A new study has helped scientists prove an old theory that monkeys are capable of mental arithmetic.
A research team led by neurobiologist Margaret Livingstone trained three rhesus macaques to identify symbols representing the numbers zero to 25. They then taught the test subjects how to perform addition.
According to the study, all three monkeys were on average capable of choosing the correct answer “well above” 50 percent of the time. This rules out the possibility of chance.