Our happy hour fact to amaze your drinking buddies with.

Monkeys seem to enjoy the sounds of hard rock.

Researchers played a group of cotton-top tamarin monkeys a variety of musical types, such as jazz and classical, and found that they only reacted when they heard the loud, fast-paced sounds of a band like Metallica. Instead of banging their heads, however, the heavy metal made the simians appear calm and content.

While the researchers were also able to coax reactions from the cotton-tops when they played them a special composition of cello music and monkey calls, in some cases this would just agitate the apes.

This discovery actually raises our assessment of the typical heavy metal fan's level of sophistication.