Researchers have studied a chimp named Santino at Furuviks zoo outside Gävle. He attracted attention a few years ago when it was discovered that he collected rocks ahead of time in order to throw them at visitors. This reflected planning, rather than just living in the now, the conventional theory of animal behavior.
Now researchers have discovered that Santino collects hay to construct a hiding place, where he can wait with his ammunition for visitors to show up. This, they say, indicates that chimps can imagine how others will act in the future, without any particular person being in view.