A monkey’s intelligence is difficult to measure since intelligence is typically assessed by evaluating a species’ ability to solve complex problems. Generally speaking, monkeys are considered to be one of the smartest animal species outside of humans.
In fact, some studies have found some species of primates to be smarter than some species of birds and mammals. Monkeys are capable of demonstrating impressive problem-solving skills, quickly learning commands and cues from their trainers, and even remembering learned behaviors after long periods of time.