrooming of another cat. They also engage in allogrooming but this time they lick bare, human skin which might feel a bit unusual until they acclimatise to it via socialisation.