It appears the ability to strike is not just limited to humans, in a study conducted by scientists, monkeys refused to perform tasks when they felt unfairly treated. A group of monkeys were given a task and presented with a reward for completing it. Some of the monkeys were given a better reward than others. For example one monkey would receive a piece of cucumber whilst the other might receive a grape. When the other monkeys noticed that their partners received better rewards for the same task, they refused to perform the task again and often became upset refusing to eat the cucumber and instead throwing it at the human researchers.