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Interviewee: Terry Ord, University of California-Davis
Lizards Talk Tough
You may have seen robotic fish, robotic dogs, and even robotic roaches.
But you’ve probably never seen a robotic lizard that does four-legged pushups. Its creator is evolutionary ecologist Terry Ord. Ord’s interest in lizards and other animals began as a child growing up in Australia, where his family spent weekends and holidays on their property in Australia’s bush country.
“Amongst the rock outcrops around the house, lizards defended territories with elaborate performances of pushups and other displays,” Ord recalls. “The spectacle evidentially had a lasting impression because I would devote my PhD research to deciphering what exactly it was they were saying to each other.”
As a researcher, Ord spent weeks at a time observing the male yellow-chinned anole lizard. He noticed that it defended its territory against other males with two types of displays. One is the subtle headbob. The other display is done with the flap of skin under its chin called a dewlap. When extended, it looks like an inflated bright yellow balloon. These two actions comprise the information-rich message that means, “I’m tough, so back off!”
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But sometimes the lizards would do exaggerated four-legged pushups before they gave this regular message. Was it just another way of flexing their muscles or was it an alert signal that the mostly silent lizards used to get their neighbor’s attention before “talking”? Ord suspected the latter was the case, and decided that the best way to talk to a lizard…was to be a lizard. Ord was at University of California at Davis and worked with Judy Stamps on this project. He now works at Harvard as well.
The Art and Science of Making a Robotic Lizard
Ord started with a cast of a real lizard using plaster of Paris. Next, he made a latex lizard and colored it with waterproof paint, using photos of real lizards as a reference. The dewlap was one of the most challenging parts because it had to look realistic as it inflated and it had to be the right color in order to fool the anoles. He thought of using balloons and other items before finally settling on pantyhose as the building material. After cutting and sewing it by hand, he made sure the paint color was realistic.
Then Ord programmed it to bob its head, extend its dewlap and do the mighty four-legged pushups. He powered it with batteries housed in plastic container, which he painted army green. He then attached the robot to the top of the container. Ord and his undergraduate assistants, Zac Costa and Shannon Seil, then packed up the robot and headed to the Luquillo Mountains in northeast Puerto Rico where real anoles are abundant.
Lizard Reality Show
There, the researchers set up a tripod and secured the electronic box with the robot attached horizontally. They placed it behind a tree so that to the real anoles, the robot would appear to be perched on a tree. Then they made the robot do the standard message alone and at other times preceded the message with the four-legged pushups. Ord and his team videotaped how the real anoles reacted.
The real anoles responded with their own displays more quickly when the pushup preceded the message, confirming that the pushup’s function is to grab attention. Ord also found that the real anoles, themselves, used the pushups more frequently under low visibility conditions such as when it was dark or there was a lot of visual distraction like trees blowing in the wind. The main part of the message, however, remained the same. Ord compares the pushup to a teacher rapping a ruling to get the attention of students. He published his results in the November 28th issue of the Proceedings of the National Academy of Sciences.
Ord’s experiment also shows that anoles try hard to avoid physical confrontations, even using the pushup that requires a large amount of energy expenditure.
“Animals, in general, try to avoid getting into physical fights because if you get into a fight you generally can get into some serious trouble in terms of injury,” he explains.
Ord says that since the robot just continues displaying, the real anoles would get annoyed and sometimes get aggressive enough to approach the robot. At that point Ord would stop the experiment to avoid damage to the robot.
But it wasn’t all fun. He and his assistants had to endure difficult conditions while conducting the experiment.
“Puerto Rico is very nice, but the reality is you’re also covered in mosquitoes, dripping with sweat, covered with mud, and sitting through torrential downpours every other hour,” Ord says. “Zac and Shannon were real troopers!”
When asked where he gets the patience and perseverance he explains, “When you’re out there and you have a robot and it’s essentially talking to the lizards and the lizards are responding back, it’s one of these really fascinating things that just sort of makes you realize how lucky we are in terms of the jobs that we actually have of studying these animals.”
PUBLICATION: The Proceedings of the National Academy of Sciences, November 24, 2008
RESEARCH FUNDED BY: National Geographic Society and the National Science Foundation
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