Until now, primatologists believed lemurs to be primitive, ancient offshoots of the primate family tree, with far less intelligence than their more sophisticated cousins, monkeys, apes, and humans. But at the Duke Primate Center, with the gentle touch of his nose to a computer screen, Aristides, a ringtail lemur, is teaching psychologist Elizabeth Brannon a startling scientific lesson--that lemurs are, indeed, intelligent creatures.
Brannon is using touch-screens, Plexiglas boxes holding raisins, and buckets hiding grapes to establish that ringtails such as Aristides and his mongoose lemur cousins possess a surprising ability to learn sequences of pictures and to discriminate quantities. While Brannon's work is at a preliminary stage, its initial results lead her to believe that such studies could mark the dawning of a new appreciation of lemur intelligence, and offer important evolutionary insights into the nature of intelligence in primates.
Brannon, an assistant professor of psychological and brain sciences and a member of Duke's Center for Cognitive Neuroscience, says lemurs are living models for the ancient primate mind. Prosimians, including lemurs and related species, split off from the primate line some 55-million years ago, evolving independently of anthropoids and humans. "One of the main threads of my research has been to understand how the human mind became so sophisticated numerically," she says. "A big issue is whether primates have specific adaptations for such cognitive abilities that differ from other animals. And prosimians are a great model for these basal primate adaptations."
When she and her student researchers began to offer ringtails the chance to use a touch-screen to recognize images for a sugar-lump reward, the animals literally jumped at the chance. "The ringtails live in social groups, which could be distracting, and they're completely free to just ignore us and the apparatus. Despite these possible complications, we found they would completely, voluntarily come over to the screen and participate."