(Semi-serious Question) Other than people, what causes crop circles? in Science & Spaceflight Posted January 10, 2015 One with a six-seven digit budget could probably build a more or less autonomous robot that generates a random pattern and then imprints into the crop. But that would ultimately count as "caused by people" anyway.Extraterrestrials, as the question tries to lead us ? No, unless they have the same motivation as human pranksters, and no interest in actual communication. But then, occam's razor. Extraterrestrials with psychology that causes them to consider "paint geometric shapes over the first suitable big surface" as their first choice of communication ? Maybe, but by finding suitable crop fields and waiting with painting until no witness is around they would demonstrate they got a lot of knowledge about humans. Enough knowledge to realize that human psychology is different and this is not the best way to communicate with us. And someone building interstellar spaceships is bound to be smart enough to figure out.