Scientists have long known that many of the behaviors of lower organisms are innate. In the insect world, for example, instinctive behaviors predominate. Birds have a larger repertoire of fixed behaviors than dogs.

In primates, voluntary or learned behavior predominates, so neuroscientists have assumed that the hard-wiring in primate brains is limited to simple movements and complex behaviors are all learned.

Now, however, studies are finding that a number of surprisingly complex behaviors appear to be built into the brains of primates as well.

These are "biologically significant" behaviors that appear likely to improve the primate's ability to survive and reproduce. They include aggressive facial patterns, defensive forelimb movements, and hand-to-mouth and reaching-and-grasping movements.

Vanderbilt researchers, writing this week in the Proceedings of the National Academy of Sciences Online Early Edition, report that they can elicit these complex behaviors by stimulating specific areas in the brain of a small nocturnal primate called the Galago or bush baby (Otolemur garnetti). Their results provide significant new support for the proposition that all primate brains, including our own, contain such a repertoire of innate complex behaviors.

"We have now seen this feature in the brain of an Old World monkey and New World prosimian. The fact that it appears in the brains of two such divergent primates suggests that this form of organization evolved very early in the development of primates. That, in turn, suggests that it is characteristic of all primate brains, including the human brain," says Jon Kaas, the head of the research group, Distinguished Professor of Psychology at Vanderbilt University an
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Contact: David F. Salisbury
david.salisbury@vanderbilt.edu
615-343-6803
Vanderbilt University
15-Mar-2005