As Insect Societies Evolved, Brain Regions for Central Cognitive Processing Shrank; This Contrasts Sharply with Evolution of Vertebrate Societies That Is Associated with Brain Expansion

The society you live in can shape the complexity of your brain--and it does so differently for social insects than for humans and other vertebrate animals. A new comparative study of social and solitary wasp species suggests that, as social behavior evolved, the brain regions (mushroom bodies) for central cognitive processing in social insect species shrank. This is the opposite of the pattern of brain expansion with sociality that has been documented for several kinds of vertebrate animals, including mammals, birds, and fish. "By relying on group mates, insect colony members may afford to make less individual brain investment. We call this the ‘distributed cognition hypothesis,’" said Sean O'Donnell, Ph.D., a Professor at the Drexel University College of Arts and Sciences in Philadelphia, Pennsylvania, who led the study published on June 17, 2015 in Proceedings of the Royal Society B. The article is titled “Distributed Cognition and Social Brains: Reductions in Mushroom Body Investment Accompanied the Origins of Sociality in Wasps (Hymenoptera: Vespidae).” A highly informative video is also available at the following link: Essentially, Dr. O'Donnell says, the cooperative or integrative aspects of insect colonies, such as information sharing among colony mates, can reduce the need for individual cognition in these societies. The “distributed cognition hypothesis” contrasts sharply with the leading models of how the social complexity of vertebrate animals relates to their cognitive abilities. In vertebrates, more complex social environments generally demand more complex cognitive abilities in individuals.
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