August 5, 2011
Mandrills Cover Their Eyes To Show They Want To Be Left Alone
Experts say that monkeys learn to cover their eyes when they want to be left alone.
Zookeepers at Colchester Zoo first noticed Milly, a 15-year-old mandrill, covering her eyes in 1999, when she was three.
Staff thought at first she had poor eyesight or was just trying to shade her eyes from the sun.
It was not until evolutionary biologist Mark Laidre of the University of California, Berkeley decided to take interest when the truth was realized about Milly.
He spent 100 hours studying the mandrills community at the zoo in 2007 and 2008 and noticed the significance of the gesture.
"I'd never seen this before "“ I knew it was very interesting," he wrote in the Scientific American magazine.
"By covering their eyes with their hands, individuals possibly conveyed to others that they wanted to be left alone and this message may have been respected as a 'do not disturb' sign."
A monkey's signal involves placing the hands loosely over the eyes while keeping watch through fingers parted.
According to the research, those who rank lower in the social order use the technique to avoid attacks from more dominant group members.
The discovery appears to be unique to Colchester Zoo, which hosts a community of 25 mandrills.
Curator Sarah Forsyth said in the magazine: "We believe Milly made up the signal and over the past five years some of the younger mandrills have picked it up. We're not sure why she started doing it but it could be as simple as "ËI can't see them, so they can't see me'. It really does show you how intelligent mandrills are."
Mandrills thrive in Africa, mainly in the rainforests of Cameroon, Gabon, Equatorial Guinea and Congo.
The monkeys live for around 20 years and adults typically grow to about 3-feet and weigh around 77-pounds.
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