Humans are mental time travelers: We remember what we thought and felt in the past, and we anticipate what we might be thinking and feeling in the future. So we go food shopping when we are not hungry because we know we will be hungry later, and we put a box of tissues next to us when we start watching a sad movie because we know we might cry.
But do non-human animals do similar things? Researchers are divided on the question, and the evidence is ambiguous. But what might be the closest thing yet to a smoking gun is reported this week in the journal Current Biology. I report on the paper on Science's online news service ScienceNOW (the link is free for four weeks from publication.)
Here's the first paragraph of my story, please read the rest for more details:
In 1997, at the Furuvik Zoo in Gävle, Sweden, a male chimpanzee named Santino began throwing stones at zoo visitors. Although Santino was clearly agitated each time, as evidenced by his forceful stomping around the compound and hair standing on end, the chimp didn't just grab the first thing he saw and launch it. Rather, observations over the past decade have shown that Santino spends the mornings before the zoo opens gathering the stones and organizing them into neat piles as a sort of ammunition store. The chimp's preparation suggests that apes can plan for future mental states--in this case anger--a cognitive talent once thought to be unique to humans.
Photo: Santino and one of his ammunition stores/Mathias Osvath, Current Biology