One of our readers wrote in with this question: Why is it that whenever I see someone looking at something, like someone gazing up at the sky, I look there too? Is it just me, or do we all do this?
Here's the answer:
We all do this! It's what scientists call gaze-following. We're all prone to follow another person's gaze even if we're not sure what they're looking at, or why.
British researchers think it dates back to our primitive primate ancestors, who may have evolved the behavior as a way to locate food. When the British scientists studied gaze-following in lemurs, which are very primitive primates, they found that lemurs do in fact use gaze-following as a strategy to locate areas likely to contain food. When a lemur sees one or more of its fellows looking in a particular direction, it will turn its attention that way too. At some point, the lemur is likely to search that area for hidden food.
Gaze-following could also be a way of sensing danger and staying away from a certain place. In any case, our human tendency to gaze-follow could have ancient origins. We no longer follow gazes for foraging purposes. But it's still useful as a way of being alerted to something interesting, or menacing, in the vicinity.