Rattlesnake Ancestor Was Venom Factory

The ancestor of today's rattlesnakes was a serpent to be feared: It had genes to make venoms that would target the blood, the muscle and the nervous system. The eastern diamondback and the western diamondback both have venom that damages muscles, while the Mojave rattlesnake's toxins target the nerves. "This wholesale loss is unusual," study researcher Sean Carroll, a professor of molecular biology and genetics at the University of Wisconsin, Madison, said in a statement.