How did perception emerge from the mists of ancient evolution?

A naturalistic framework for the senses

Subjective experience, or the capacity for perception, is a characteristic of consciousness. A living thing is said to have sentience if “there is something about being that living thing.”¹ In his 2024 book From sensation to sensation,² Psychiatrist and neurologist Todd Feinberg focuses on the evolution of perception (the subjective “emotional” aspect of consciousness) and its personal nature. “Sentient” is of Latin origin. feelwhich means “to feel.”

The book expands on ideas from previous books and articles written with Feinberg’s collaborator, evolutionary biologist John Mallatt. together,³ They developed an evolutionary framework to understand how. early forms of consciousness⁴ Although it emerged as a natural property based on the fundamental biological properties of life, the emergence of subjective experience required the evolution of more complex neurobiological features.⁵

in From sensation to sensation, Feinberg proposes a new theory that he calls Neurobiological emergencyism it is based on biological, neurobiological, evolutionary A model that explains both sensations appear In addition to analyzing complex nervous systems, it is also possible to scientifically resolve the “explanatory gaps” between observable physical systems. nervous system and subjective experience.⁶

This theory traces the evolutionary process from the first stages of basic mechanical sensing in unicellular organisms. Unicellular organisms can be thought of as essentially biological machines lacking internal experience.⁷ Primitive animals that have some but not sufficient component of perception, animals that have rudimentary forms of subjective experience and therefore simple perception, and animals that are perhaps fully sentient.

emergence and complexity

Feinberg describes perception as emergency propertyarises from the hierarchical structure of the nervous system. Emergent phenomena exhibit new properties that naturally arise from the interactions of simple components within a complex system. These properties cannot be completely reduced to parts of the system. They reflect overall organization and complexity. For Feinberg, sensation is one such new property. Specifically, it is a “weak” phenomenon,⁸ That is, emergent properties can, in principle, be explained or derived from the underlying components or rules of the system, without the need to invoke metaphysical or non-reductive explanations.

Ability to define emergency systems:

• Complex system: Emergence occurs in systems with many interacting parts. Here, dynamic processes, rather than static components, are the key to creating new phenomena.
• New aggregate functions: Emergent properties are new capabilities that do not exist in individual parts but result from collective interactions, such as perception, which emerges from the coordinated activity of neurons in a structured nervous system.
• Hierarchical organization: Complex systems are organized hierarchically, with higher levels building on interactions at lower levels. These higher levels create new properties that are not reducible to the properties of the individual components.
• Constraints: Constraints resulting from interactions between lower-level components maintain the stability and consistency of complex systems. By imposing rules and limits on interactions, they shape how components across multiple levels work together and ensure that the system operates as a unified whole.⁹
• Mutual causation: Interactions within and between levels of the hierarchy are bidirectional. Higher levels guide and ensure global coherence (top-down causality), while lower levels shape and drive higher-level dynamics (bottom-up causality).
• Multiple possibilities: Emergency phenomena can occur due to differences in the composition of parts. For example, perception has evolved independently in vertebrates, arthropods, and cephalopods, showing how diverse neural structures can achieve similar outcomes through common principles of integration and organization. Masu.

The evolutionary path to sensation

In Feinberg’s model, the emergence of perception in evolution can be understood through three major stages, each characterized by increased biological and neural complexity.

The first stage is emergency stage 1,¹⁰ It began over 3.7 billion years ago with the emergence of life. Unicellular organisms have demonstrated fundamental biological functions such as metabolism and homeostasis, as well as responsiveness to environmental stimuli (i.e., mechanosensing) through photoreceptors, mechanoreceptors, and chemoreceptors. . These processes have enabled organisms to regulate their internal states and interact with the external world. Although these early life forms lacked subjective experience, they exhibited rudimentary forms of “interiority.”¹¹ Laying the foundation for a more advanced form of biological self.

second stage, emergency stage 2arose about 570 million years ago with the evolution of a simple nervous system. Evolved from multicellular animals with diffuse neural networks such as jellyfish, animals like bilaterally symmetric C. elegans have more centralized neural circuits (body The front part of the head) was developed. These systems have increased adaptability and enabled more complex interactions. environment. However, the simplicity of animals as “existing” animals limited their ability to generate unified mental representations and subjective experiences.

third stage, emergency stage 3 (ES3) characterized the evolutionary emergence of perception in animals with complex nervous systems. Between 560 million years ago and 520 million years ago,¹² Vertebrates, arthropods, and cephalopods have independently evolved sophisticated neural structures that can integrate sensory and emotional information into a unified mental state. Key innovations in ES3 Animals include:

New neural structures and processes supporting the emergence of sensation

• Brain with increased number of neurons (approximately > 100,000), allowing higher computational power and complexity.
• Many differentiated neuronal subtypesallowing for functional specialization and precise neural processing.
• sophisticated sense organswhich includes the image-forming eyes and tactile, auditory, and olfactory receptor systems, allowing detailed environmental awareness (exteroceptive mental imagery).¹³).
• A more fully developed neural infrastructure for emotion and painallowing for non-reflexive interoceptive emotions.¹⁴
• Expanding the neural hierarchy Extensive reciprocal neural interactions facilitate consistent integration of diverse inputs across sensory, motor, and emotional domains.

Mr. Feinberg is also on the list. New and emerging features related to the sensessummarized in footnote 15.

These innovations have enabled ES3 animals (including all vertebrates, some arthropods, including certain insects such as bees, and cephalopod molluscs such as octopuses) to have subjective experiences and adaptive, goal-oriented You can now perform directed actions.

sensory behavioral markers

Feinberg infers the existence of animal perception and identifies several important behavioral markers that can distinguish it from reflex responses or simple sensory processes, as listed in footnote 16.

Addressing descriptive gaps

The so-called “explanatory gap” highlights the challenge of bridging the subjective, first-person nature of experience and the objective, third-person explanation of the brain. Feinberg suggests: Neurobiological emergencyism leading to a scientific resolution of the actual relationship between the two. “Explanatory gaps”, both created by the natural biological manifestations of perception. These gaps are personal nature of sensation and qualitative nature of experience, The latter is a question of why the experience feels the way it does. specific their way (also called) qualia). But Feinberg suggests that instead of an “explanatory gap,” there is actually a gap. experience gap: Qualitative aspects of an organism’s experience are inherently subjective and therefore cannot be objectively explained. This division between subject and object is not an obstacle to a physicalist theory of consciousness.¹⁷

conclusion

in From sensation to sensationFeinberg presents perception as a “weak” and emergent phenomenon that arises naturally from complex neurobiological systems. These systems evolved as extensions of the basic biology of living agents. The emergence of perception was essentially determined by the gradual evolutionary increase of four variables: (1) the number of neurons, (2) the degree of specialized neural function, and (3) the level of neural hierarchy. number, and (4) degree of interaction between neural hierarchical levels.¹⁸ Complex systems of this kind have the property of being able to generate higher-level emergent features by coherently integrating sensory and emotional inputs through dynamic reciprocal feedback loops.¹⁹ Sentience is one such new capability, the property of an entire system working together resulting from the integration and interaction of a large number of component processes. Sensation, and more generally consciousness, is the integrated experience of a nervous system about itself and its relationship to the outside world.

See footnote 20 for ways in which the theory could be further strengthened and important elements that need further understanding.