Clowns are creeping across America, lurking in the woods and generally freaking out the general public.

Over the past few months, “clown sightings” have become a thing, occupying a dark crevice in the popular imagination that was once filled by UFO or Slender Man sightings. And like all viral trends, this one is spreading, with creepy-clown alerts popping up in England, Australia, Canada, and Scotland. Whether they’re teenage pranksters, a movie-marketing ploy, figments of the imagination, or really out to do harm (all possibly true in some cases), the clowns are universally described with one word: creepy.

But why are clowns so creepy? And why are they suddenly popping up all over? Luckily, scientists are giving this some thought, and clown sightings