Guesswork
While the crop circle at Chilbolton looks like an answer to our Arecibo message sent out in 1974, sent back to us with "their" DNA changes and their broadcasting techniques, we are still left wanting to know how such an elaborate hoax could have been perpetuated.
Interestingly enough, many scientists and biologists came up with their own <guesswork.> (Not included, but posted for discussion)