Testing Monkeys—for Jealousy

Steven Pinker, Jane Goodall and Richard Wrangham sit on the tenth floor of William James Hall munching on Froot Loops. They shriek in unison whenever a stranger enters the room, and they poop all the time.

But it’s OK—they’re monkeys.

Pinker, Goodall, and Wrangham are members of a colony of approximately 24 cotton-top tamarins that dwell in Harvard’s Cognitive Evolutionary Laboratory. The lab, led by psychology professor Marc D. Hauser, tries to better understand human cognitive ability by studying our distant evolutionary cousins.

Researchers say the daily inter-species interactions allow them to form close relationships with their subjects.

“They have very unique individual personalities,” says Konika Banerjee ’08, an undergraduate researcher. “We get to know them really, really well.”

But beyond the monkey business, there is serious work being done. Another researcher, Kyle J. Foreman ’08, is working on a senior thesis—inspired by economic theory, of all things—that tests whether monkeys ever get jealous.

To an outside observer, the laboratory can seem like an impregnable fortress. To protect the monkeys, all researchers and visitors must undergo a $55 tuberculosis and allergy testing before they are allowed inside.

“As a result of that, we don’t have people coming into the lab who don’t work there, even though many students would love to bring their families,” says Hauser.

Security goes both ways—many of the monkeys will never see the outside world. Because cotton-top tamarins are on the list of endangered species, they cannot be given to zoos.

“They are kept there for the duration of their life,” says Ellyn M. Lane, member of the University’s Institutional Animal Care and Use Committee (IACUC). The only place where the monkeys can be transported is the New England Primate Research Center, which provided the original colony in 1992.

The daily lives of the monkeys are carefully regulated. All proposals for research using vertebrate animals have to be approved by the IACUC, which has to follow a complex web of federal, state, city, andUniversity guidelines that protect the monkeys from physical and psychological stress.

Tamarin health is checked weekly by veterinarians from Harvard’s Animal Resources Center and daily by the animal care staff, who look for signs of stress such as weight loss or pacing back and forth, according to Arthur L. Lage, the director of Harvard’s Animal Resources Center.

To ensure psychological well-being, the naturally social monkeys are also caged in groups or breeding pairs and are given means of “enrichment,” including swings, ropes, or problem-solving toys.

Foreman says he goes to the lab almost every day, checking on his experiments and working with two underclassmen who assist his research.

Foreman’s thesis was inspired by an economic theory that proposes the ability to behave altruistically or spitefully benefits an individual in the long term. Consideration of inequalities in rewards is common among humans, but Foreman’s question is whether perceived inequality could make tamarins engage in spiteful behavior, sacrificing a small reward in order to deny another monkey a larger one.

In almost every case, Foreman says, his monkeys act out of self-interest, with no consideration of rewards (in the form of Froot Loops) to other monkeys.

But Foreman has found that tamarins will, around 5 to 10 percent of the time, deny themselves one Froot Loop if accepting it would trigger a reward of four Froot Loops to another monkey.

Some of the lab’s most interesting insights come unexpectedly.

“One day I go into the colony room, and see a female hanging upside down, with her vaginal area facing a heater fan in the room,” Hauser writes in an e-mail. “I can’t quite understand why. Then I see her urinate into the fan, and bingo, a new function.” 

The monkey, Hauser says, had found a particularly efficient way to mark her territory.

“This female had worked out how to maximize technology,” Hauser writes, “spraying her urine all over the colony room.”

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