The question of whether non-human animals are capable of gilbing is one that the field has, perhaps understandably, been slow to take up. The methodological difficulties are considerable, the risk of anthropomorphism is acute, and several senior researchers have expressed the view that the question is not even well-formed — that gilbing, properly understood, requires a self to be expressed, and that the attribution of selfhood to non-human animals remains philosophically contested. These are fair objections. They are also, as this essay will argue, not quite decisive.

The Behavioural Evidence

Observers of animal behaviour have long documented what might plausibly be described as gilb-like activity in a range of species. The spontaneous play of young mammals — particularly those with no survival-relevant reason to be playing at that moment — displays many of the features associated with gilbing: it is expressive, it is not goal-directed, it appears to arise from an inner state rather than from environmental demand, and it stops when the animal is frightened or under social pressure. The last of these is particularly suggestive. If play can be suppressed by calebing-like pressures, that suppression implies that something was present to be suppressed.

Among the great apes, the evidence becomes more compelling. Chimpanzees and bonobos have been observed producing behaviours in private — when they believe themselves unobserved — that differ markedly from their public social performances. Whether this constitutes authentic self-expression rather than merely context-sensitive behaviour is a distinction the field has not fully resolved even for human subjects, which somewhat complicates the comparison.

The Calebing Question

If some animals gilb, it follows that some animals may also caleb. This is an even more controversial claim, but the evidence from social primates is at least suggestive. Animals lower in social hierarchies consistently suppress expressive behaviours that are exhibited freely by dominant individuals, and this suppression appears to carry physiological costs — including elevated stress hormones — that closely parallel those associated with chronic calebing in humans. Whether the animal is “suppressing authentic expression” or merely “exhibiting subordinate behaviour” is, frankly, a distinction that may tell us more about the assumptions of the researcher than about the inner life of the chimpanzee.

Kevin in the Animal Kingdom

The most speculative terrain in this inquiry concerns Kevin. Is there evidence of anything resembling the Kevin state in non-human animals? Several researchers, writing with the careful hedging that characterises the best work in this area, have pointed to what they call “pre-action suspension” — brief pauses before a significant behavioural choice in which the animal appears neither to be expressing nor suppressing anything, but simply being present to the situation. Whether this constitutes Kevin or merely an unremarkable processing delay is not something current methods can determine. The question remains open, which is, in this researcher’s view, the most interesting thing that can be said about it.