The Emergence of Signs in the Primordial World
Imagine a world without interpreters—a primordial Earth where chemical reactions proceeded mindlessly, and molecules collided without purpose or intention. Now ask: How did these same molecules become messages, signs, and instructions? How did chemistry give birth to meaning?
This is the fundamental question addressed by Terrence Deacon in his groundbreaking work "How Molecules Became Signs" and the subsequent response to commentaries titled "Minimal Properties of a Natural Semiotic System" 1 . At the intersection of biology, chemistry, and philosophy lies the relatively new science of biosemiotics—the study of signs and meaning in living systems. Deacon's work represents a bold attempt to resolve one of the most persistent mysteries in science: how semiotic properties (the capacity to represent, refer, and signify) emerge from physical-chemical processes that otherwise lack these properties 1 7 .
"Every manifestation of information, semiosis and meaning we have been able to study experimentally has a physical form." 1
This article will explore Deacon's fascinating proposal that the simplest molecular systems capable of genuine semiosis—sign processes—may resemble what he calls "autogenic viruses." These are not parasites like modern viruses but self-repairing, self-replicating molecular complexes that exemplify how molecules might have first crossed the threshold from mere chemistry to meaningful communication 1 . By examining this research, we'll uncover what it truly takes for nature to move from reacting to interpreting.
Biosemiotics extends this concept to biological processes, suggesting that cells interpret molecules much like we interpret signs 9 . When DNA directs protein synthesis, it's not merely a chemical reaction—it's a semiotic process where nucleotide sequences "stand for" amino acid sequences 6 9 .
Understanding how molecules became signs requires recognizing the hierarchy of signification.
The fundamental mystery is how this representational relationship emerged from a world without interpreters. Deacon approaches this by asking: "What sort of process is necessary and sufficient to treat a molecule as a sign?" 8 . The answer requires identifying the minimal properties that enable a physical system to use one molecule as a sign representing something else 1 .
Most theories of life's origins begin with cells. Deacon makes a crucial shift by starting with a virus-like paradigm 1 . Why? Because viruses straddle the boundary between life and non-life, making them ideal models for studying the emergence of semiotic properties.
The autogenic virus (literally "self-generating virus") is Deacon's proposed minimal model system—a molecular complex capable of:
Unlike parasitic viruses, autogenic viruses are self-sustaining systems that maintain their organization through semiotic constraints rather than just chemical bonds.
The autogenic virus concept describes a molecular system where:
This self-maintaining organization creates the necessary conditions for molecules to acquire meaning—a particular molecule comes to "stand for" the process of restoration or for other molecules in the system 1 .
To understand how we might study minimal semiotic systems, it's helpful to consider the essential "tools" and components required for such investigations:
| Component | Function | Research Context |
|---|---|---|
| Catalytic molecules | Enable self-repair and reciprocal maintenance | Based on known catalytic chemistry 1 |
| Template molecules | Provide scaffold for replication | Similar to polynucleotide function 1 |
| Laboratory models | Test semiotic emergence | "Thought experiments" with empirical implications 1 |
| Graphical communication tasks | Study sign emergence in humans | Experimental semiotics paradigm 3 |
While the autogenic virus remains largely a "thought experiment," Deacon predicts these systems will eventually be discovered in environments like seawater or deep petroleum deposits, or even on other planets 1 .
The chemical plausibility suggests they could be found with relatively simple search procedures.
Meanwhile, related fields like experimental semiotics are studying how novel communication systems emerge in laboratory settings with human participants 3 .
These studies provide insights into how signs bootstrap themselves into existence, complementing the theoretical work on molecular semiosis.
Deacon proposes that semiotic properties emerged through a three-stage scaffolding process that parallels the icon-index-symbol hierarchy 1 8 .
The first stage involves self-assembly and self-repair based on molecular shape complementarity. Here, molecules interact based on physical-chemical affinities—like a key fitting a lock. This creates the foundation for iconic relations where molecular structures "resemble" their functional partners 1 .
Similarity
Shape complementarity in self-assembly
The second stage emerges when molecular interactions create stable, self-reinforcing cycles. A particular molecule comes to indicate the presence of other components or the state of the system—like smoke indicating fire. This establishes indexical relations based on causal connections rather than mere similarity 1 .
Causal connection
Metabolic cycle intermediates
The most sophisticated stage emerges with template-based replication, where a molecule (like DNA or RNA) stands for something else (like a protein) without physically resembling it. This represents a symbolic relation—the molecule becomes a symbol for something else, enabling referential displacement 1 8 .
Conventional relation
DNA-protein coding
Deacon's approach leads to a dramatic reversal of conventional biological wisdom. Rather than treating DNA as the source of biological information, he argues that DNA and RNA are semiotic artifacts—molecules that acquired their signifying properties through being used by interpretive systems 8 .
This perspective resolves a longstanding paradox: how can molecules be "about" something else? The answer lies not in the molecules alone but in the self-maintaining organization of systems that use them 1 .
Perhaps most significantly, Deacon's model aims to resolve the major incompatibilities between biosemiotic and natural science accounts of living processes 1 4 7 .
By providing a plausible, empirically testable model for how semiotic properties emerge from purely physical-chemical processes, it offers to naturalize meaning without reducing it to mere chemistry.
Deacon's work on minimal semiotic systems represents more than just a specialized inquiry—it addresses one of the deepest questions about life and meaning. How does a world of mere matter give rise to interpretation, representation, and signification?
The autogenic virus model suggests that the key lies in self-maintaining organizations that create the necessary conditions for molecules to acquire meaning. By identifying the minimal properties required for natural semiotic systems, this research helps illuminate the mysterious transition from chemistry to semiosis, from reaction to interpretation.
As we continue to explore these fundamental questions, we may find that life itself is characterized not merely by its chemical basis but by its semiotic nature—the capacity to create and interpret signs, a capacity that appears to have molecular roots extending back to life's very origins.
What makes Deacon's approach particularly compelling is its commitment to explaining semiosis using only known physics and chemistry, avoiding any special forces or mystical vitalism 1 . As he notes, "Every manifestation of information, semiosis and meaning we have been able to study experimentally has a physical form" 1 . The challenge—and the achievement—is to show how that physical form can come to mean.