Don: Time to go again to the A Moment of Science mailbag. A listener writers:

     Dear Yaël and Don:
     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?

Yaël: Great question! And the answer is that what scientists call gaze-following is pretty      much a universal human trait. We're all prone to follow another person's gaze even if      we're not sure what they're looking at, or why.

D: Right. But why do we gaze-follow? 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. And at some      point the lemur is likely to search that area for hidden food.

Y: Of course, gaze-following could also be a way of sensing danger and staying away      from a certain place. In any case, the point is that 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.  

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