Question: Why do you use monkeys

Lewis Dean answered on 8 Mar 2014:

We use apes and monkeys because they are our closest living relatives. By looking at how they solve puzzles and comparing it to how children (and adults) solve puzzles, we can see what is unique about humans.

However, there are lots of scientists doing similar research with lots of other species. Dolphins, crows and dogs are all really intelligent in different ways and can teach us about how intelligence has evolved.