As reported by National Geographic, intelligence in chimpanzees appears to be strongly heritable, according to research led by William Hopkins, a primatologist at the Yerkes National Primate Research Center in Atlanta, Georgia, who examined both genetic and environmental factors for a group of related chimpanzees with varying measured intelligence: To find out how much of that variability is due to genetics, Hopkins and his team assessed the cognitive abilities of 99 captive chimpanzees. They used a battery of 13 tests measuring various manifestations of intelligence, such as how the animals dealt with the physical world, reacted to sound, and used tools. The group of chimps tested had an expansive family tree, ranging from full siblings to fourth and fifth cousins. This allowed the researchers to calculate how well scores on cognitive traits aligned with genetic relatedness. Two categories of tasks were significantly heritable: those related to spatial cognition, such as learning physical locations, and those that required social cognition, such as grabbing a person's attention. Some chimps are quite clever, making kissing sounds or clapping their hands to draw an experimenter's attention, Hopkins said. "This one is a real measure of intelligence and innovative behavior."