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The evolution of intelligence in a model invertebrade system
University of Louisville The evolution of intelligence is both one of the most fascinating, and yet most difficult, issues in the field of behavioral studies. Most current models of intelligence assume that it evolved primarily in response to selection pressures associated with living in complex social environments. The animals usually associated with intelligence -- apes, dolphins, parrots, humans -- are cared for by parents, and are sheltered and protected throughout most of their development. Such vertebrates continue to benefit from social exposure to others, and their life spans exceed several decades, allowing individuals a tremendous amount of time in which to develop complex learning. At the same time, apes, dolphins, parrots, and humans are extraordinarily difficult to use in controlled experiments on intelligence. Ideally, we would like to work on intelligence in a species that is known to display complex behavior, takes well to the laboratory, and is amenable to controlled experimentation. Evidence suggests that octopuses may be just such creatures. What makes octopuses an even more appealing model system for studying the evolution of intelligence is that their life histories are very different from those of vertebrates, suggesting that new models of intelligence may be necessary in the future. Hatched in vast numbers and dispersed as plankton, most octopuses spend the first portion of their lives drifting with the current, and usually only 1/100,000 achieve sexual maturity. This allows no learning about survival from an older generation, no play with peers to hone down important skills or imitative behaviors, and indeed few or no environmental cues about which the organism can construct a frame of reference as it develops. Further, most species have life spans between 9 and 18 months and remain solitary throughout their entire lives, except during matings or conflicts. Yet octopuses have demonstrated remarkable learning abilities with respect to such tasks as solving complicated puzzles and mazes. I am will run a series of experiments looking at complex learning in octopuses. Ruling out or confirmation of complex learning in an octopus model system could change the way scientists think about the evolution of cognition, and might also affect the placement of social learning within the hierarchy of intellectual skills measured in animals. If in fact complex learning evolved in parallel between vertebrates and invertebrates-groups whose genomes diverged some 1.2 billion years ago-many long-held theories about our own intelligence may need to be reevaluated.
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