Of all the activities and behaviors that are recognized as being uniquely “cat-like”, perhaps the most perplexing is kneading. Although many cats knead, and animal behaviorists can explain many behaviors of the typical cat, finding an explanation for kneading behavior has thus far eluded those who have attempted to explain it. Kneading consists of the cat alternatively pushing on a surface—always soft or pliable—with their left and right paws. Typically, the cat extends its claws whilst pushing, effectively gripping the surface, and then retracts the claws when the paw is pulled away and traded for the other paw. Some cats keep their claws retracted throughout, but most do not. This can lead to a painful situation for cat owners whose pets decide to knead in their laps, as claws that are sharp are easily capable of pushing through clothes.

Kneading seems to be instinctive. It is not a learned behavior, but rather hardwired into the cat brain—cats will knead even when they have never observed another cat doing so. Therefore, most who have attempted to explain it believe that it must serve some adaptive purpose. Perhaps the most enduring explanation for kneading behavior is related to the idea that it is part of the milk stimulation reflex in kittens. As they attempt to latch onto their mother’s teat, newborn kittens will knead the belly of the mother. This stimulation is thought to accelerate the milk production and letdown reflex, increasing the amount of milk for the kitten. For a long time, behaviorists theorized that adult cats that knead are those who have been separated at too early an age from their mothers, and therefore the kitten behavior persists into adulthood. A more plausible explanation would seem to be that the behavior, if related to suckling, might simply be comforting in the same way that petting a cat’s head may replicate the sensation of a mother licking her kitten’s head.

Another explanation has it that kneading is related to bedding down. In this scenario, the behavior serves the same purpose as that of the dog who will turn in several circles before laying down: to pat down grass or other plant material to form a suitable natural mattress. The fact that many cats knead shortly before going to sleep lends some credence to this explanation.

A final potential explanation for kneading has to do with territoriality. Cats have scent glands in their paws, and kneading may release the scent onto the surface that is being kneaded. In this scenario, kneading an object is akin to claiming it as the cat’s property. This is similar to the behavior of a cat which rubs its cheeks and flanks on the legs of its owner; many pet owners attribute this act to affection, and they may be surprised to learn that in actuality, the rubbing is an indication that the cat feels the owner belongs to it. This would explain why cats so often knead when sitting on their owners, and also why female cats increase kneading behavior when they go into heat (a time when other signs of territoriality also increase). Whatever the explanation for kneading, many pet owners find the behavior irritating, especially when it is their lap being kneaded, and so kneading may serve as a good justification for keeping the cat’s claws trimmed.