You've landed a small role in a low-budget horror movie. To get ready, you need to practice your reaction shot—you know, that look you'll get when your boss peels off his face to reveal the slime-oozing alien he really is. So, look in the mirror and give us some terror. If you're doing it right, your eyes are wide open and your eyebrows are raised. But why is that? I mean, how come people, when they're scared, all make a similar face? Darwin thought there was a reason, that our expressions evolved because they offer some benefit. And scientists from Ontario think Darwin was right. They asked volunteers to try to look frightened and then they measured the physiological effects. They found that making a fraidy face allows people to see farther, locate targets faster and take in more air when they breathe. The findings appear in the current online issue of Nature Neuroscience. Those reactions make sense, because if you see something startling or out of the ordinary, you can use your fear-enhanced vision to assess the situation.