A rock-throwing chimp at Sweden's Furuvik Zoo proves that nonhuman primates can plan for the future. For the past several years, Santino has put on a show of dominance every day at around 11 A.M. by yelling and running around, which is typical of male chimps. But he would occasionally lob rocks at zoo visitors. (Fortunately, his aim is terrible, and no one has been seriously hurt.) Workers found that earlier in the morning he would calmly fish his ammunition out of the moat around his habitat and chip away at concrete rocks on his island to form dessert-plate-size disks. Santino would then pile up his weapons. This observation, described in the March 10 Current Biology, confirms lab experiments showing that our fellow apes can prepare for upcoming events.