- The paper presents a substrate-agnostic framework that unifies biosignatures, technosignatures, and ecologies by abstracting definitions of life, intelligence, and agency.
- It employs complexity metrics like epsilon machines and assembly indexes to quantitatively assess non-terrestrial, substrate-independent signatures in planetary data.
- It demonstrates that agent-driven environmental modification dissolves boundaries between biological and technological processes, informing novel detection strategies.
Substrate-Agnostic 3x: Reconceptualizing Signatures and Ecologies Beyond Terrestrial Constraints
Theoretical Motivation and Philosophical Context
"Substrate-Agnostic 3x: Biosignatures, Technosignatures, Ecologies" (2607.01664) develops a rigorous philosophical reframing of how biosignatures and technosignatures should be conceptualized and sought, especially in the context of astrobiology and SETI. The central thesis is that both biosignature and technosignature detection must be abstracted from parochial terrestrial biases. The argument is constructed on three ascending abstractions: definitions of life itself, definitions of intelligence/technology, and finally, their unification in a generalized ecological framework grounded in agency and niche construction.
The first abstraction is rooted in the recognition of the underdetermined nature of current biosignature inference, which always depends on tacit or explicit theoretical commitments about the nature of life. The paper traces the implications of David Duner’s semiotic framework, highlighting the ambiguity in associating empirical phenomena with claims about life in the absence of a universal theory. The proposed solution is to develop agnostic biosignatures—metrics or features not bound to terrestrial biochemistry or particular evolutionary histories.
A similar argument is constructed for the technosignature paradigm. The author problematizes the dichotomy between artifacts or modifications attributed to intelligence/technology and those considered strictly biological. The limiting factor is shown to be the lingering anthropocentric bias, both in scope and inference.
Agnostic Biosignatures: Complexity Metrics and Beyond
The paper conducts an incisive discussion of leading proposals for agnostic biosignatures, emphasizing those that operationalize substrate-agnostic traits via formal measures of complexity. The use of epsilon machines to estimate the statistical complexity of planetary time series is analyzed as a methodologically tractable, data-driven alternative to standard chemistry-centric biosignature frameworks. As detailed in Bartlett et al. [bartlett_assessing_2022], epsilon machines enable the quantification of regularities in observational data without invoking specific metabolic or biochemical pathways.
The assembly index, as discussed in Walker [walker_life_2024] and Sharma et al. [sharma_assembly_2023], is critically examined as an approach to substrate-independent historical depth. By measuring the minimal sequence of construction steps embedded in a system, the assembly index quantifies a generic marker of evolved complexity, positioning objects like Earth as possessing a temporal signature not trivially attributable to abiotic processes.
Consequently, the author positions the biosignature search as a search for genesity (the generic creative capacity of a planet), transcending habitability and admitting non-standard forms of life, in line with the lyfe framework [wong_searching_2022]. This abstraction incorporates the prior critiques of "life as we know it," providing a computational and historical pathway for expanding agnostic biosignature sets.
Agnostic Technosignatures: Environmental Modification, Agency, and the Collapse of Boundaries
The discourse on technosignatures is framed through evolutionary and ecological perspectives, with the concept of environmental modification as the foundational principle. The paper notes that classic definitions—such as Tarter’s [tarter_evolution_2007]—already admit technosignatures as detectable environmental changes, but these definitions often remain implicitly human-bound or artifact-centric. Drawing on analogies to archaeological and design theory, the author argues that the distinction between "natural" and "artificial" is contextually fragile and should be relinquished in favor of a spectrum of agency and modification.
Niche construction theory, as articulated in Laland et al. [laland_extended_2015] and [laland_introduction_2016], is invoked to formalize this substrate-agnostic view. Biological agents, regardless of their substrate, modify their environments in systematic, measurable ways—a process indistinguishable, at a certain abstraction level, from technologically driven modification. The notion of ecological inheritance—information structures (niches) persisting across generations—is extended to technospheric legacies, thus dissolving categorical boundaries between biosignatures and technosignatures.
The critical claim is that every technosignature is, under broad abstraction, a biosignature (contingent upon agentic activity), and, potentially, vice versa. This assertion challenges disciplinary orthodoxy in SETI and evolutionary biology and calls for a unified detection and interpretive framework.
Substrate-Agnostic Ecology: Agents, Niches, and Stigmergic Dynamics
Pushing to the third and most general level, the paper synthesizes the previous abstractions in a theory of substrate-agnostic ecology. Drawing on Haeckel’s classical definition and its modern elaborations, the author advances the thesis that the core object of interest—across biosignature, technosignature, and ecological domains—is the agent-environment coupling typified by reciprocal causation.
Niche construction embodies this reciprocal dynamic: organisms and agents modify their selective environments, which then feedback on their evolutionary (or otherwise adaptive) trajectories. Ecological inheritance, as a transmission channel distinct from genetic inheritance, is highlighted for its informational, substrate-independent character.
Significantly, the paper incorporates the concept of stigmergy—coordination via persistent environmental modifications [heylighen_stigmergy_2016]. At planetary scale, chemical, atmospheric, or morphological anomalies are interpreted as stigmergic traces pointing to the distributed activity of agents, whether biological, technological, or hybrid.
Consequently, the distinction between "biological" and "technological" is shown to be, in many cases, operationally irrelevant. What is privileged is the abstracted agent/agency and its ecological effects, formalized without ontological presuppositions on biochemical or material substrate.
Implications and Future Directions
The substrate-agnostic ecology position has substantial implications for the methodologies and priorities of astrobiology, SETI, environmental science, and the philosophy of life and technology. By formalizing the search in terms of agency and ecological modification, new observational strategies must be developed that emphasize complexity, assembly, and environmental information structures.
Practically, this framework broadens the scope of possible detection strategies beyond current template-matching for biochemistry or technology, enabling more general anomaly detection and interpretive models. Theoretically, the approach implies that future AI (including non-biological or hybrid intelligences), synthetic ecologies, and new forms of agentic systems could and should be incorporated into models of habitability and detectability.
The collapse of the boundary between biosignatures and technosignatures raises challenging questions for the definition of intelligence and life themselves. The paper references ongoing debates (cf. Agüera y Arcas [aguera_y_arcas_what_2025]) regarding the computational and evolutionary underpinnings of life, hinting at the need for an updated theoretical synthesis.
Conclusion
This work systematizes and advances the philosophy of substrate-agnostic science in astrobiology, SETI, and ecology. By grounding bio- and technosignature research in a general theory of agency, niche construction, and ecological modification, it reorients empirical and theoretical research towards a truly universalist, context-independent framework. This substrate-agnostic perspective opens significant avenues for future work on metrics, detection strategies, and the conceptual definition of intelligence, agency, and life in the cosmos.