ABSTRACT PI: Bitterman PROPOSAL NUMBER: 9601991 Learning in an Invertebrate Although invertebrates comprise more than 95% of all animal species, there has been almost no systematic study of their intelligence. Few invertebrate species actually are suitable for the purpose, which requires that they be inexpensive and abundant, live well in or near the laboratory, and have manageable sensory, motor, and motivational properties. The investigators have been studying honeybees, highly evolved invertebrates which do meet those requirements and which are also of great economic importance (in honey production and the fertilization of crops). For the most part, they use individual foragers that come of their own accord to the laboratory, where they work for a highly concentrated sugar solution to take back to their hives- a solution that is preferred to the nectar provided by flowers in neighboring fields. The experiments carried out thus far point to close similarities in the learning of honeybees and vertebrates, which are surprising in view of the vast differences in brain structure and the remoteness of the evolutionary relationship. (The two lines of animals have evolved independently over a half-a-billion years from a simple common ancestor that seems to have had hardly any brain at all). If the similarities are to be understood in terms of random genetic variation in structure and natural selection based on similar environmental demands, those demands must be general indeed, since the environments vary widely in detail. It is possible, however, that evolution is a more organized process than is traditionally assumed and the avenues of change are more limited. As the tasks set for the animals become increasingly complex, the investigators can expect to find differences in performance that reflect the absence in A honeybees of certain advanced vertebrate capabilities-differences that should further their understanding both of the common and of the a dvanced capabilities. The present phase of the research deals with questions about the nature of reward; competition among concurrent sensory inputs; the relation between short-term and long-term memory; and the inhibitory control of behavior.
