In 1991, self-professed pranksters Doug Bower and Dave Chorley stated that they had started the phenomenon in 1978 by making actual circles on crops with the use of simple tools. However, crop patterns did not only persist but became astonishingly complex. Some even came to resemble stereotypical extraterrestrials as portrayed by science fiction movies, fractals and archaeological, religious or mythological symbols, thus leading to speculation and passionate debate. Among others, paranormal enthusiasts, ufologists and anomalistic investigators have offered arousing yet hypothetical explanations that have been criticized as pseudoscientific by skeptical groups like the Committee for Skeptical Inquiry.
Most of the observed patterns have revealed as products of deception, artistic expression and business or tourist interests. Some cases have been examined by a few researches via the scientific method.