Prof. Atsushi Iriki

Dr. Iriki

ISP2012 Lecture Course Abstract:

Neurobiology of primates' cognitive niche-construction

The evolution of human lineage has involved a continuous process of addition of new kinds of cognitive capacity, including those relating to manufacture and use of tools and to the establishment of linguistic faculties. The dramatic expansion of the brain that accompanied additions of new functional areas would have supported such continuous evolution. Extended brain functions would have driven rapid and drastic changes in the hominin ecological niche, which in turn demanded further brain resources to adapt to it. In this way, primate ancestors have constructed a novel niche in each of the ecological, cognitive and neural domains, whose interactions accelerated their individual evolution through a process of ‘triadic niche construction'. The brain's functional characteristics seem to play a key role in this triadic interaction.

Expansion (or increase in capacity) of organs as an adaptive response to ecological pressures seems to be a general biological and evolutionary tendency to make the phenotypic system robust—the brain will not be an exception. Multi-sensory integration and coordinate transformation for the control of reaching movements in the inhabited space is an essential function of the nervous system, for which evolution finally endowed primates with a well-developed parietal cortex. Such neural enhancement (construction of the neural niche) happened to enable the processing of abstract information, detached from actual physical constraint, by applying and re-using existing principles for spatial information processing to realize novel mental functions (construction of the cognitive niche)—ultimately leading to language. Purposeful manipulation of the body image in space, required for tool use, would have accelerated interactive links between the neural and cognitive niches—tool use requires transformation of various bodily and spatial coordinates, as well as logical and sequential relations of action components.

Tools represent materialized cognitive brain functions. They have been created one after another and incorporated into primate habitats as constituent elements (construction of the ecological niche). A primate-modified environment puts pressure on succeeding generations to adapt to it, perhaps by acquiring further resources for the relevant organs. Epigenetically induced plasticity (including developmental or learning mechanisms) would participate in such processes—and this is a subject for future biological investigations. In this way, extra genomic information could be transmitted between generations via mutual interactions among ecological, neural and cognitive domains of niches, which may have contributed to primates' evolutionary processes (that is, ‘triadic niche construction'). Primates', and eventually humans', higher cognitive activity can therefore be viewed holistically as one component in a terrestrial ecosystem.

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ISP2012 Abstracts