Figure 2.

Significant positive relationship between expert ratings of primate-typical use of staring as a threat signal and the more stratified or affiliative attributes of their social relationships (hierarchical versus more egalitarian). On the x-axis, a 0 (completely hierarchical) to 100 (completely egalitarian) scale of primate social structure. On the y-axis, a 0 (no use) to 100 (exclusive use) scale of primate use of staring as a threat signal. This figure is generated from a data set consisting of 55 data points. For the sake of interpretability, these 55 data points have been collapsed into the shown 19 data points. Each point represents a specific grouping of primates as indicated by their labeling.