A common parasite found in cats may be affecting human behavior on a mass scale, according to a scientist based at the University of California, Santa Barbara. While little is known about the causes of cultural change, and biological explanations often stimulate social and scientific debate, a new study by the U.S. Geological Survey published in the August 2 issue of the Proceedings of the Royal Society, Biology, indicates that behavioral manipulation of a common brain parasite may be among factors that play a role. "In populations where this parasite is very common, mass personality modification could result in cultural...