Individual recognition is associated with holistic face processing in paper wasps in a species-specific way.

Most recognition is based on identifying features, but specialization for face recognition in primates relies on a different mechanism, termed 'holistic processing' where facial features are bound together into a gestalt which is more than the sum of its parts. Here, we test whether individual face recognition in paper wasps also involved holistic processing using a modification of the classic part-whole test in two related paper wasp species: , which use facial patterns to individually identify conspecifics, and , which lacks individual recognition. We show that use holistic processing to discriminate between face images but not face images. By contrast, do not rely on holistic processing to discriminate between conspecific or heterospecific face images. Therefore, wasps have evolved holistic face processing, but this ability is highly specific and shaped by species-specific and stimulus-specific selective pressures. Convergence towards holistic face processing in distant taxa (primates, wasps) as well as divergence among closely related taxa with different recognition behaviour (, ) suggests that holistic processing may be a universal adaptive strategy to facilitate expertise in face recognition.