Calvin’s Darwinian Mechanism in Neocortex

Neurobiologist William H. Calvin proposes that consciousness emerges as “the current winner of Darwinian copying competitions in cerebral cortex,” competitions among a multitude of subconscious mindsets—spatiotemporal firing patterns of cerebrocortical neurons, particularly within the association areas of the neocortex. This process is dynamic, not static, recursive, and shaped by selective pressures similar to natural selection.

In this view, consciousness is not a constant state of awareness but rather the fleeting victor in an ongoing Darwinian struggle within the brain. The ‘winning’ mindset gains temporary dominance, allowing it to control our thoughts, actions, and perception of reality (Calvin, 1998).

The selection of the ‘fittest’ mindset is not a random process but rather is influenced by our memories, current environment, and goals. The victorious thought pattern is the one that is most coherent and best suited to the present context. This winning ‘draft’ becomes our conscious awareness, while the others remain in the background, ready to compete for dominance in the next moment. This continuous cycle of generation, competition, and selection allows for a flexible and adaptive consciousness that can navigate a complex and ever-changing world.

The Darwinian Mechanism

Calvin’s Darwinian mechanism explains how the widespread wiring principle of recurrent excitatory circuitry of mammalian neocortex can run “the six essential features of the classical Darwinian process: a pattern (spatiotemporal firing pattern of a Hebbian cell-assembly, in this case) that copies with occasional variation, where populations of the variants compete for a limited work space, their relative success biased by a multi-faceted environment (both memorized and real-time, in this case), and with further variations centered on the more successful of the current generation (Darwin’s inheritance principle)” (Calvin, 1998).

The actual nexus of consciousness arises from the competition between ‘hexagonal mosaics’—collections of synchronized, triangular arrays of pyramidal neurons in the neocortex. These mosaics compete for space and influence within the cortical landscape. The dominant pattern at any given moment governs the contents of consciousness—perception, thought, or motor planning.

As Calvin puts it, “Hexagonal mosaics are like plainchant choirs, singing in the lockstep of a Gregorian chant.… Perhaps choosing between an apple and a banana for a snack is a matter of how big their respective choirs are, that only large choruses can gain access to the output pathways associated with silent speech.”

Tunes, Creativity, and Problem-Solving

Each hexagonal cortical patch encodes a spatiotemporal ‘tune’—like a musical motif representing a concept or memory. “A hexagon’s spatiotemporal firing pattern is potentially a cerebral code, what represents an object or idea. Such a pattern is like a little tune (map each of the several hundred minicolumns to a note on a musical scale). There will be a different tune characterizing Apple than the tune for Banana.”

Thus, consciousness involves not just these ‘tunes,’ but their recombination and harmonization—e.g., combining ‘banana’ and ‘yellow’ arrays—which may enable abstract thinking, metaphor, and analogical reasoning.

Crucially, consciousness enables problem-solving and creativity by bootstrapping novel ideas into high-quality thoughts. The cortical Darwinian machine can, within seconds to minutes, perform analogs of biological evolution. Calvin says, “There is a pattern that is copied … variations occur … populations of the variant patterns compete … and the more successful of the current patterns tend to produce more of the next round of variants” (Calvin, 1998).

For Calvin, there is no fixed ‘center’ of consciousness: “The ‘centre of consciousness’ could … shift from moment to moment: from language to nonlanguage areas, from frontal to parietal lobe, from left to right hemisphere, and maybe even from cortical to subcortical structures.” This dynamic shifting allows for multiple simultaneous tasks, layered processing, and a spectrum of awareness from unconscious routines to highly resource-demanding creative thought.

Levels of Explanation and Higher-Order Processes

Calvin aligns with William James's notion of the stream of consciousness and integrates ideas from chaotic attractors: “Resonances are better known these days as part of the rubric of chaotic attractors. I imagine each hexagon’s neural network as supporting a number of characteristic spatiotemporal patterns.” He likens memory layers and their lingering influence on thought to sashimi slices or fallen dominos, shaping the likelihood of new thoughts—a model for creativity and memory-triggered associations.

Calvin focuses on “the appropriate levels of explanation (ranging from quantum aspects to association cortex dynamics),” lamenting that “What’s missing from most discussions of consciousness is, surprisingly, the whole concept that there are levels of explanation.”

He critiques theories that attempt to locate consciousness in quantum mechanics: “Consciousness … certainly isn’t located down in the basement of chemistry or the subbasement of physics. This attempt to leap … from the sub-basement of quantum mechanics to the penthouse of consciousness is what I call the Janitor’s Dream.” He notes “the scanty evidence relating quantum fields to cortical synchrony” (Calvin, 1998).

Instead, he stresses that “[A] more appropriate level of inquiry into consciousness is probably at a level of organization immediately subjacent to that of perception and planning: likely (in my view) cerebral-cortex circuitry and dynamic self-organization involving firing patterns within a constantly shifting quiltwork of postage-stamp-sized cortical regions.”

Novel properties emerge from these “middle-level cortical structures (the 0.5 mm hexagonal cortical regions), where patterns can self-organize, entrain others, and compete — all while being modifiable by experience and memory” (Calvin, 1998).

Calvin’s model allows for a hierarchical web of Darwinian processes, including a ‘supervisory Darwinian process’ capable of influencing or biasing the operations of other, lower-level Darwinian processes. This means that slower meta-level processes (possibly involving frontal or orbital cortex) could steer faster, lower-level perceptual or motor Darwinian competitions—akin to agenda setting or task-switching.

This also suggests a hierarchy in the selection process, potentially enabling more abstract or complex forms of consciousness. Calvin stresses the role of language in structuring these competing thoughts, seeing it as a crucial tool for the development of higher-level consciousness (Calvin, 1998).