Although science regards them as no more than clever man-made designs, many researchers say there is compelling proof that the origins of these mysterious formations is unexplained.
They began as simple circles laid down in fields of wheat, corn and other crops. Then the formations became more complex, some taking the form of pictograms that seemed to be ciphers for messages of unknown meaning. The phenomenon has continued over the years, and each summer season we are treated to ever-more complex and often beautiful crop circle designs.
The ongoing debate among many crop circle investigators and skeptics has been: Are they manmade or not? While many designs are clearly and admittedly made by people (even veteran crop circle researcher Colin Andrew estimates that up to 80 percent of them are probably manmade), some researchers insist that many formations are not - in fact, cannot be - made by humans.
Skeptical explanations for crop formations have ranged from the ludicrous (one early theory was that they were created by hedgehogs running in circles) to the probable (clever college students). The believers' explanations have been equally as diverse, ranging from the work of extraterrestrials to the idea that the formations are created by the Earth itself as some kind of warning to mankind.
On their side, skeptics have cold rationale and the confessions of such crop circle creators as Doug and Dave in the UK. In 1992, Doug Bower and Dave Chorley, two somewhat elderly retirees, came forward and claimed that they had created hundreds of crop circles over the preceding 15 years using a plank of wood, rope and a baseball cap fitted with a loop of wire to help them walk in a straight line. While their claim is called into serious question by some researchers, it is unquestioned that many crop formations have been "hoaxed" by people using little more than a well-planned design and, yes, planks of wood and rope. Such hoaxers have proved before witnesses and television cameras that they can create large, elaborate designs at night in just a few hours.
But what of the assertion that crop formations are created by some supernatural, extraterrestrial or paranormal force? What is the evidence that compels some researchers to conclude that they almost certainly are not manmade? There are peculiarities to "genuine" crop circles, these researchers say, that cannot be created or hoaxed by humans. Here is some of their "best evidence":