Scientists believe it is only a matter of time before many transgenes, which scientists borrow from viruses and bacteria and engineer into GM crops, will have spread around the world, incorporating themselves in the DNA of non-GM crops. Potatoes, rice and cotton are sure to be affected; maize already is.
Despite Mexico's 3-year-old moratorium on the use of genetically altered corn, in 2001 scientists detected genetically modified DNA in wild maize in the mountains of the state of Oaxaca. (Oaxaca is the region where maize was domesticated and has the highest diversity of maize in the world.) The wayward genes are from genetically modified corn that is widely grown in Canada and the United States and are now found in remote mountainous regions of Mexico. Up to 70% of wild Mexican maize now carries transgenes that could only have come from genetically engineered crops.