Chimps throwing stones

by Greg Mayer

My local newspaper, along with many other news outlets, had a story this morning about a chimp at a zoo in Sweden who collects and stores rocks that he later uses for throwing at zoo visitors.  The major point of the article was that the chimp made plans for something he was going to do in the future.  This didn’t seem like news to me; I’d heard stories of great apes doing things that seemed to involve at least as much planning.  I asked my friend, Eric Hileman, formerly Director of Animal Welfare and Conservation Education at the Racine Zoo in Racine, Wisconsin, and now a graduate student at the University of Wisconsin-Milwaukee, if he knew of apes planning for the future.  He told me that the Zoo’s orangutans did so.  They would occasionally get hold of some item that a keeper had inadvertently left behind, or that had rolled under a door, such as a pencil or screw.  They would then conceal the item, either in their enclosure or on themselves.  Later, the item would be produced by the orang, and shown to the keeper, but not returned.  If the keeper would offer a snack, then the item would be returned to the keeper in exchange for the food.  Holding on to the item for use in bartering for food in the future, rather than attempting an immediate exchange, seems like planning to me, although these were not planned behavioral experiments that might exclude other interpretations.  He also mentioned a story he’d heard of an orang getting hold of a set of keys, and then secreting them away until the keeper had left, but this is a third or fourth hand story.

Having a temporal sense of events is something that I could not see in my considerations of the moral sense of my cat Peyton. It seems a major advance in cognition, and also in the development of a full (rather than merely rudimentary) moral sense, allowing for retribution, admiration, gratitude, and reciprocity.

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