STOCKHOLM, Sweden -- A chimpanzee who calmly collected a stash of rocks and then hurled them at zoo visitors in fits of rage has shown the animals can plan ahead just like humans, a study said Monday.

PETA attorney Brittany Peet shares how support for the Captive Primate Safety Act can change the lives of animals like Tonka the chimpanzee Brittany Peet, general counsel for captive animal law ...

Among nonhuman mammals, hostility between rival groups is quite widespread, but it rarely leads to death. The frequent fighting between males is most often ­limited to intimidation be­hav­ior. While ...