Week 5: Iriki & Taoka (2012) Triadic (ecological, neural, cognitive) niche construction: a scenario of human brain evolution extrapolating tool use and language from the control of reaching actions.

Having examined the major overall framework of niche construction we then turned to a specific – and quite speculative – application of the framework. Iriki & Taoka’s paper claims to look at niche construction on three levels of analysis (although there is a question here about whether they might be levels of nature): ecological, neural, and cognitive.

This paper generated a lot of debate about what a niche is, and whether Iriki & Taoka had distorted the idea in an unhelpful or unclear way in order to claim that it applies at the neural level.

The paper also included a very extensive survey of both their own research into tool use in Japanese macaques and also a range of neurological studies about brain regions which then used as the basis for a rather speculative but very interesting just-so-story (which I have attempted to replicate in the above diagram). They claim that the evolution of higher cognitive capacities arises through embodied engagements with space and features of space (such as tools) and how this could scaffold or open up space for capacities such as language. This involves the evolution of the body plan from a simple tube-like form, to one with an articulated neck and then to one with manipulable limbs. But it also involves the claim that tool-use exploits a redundancy in the body-schema of the organism which is there to accommodate growth. And thus, claim Iriki & Taoka, the tool becomes incorporated into the organism’s body schema through this redundancy – which itself then goes on to open up new conceptual spaces. This is a very strong embodied thesis about which there were very mixed reactions. I think this is quite interesting but I would be interested to know whether one could spell out other evolutionary paths (e.g. octopuses) and what inferences one would make about their cognitive capacities as a result. But it is also important to note that it relies on quite a strong reading of the embodied metaphor work of George Lakoff.

Returning to the research on Japanese Macaques. After two weeks of training, they can be taught to use rakes to gain access to food that they would not otherwise be able to reach. They do not use tools in the wild. This capacity for training requires the ability to reorganise the body schema/image. And indeed it is found that the visual field changes its focus with training to realign on the tool as if it were incorporated into the system. And this is matched by changing neural activity: “…hands are extended towards tools (externalization of the innate body) or tools are assimilated into the body schema (internalization of external objects)”. Progress from “enactive representation” to iconic and symbolic representation – this is a developmental process. They also trained some monkeys to use video-monitors to retrieve food out of sight: I&T interpret this to mean that “the body image is visually projected onto the distant monitor screen.” If monkeys can be trained to do both these tasks they can then move on to multiple tool use, which I&T propose requires (proto-)symbolic representation (pp. 11-12). The results of the experiment showed macro- and micro-scopic changes and expansion (up to 23%) detected in grey matter of the monkeys. In the intraparietal cortex based on a voxel based morphometry analysis – this included both axonogenesis and synaptogenesis. And this expansion spilled over into the adjacent secondary somatosensory area and the surrounding opercular cortex. (p. 12) As such, “…exposure to a novel cultural environment induces the brain to exhibit not only functional plasticity, but also extensive and persistent morphological change” (p. 13). And Iriki & Taoka consider what the evolutionary mechanisms that facilitate this brain expansion are; and postulate that it could be that systems must have redundancy that allows for changes and noise in the environment in the coordination of their body schemas. It is “…bistable or polysemous […and…] This functional plasticity may be an inherent property at the margins of a neural coding system” which is ready for changes to body or noise – this is hijacked or cannibalised (p. 13). I think this is a really important point for understanding our interaction with both mental and physical tools – and there are several points of connection here to the work of Lev Vygotsky (1985) on internalisation and Richard Menary (2010, 2014) on the manipulation thesis – by which it is the learning of normative patterned practices that generates both neuro-architectural and cognitive functional changes.





Iriki & Taoka 2012 Triadic (ecological, neural, cognitive) niche construction: a scenario of human brain evolution extrapolating tool use and language from the control of reaching actions. Philosophical Transactions of the Royal Society B: Biological Sciences, 367, 10-23.

Menary 2010 Dimensions of mind. Phenomenology and Cognitive Science, 9, 561-578.

Menary 2014 Neural Plasticity, Neuronal Recycling and Niche Construction. Mind and Language, 29(3), 286-303.

Vygotsky 1985 The Social Origins of Higher Mental Functions. (pp. 58-76) in Wertsch, J. V. (ed.) Vygotsky and the Social Formation of Mind. Cambridge, MA: Harvard University Press.


Interesting related links:

Here is a video of one of the authors, Atushi Iriki, discussing social neuroscience and the East-West divide. And here he uses the notion of triadic niche construction.


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