Neurobiology of Civilization: Evolution through Primates’ Social Interaction
Atsushi Iriki
RIKEN Brain Science Institute, Japan
Several recent studies report how laboratory-raised, nonhuman primates exposed to tool use can exhibit intelligent behaviors, such as imitation and reference vocal control, that are never seen in their wild counterparts. We trained Japanese monkeys to use tools, and observed neurophysiological, molecular genetic and morphological changes within their brains that enables to incorporate tools into their own body schema. Despite being ‘artificially’ induced, these novel behaviors and neural connectivity patterns reveal overlap with those of humans. Thus, they may provide us with a novel experimental platform for studying the mechanisms of human intelligence, for revealing the evolutionary path that created these mechanisms.
As our ancestors’ array of tools and tool-modified environment increased in size and complexity, selective pressure would have favored individuals that were more adept at acquiring and mastering them. Although each step in this evolution might have been a simple association, it eventually may have produced something beyond. One such candidate could be the concept of the ‘self’, which would have emerged through the self-objectification process to incorporate tools into their user’s body schema. This would allow tool users to take third-person perspective of the self, through which in turn the sense of equivalence among the self and the others emerge. Such objective self-other relationships are coded as neuronal activities of tool-using primates, which would further trigger neural changes described above.
Thus, tool-induced environmental construction became ‘intentional’, which remarkably accelerated the speed of evolution. Now, the direction of evolution was no longer passively determined by the natural selection, but the organisms themselves, through social interactions, could decide how the environment should and could be remade. Each new iteration of the human-altered civilized environment would have influenced the development of the next generation’s brains.