In a dome-shaped outdoor cage, a dozen chimpanzees are hooting1. The hair on their shoulders sticks straight up. "That’s piloerection," a sign of emotional arousal, says Dr. Dana Hasselschwert, head of vete...In a dome-shaped outdoor cage, a dozen chimpanzees are hooting1. The hair on their shoulders sticks straight up. "That’s piloerection," a sign of emotional arousal, says Dr. Dana Hasselschwert, head of veterinary sciences at展开更多
文摘In a dome-shaped outdoor cage, a dozen chimpanzees are hooting1. The hair on their shoulders sticks straight up. "That’s piloerection," a sign of emotional arousal, says Dr. Dana Hasselschwert, head of veterinary sciences at