Figure 2.

Phylogeny of vertebrate gaze following. Though the most robust evidence for gaze following has emerged from primates, other mammals and birds have also been found to follow gaze. Evidence comes primarily from three groups: domestic mammals including goats and dogs, captive cetaceans including dolphins and seals, and birds including corvids and ibises. Better understanding of the evolution of gaze behavior will require more comparative studies, with a particular eye toward distinguishing both the sophistication and species-specificity of gaze cue responses.