Cleaner fish are sensitive to what their partners can and cannot see

McAuliffe et al. demonstrate that in the context of cooperative cleaning, wild-caught female cleaner wrasse are more likely to cheat when their partners are out of view. This provides evidence that cleaner wrasse possess a building block of theory of mind: sensitivity to what others can and cannot see. Much of human experience is informed by our ability to attribute mental states to others, a capacity known as theory of mind. While evidence for theory of mind in animals to date has largely been restricted to primates and other large-brained species, the use of ecologically-valid competitive contexts hints that ecological pressures for strategic deception may give rise to components of theory of mind abilities in distantly-related taxonomic groups. In line with this hypothesis, we show that cleaner wrasse (Labroides dimidiatus) exhibit theory of mind capacities akin to those observed in primates in the context of their cooperative cleaning mutualism. These results suggest that ecological pressures for strategic deception can drive human-like cognitive abilities even in very distantly related species.

Automated summary

In the context of cooperative cleaning, wild-caught female cleaner wrasse are more likely to cheat when their partners are out of view, demonstrating a certain level of theory of mind ability. These results suggest that ecological pressures may drive the emergence of human-like cognitive abilities in distantly related species.