A Little Like the Beach
On Friday afternoon, I sat on my knees in grainy gold dirt and tossed a piece of mushy grape onto a paper towel in front of me. It was hot, smolderingly hot, actually, and the ground was covered with black ants, rolling along with their little ball bodies scampering over the fallen pieces of grape that hadn't hit the paper towel (my aim is not that great).
"Cleomenis," I said. The female Lemur catta, or ring-tailed lemur had entered her sleep box. She showed no interest in participating in any silly human experiment, even if it involved grapes and bananas. "Cleomenis," I cooed. I couldn't help talking to her like she was a baby or a puppy. Ringtails, with their little black noses and round eyes are some of the cutest lemurs (actually, I can't rank them - they're all pretty cute).
Mosquitoes were particularly vengeful that afternoon. "They'll carry you away," a technician had warned my research partner Camila and I as we had walked to the outdoor silo that housed Cleomenis and her cagemate, Teres.
My name is Rachna Reddy. I am a rising sophmore at Duke, and part of the Howard Hughes Research Fellows program. This summer, I am continuing work in the lab of Dr. Brian Hare. Dr. Hare studies cognitive evolution in primates and canines. I am working on a project that investigates social inhibition across five species of lemur. My mentor is a graduate student, Evan Maclean, who is currently in the Congo studying bonobos and chimpanzees.
Camila and I spend each day out at the Duke Lemur Center. The DLC is home to about 250 prosimian primates, including lemurs, lorises and bush babies. Most of the lemur enclosures are outdoors, and in the summer many lemurs free-range in the Duke forest.
It's a different lab experience than most. I come home smelling like ringtail scent-mark and have to get sand out of my socks. "It's like being at the beach," Camila and I joked one day, dusting sand off our shorts and legs.
Here's the social inhibition experiment in a nutshell:
Two experimenters sit in front of a lemur. They each have a single piece of grape in one of their hands. They both hold the food out to the lemur, and it chooses one of them to approach. One of the experimenters is "mean." If the lemur approaches the "mean" experimenter's hand, he or she pulls it away. The "nice" experimenter allows the lemur to take the food. After ten trials of this, the "mean" experimenter adds more food to his or her hand. Then comes the real test. Has the lemur memorized the reputations of the mean and nice experimenters? And, is it able to inhibit its desire to run toward the greater amount of food?
Before we run this test, we run a pretest that animals must pass before moving on to the test. In the pretest, a single experimenter puts a piece of grape in one hand, and a greater amount of food (that includes yummy bananas and raisins) in the other. He or she then allows the lemur to approach and take food from one hand. The pretest is meant to ensure that lemurs prefer to have a greater amount of food.
Sometimes, though, lemurs, like Cleomenis, just aren’t interested in participating in the test. This unpredictability is probably the hardest part about working with animals. The amount of work you get done each day depends entirely upon what they feel like doing, no matter how long you sit in front of them with food in your hand.
The following photos are from Cleomenis' pretest. The dark blue gloves and masks are a precaution against swine flu. Usually, we do not wear them.
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Here are Cleomenis and Teres together.
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Here I am trying to lure Cleomenis to the ground.
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This shows part of the setup of the pretest. We videotape all the tests we run. Sometimes a particularly curious lemur will climb on the camera.
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