"After a visitor group had left the compound area, Santino went inside the enclosure and brought a good-sized heap of hay that he placed near the visitor's section, and immediately after that he put stones under it. He also appeared to have placed projectiles behind, just before he went in after the hay. After this, he sat down beside the hay and waited. When the visitors came back, he waited until they were close by and, without any preceding display, he threw stones at the crowd. What makes this a bit special is that he actually had not experienced before what he seemed to anticipate. He, in a sense, [...]

Okay, I guess we have to go here. How do monkeys make sex tools? The New York Times talks to University of Cambridge primatologist William C. McGrew, who notes that male chimpanzees (who are, I know, NOT monkeys, but whatever) take dry, dead leaves and begin ripping them apart to attract attention. There is indeed more.

"I favour the hypothesis that stick carrying is practice for the adult role of motherhood. perhaps similar to functions of other kinds of play, being practice for adult roles … It was striking that this behaviour was seen in some adult females, but never after they became mothers." —Zoologists Sonya Kahlenberg of Bates College, who, with her colleague Richard Wrangham of Harvard University, observed juvenile chimps in Uganda's Kibale National Park playing with sticks "like children play with dolls, cradling them and even making nests for them to sleep in at night." I wish I had some juvenile chimps in my family. They seem very easy to [...]