Tucked into the semi-wilderness a few miles north of this Central Texas town, within spitting distance of a federal prison, Nahja, a 25-year old chimpanzee at the Keeling Center for Comparative Medicine and Research, wraps a handful of woolly nesting material around her head into something that resembles a shawl. When a handler calls her name, Nahja stretches out her massive hands and catches an orange - this morning's treat - tossed from the observation balcony overlooking the 75-foot wide corral where she and the rest of her social group live.