When Gerald Edelman claimed that his theory of neuronal group selection was “completing Darwin’s programme,” he meant something far more profound than an analogy between evolution and learning. He was identifying the same selectional logic — variation, differential stabilisation, systemic coherence — operating not across populations of organisms, but within the dynamic field of the brain itself. In doing so, he relocated evolution’s relational principle from biology to semiosis: the brain as an evolving ecology of meaning.
1. The exhaustion of representation
By the mid-20th century, neuroscience had largely adopted the computational metaphor: the brain as a symbol processor, representing the external world through coded neural states. But this model depended on a stable correspondence between world and code — a logic of representation that Darwin’s own theory had already undermined. If evolution demonstrates that all forms are contingent stabilisations of relational interaction, then no representation could ever be privileged or complete. Edelman’s project began where the representational paradigm reached its limit.
2. The biological inheritance
Darwin’s logic provided the template: a system in which variation is abundant, constraints are local, and coherence emerges through selective stabilisation. Neuronal group selection transposes this logic inward. Neurons do not store representations; they form populations that compete and cooperate through patterns of connectivity. What persists are not images of the world but successful alignments within it. This is selectional dynamics at the level of meaning formation.
3. Plasticity and degeneracy
The conceptual breakthrough enabling Edelman’s model was the recognition that the brain is both plastic (capable of reorganising its structure) and degenerate (able to produce similar functions through different neural configurations). Degeneracy undermines the idea of one-to-one mapping between stimulus and response — just as Darwin undermined the notion of fixed species–trait correspondences. Meaning becomes distributed, adaptive, and contingent, sustained by the system’s capacity for multiple realisations.
4. Reentrance and recursion
Edelman introduced reentrant signalling — the bidirectional, recursive exchange among neural groups — as the mechanism through which coherence emerges. This is not information processing but relational synchronisation: a system achieving internal alignment without external supervision. It is through reentrance that perception, memory, and consciousness emerge — not as representations but as co-ordinations of activity, each construal selecting itself into being through dynamic fit.
5. From Darwin to Edelman: evolution turns inward
The preconditions of neuronal group selection, then, were not primarily empirical but ontological. Once the logic of natural selection had displaced essence with relation, it became possible to conceive of cognition itself as a selectional process. Edelman’s innovation was to see that evolution could occur within a lifetime — that the brain’s ongoing self-organisation was itself a continuation of Darwinian logic. Evolution, in this view, did not stop with the body: it entered the domain of meaning, completing Darwin’s programme by extending selection into semiosis.
No comments:
Post a Comment