Panpan, the world's oldest male panda, is seen at the China Conservation and Research Center in Dujiangyan, Southwest China's Sichuan province, on July 15, 2016. Panpan is 31 years old -- the equivalent of 93 human years. Born in the wilderness in Baoxing county, Sichuan province, he fathered around a quarter of all the pandas living in captivity in the world today and therefore was dubbed "hero dad". [Photo/Xinhua]