Monkeys whisper just like humans, researchers have found.

Previously, researchers thought that humans were the only primates that whisper to keep from being overheard. However, tamarin monkeys whisper also, new evidence reveals.

The monkeys were first noticed whispering in New York's Central Park Zoo. Researchers were planning to study the different kinds of calls tamarin monkeys make, as they were already known to be capable of a many different noises.

Other animals also do whisper-gophers and bats, for example; usually to avoid detection by prey. But researchers thought only humans whispered the way humans do-to avoid being overheard by anyone listening or by predators. The tamarin monkey, however, does the exact same thing.

The researchers planned to record the alarm call of these monkeys. However, when a zoo worker walked in, the monkeys didn't raise the alarm call researchers thought they would. Instead, they appeared to fall silent.

Later, when researchers listened to recordings, they realied that the primates weren't silent at all-instead, they'd lowered their voices to "whisper".

The process is known as "low amplitude signaling"-meaning the monkeys were chirping to each other very, very quietly. Resarchers aren't sure exactly what they were chirping about, but researchers think they were most likely reminding each other that the man was threatening-without alerting him that they were talking about him.

The findings indicate that whispering may occur in other species as well...we just haven't listened hard enough yet.

What do you think of the monkeys whispering? Sound off in the comments below!