A group of cottontop tamarins were played a variety of music, including Bach, Led Zeppelin and Miles Davis, but they only reacted when heavy metal rock songs by Metallica were played.
Psychology Professor Charles Snowdon teamed up with musician David Teie, who plays cello for the National Symphony Orchestra. They found that 30-second clips composed by Mr Teie on the basis of actual monkey calls provoked the strongest reaction.
Of all the human bands played to the tamarins, Metallica calmed them down.
Mr Teie of the University of Maryland composed using specific features he noticed in the monkey's calls, attempting to convey two opposite emotions – danger and safety.
The monkeys responded accordingly being either anxious or relaxed.
The pair also found monkeys use tone, pitch and other auditory clues to express emotions.
Prof Snowdon, from the University of Wisconsin-Madison, told the Royal Society Journal Biology Letters: "My talking does not necessarily tell you about my emotional state.
"When I add extra elements, change the tone of voice, the rhythm, pitch or speed, that is where the emotional content is contained.
"Monkeys interpret rising and falling tones differently than humans. Oddly, their only response to several samples of human music was a calming response to the heavy-metal band Metallica."
Full story here.