'Grass-in-the-ear' technique sets new trend in chimp etiquette

Jul 03, 2014
A chimp showing "grass-in-the-ear" behavior. Credit: Edwin van Leeuwen

Chimpanzees are copycats and, in the process, they form new traditions that are often particular to only one specific group of these primates. Such are the findings of an international group of scientists, who waded through over 700 hours of video footage to understand how it came about that one chimpanzee stuck a piece of grass in her ear and started a new trend, and others soon followed suit. The findings of the study, led by Edwin van Leeuwen of the Max Planck Institute for Psycholinguistics in The Netherlands, are published in Springer's journal Animal Cognition.

In 2010, van Leeuwen first noticed how a female chimp named Julie repeatedly put a stiff, strawlike blade of grass for no apparent reason in one or both of her ears. She left it there even when she was grooming, playing or resting in Zambia's Chimfunshi Wildlife Orphanage Trust sanctuary. On subsequent visits, van Leeuwen saw that other in her group had started to do the same.

This aroused his interest to find out if they copied what Julie did by watching and learning from her through so-called social learning. The research team, including Zambians who monitor the chimpanzees daily, collected and analyzed 740 hours of footage that had been shot during the course of a year of 94 chimpanzees living in four different social groups in the sanctuary. Only two of these groups could see one another.

The research team found that only one of the four groups regularly performed this so-called "grass-in-the-ear" behavior. In one other group one chimpanzee once did the same. Eight of the twelve chimpanzees in Julie's group repeatedly did so. The first to copy her was her son, Jack, followed by Kathy, Miracle and Val with whom she regularly interacted. Generally at least two of the chimps put grass in their ear at the same time. Interestingly, the chimpanzees Kathy and Val kept up the custom even after Julie, the original inventor of this behavior, died.

The observations show that there's nothing random about individual chimpanzees sticking grass into their ears. They spontaneously copied the arbitrary behavior from a group member. Chimpanzees have a tendency to learn from one another – clearly a case of "monkey see, monkey do" in fact. Van Leeuwen suggests that those animals that find a specific behavior somehow rewarding will continue to do so on their own, even if the chimpanzee they have learned it from is no longer around.

"This reflects chimpanzees' proclivity to actively investigate and learn from group members' behaviors in order to obtain biologically relevant information," says van Leeuwen. "The fact that these behaviors can be arbitrary and outlast the originator speaks to the cultural potential of chimpanzees."

Explore further: Chimpanzees flexibly adjust their behavior to maximize payoffs, not to conform to majorities

More information: Van Leeuwen, E.J.C. et al (2014). A group-specific arbitrary tradition in chimpanzees (Pan troglodytes), Animal Cognition. DOI: 10.1007/s10071-014-0766-8

add to favorites email to friend print save as pdf

Related Stories

Mother chimps crucial for offspring's social skills

Sep 06, 2013

Orphaned chimpanzees are less socially competent than chimpanzees who were reared by their mother. Researchers from the Max Planck Institute for Psycholinguistics in Nijmegen, The Netherlands, observed that ...

Chimpanzees create social traditions

Aug 29, 2012

(Phys.org)—Researchers have revealed that chimpanzees are not only capable of learning from one another, but also use this social information to form and maintain local traditions. A research collaboration ...

Chimpanzees respond to infant death nearly same as humans

Feb 03, 2011

(PhysOrg.com) -- For the first time, researchers of the Max Planck Institute for Psycholinguistics in the Netherlands report in detail how a chimpanzee mother responds to the death of her infant. The chimpanzee ...

Recommended for you

Male sex organ distinguishes 30 millipede species

15 hours ago

The unique shapes of male sex organs have helped describe thirty new millipede species from the Great Western Woodlands in the Goldfields, the largest area of relatively undisturbed Mediterranean climate ...

Dogs hear our words and how we say them

Nov 26, 2014

When people hear another person talking to them, they respond not only to what is being said—those consonants and vowels strung together into words and sentences—but also to other features of that speech—the ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

supamark23
5 / 5 (1) Jul 03, 2014
So, monkey see monkey do has been scientifically proven? Sweet!
antigoracle
1 / 5 (1) Jul 06, 2014
Monkey see monkey do is also what drives the AGW Cult, well that and general stupidity.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.