Chimp hides rocks.

Before I post the Boston pictures, this article about a chimp who is possibly able to plan for future mood swings is a good read.

"A male chimpanzee in a Swedish zoo planned hundreds of stone-throwing attacks on zoo visitors, according to researchers."

"Crucial to the current study is the fact that Santino, a chimpanzee at the zoo in the city north of Stockholm, collected the stones in a calm state, prior to the zoo opening in the morning. "

"This suggests that Santino was anticipating a future mental state - an ability that has been difficult to definitively prove in animals, according to Mathias Osvath, a cognitive scientist from Lund University in Sweden and author of the new research."

From the BBC.

If that wasn't cool enough for you? Watch elephants problem solve.