Wa Zhi, a chimpanzee in the Taipei Zoo, is seven years and nine months old, equivalent to a human in their adolescence. Keepers looking after primates have observed that chimpanzees and gorillas arrange their unwanted food in different formations. Young individuals, in particular, are more playful in creating one circular form after another using available materials.
Chimpanzees are omnivores that mainly feed on vegetables. They prefer crunchy vegetables such as cabbage and water spinach. And surprisingly, they also enjoy bitter gourds, green peppers, and eggplants, which are often disliked by humans. In fact, they are so fond of eggplants that they have been observed fighting over them. But, they do not enjoy vegetables that are too hard to eat, with astringent taste or short pubescence. Wa Zhi, above all, uses leftover and unpopular vegetables, such as Gynura bicolor, spinach, crown daisy, pumpkin, etc., as playthings or nesting materials.