Vigilance and Group Size in Homo sapiens

While eating, Homo sapiens frequently look up and visually scan their environment. As in many bird and mammal species studied, the frequency of looking up was negatively correlated with group size. Average duration of scanning the environment also correlated negatively with group size. At all group sizes studied (1–5), females spent less time scanning than did males. With increasing group size females reduced their rate of looking up more than did males.