Astrobiology and the Limits of Life
The question of life — what it is, how it can be recognized, and where its limits lie — stands at the very core of astrobiology, often defined as the study of the origin, evolution, distribution, and future of life in the universe. However, this definition already contains a fundamental difficulty: to search for life beyond Earth, we must assume that we know what life is, and this assumption is inevitably rooted in our terrestrial experience.
Most astrobiological research focuses on approaches that are shaped by an implicit assumption: that life elsewhere resembles, at least at a fundamental level, life as we know it on Earth. The similarities we observe among life forms on Earth are not necessarily universal features of life as such, but rather the result of a shared evolutionary history on our planet. If our tools, models, and expectations are calibrated to terrestrial biology, radically different forms of life may remain invisible — not because they do not exist, but because they fall outside our conceptual framework.
Astrobiology thus finds itself in a tension: it must define life to detect it, yet every definition risks being too restrictive. This is not only a technical problem, but also a philosophical one, concerning the limits of knowledge and the conditions under which something can be recognized as living.
Rather than considering life as a property of isolated organisms, we should explore the possibility that it emerges from networks of interaction among organisms, environments, and planetary processes. To begin rethinking life beyond an individualistic and Earth-centered perspective, it is useful to return to the origins of life on our planet. In this context, the work of the American scientist Lynn Margulis represents a crucial shift, as it places microorganisms — rather than complex organisms — at the centre of planetary transformation.
Margulis showed that the earliest forms of life on Earth were microbial and that these organisms were not passive inhabitants of a given environment, but active agents in transforming planetary conditions. A significant example is the role of cyanobacteria in the oxygenation of the atmosphere: through photosynthesis, they gradually altered its chemical composition, making the emergence of more complex life forms possible.
From this perspective, life does not merely adapt to an environment, but co-constructs it. The Earth’s atmosphere, often considered a background condition, is in fact the result of biological activity, and the boundary between organism and environment becomes less defined. This challenges a static and localized conception of life, suggesting instead that it operates across multiple scales and through distributed processes.
Margulis is best known for the theory of endosymbiosis, according to which fundamental components of eukaryotic cells — such as mitochondria and chloroplasts — derive from independent bacteria that entered symbiotic relationships with other cells. Rather than being eliminated, these microorganisms were integrated, becoming constitutive parts of more complex cellular structures. Evolution, in this view, is driven not only by competition and selection, but also by cooperation and integration.
This introduces a significant shift from classical interpretations of Darwinism. While natural selection remains a fundamental mechanism, Margulis shows that complexity cannot be explained exclusively through competition. Symbiosis becomes a central driver of evolutionary innovation: life evolves not only through divergence, but also through association.
Similar dynamics can be observed in the plant world. Plants do not exist as isolated entities, but are embedded in complex networks involving soil, fungi, bacteria, and atmospheric exchanges. Root systems interact with microbial communities, giving rise to symbiotic relationships essential for nutrient exchange and growth. The plant, in this sense, is part of a broader ecological system, and its identity is relational rather than autonomous.
This has important implications for astrobiology. If life on Earth is relational and capable of transforming its environment, the search for life elsewhere may require a shift in perspective: not only the search for organisms, but the identification of processes and systemic effects. By placing microorganisms, symbiosis, and environmental transformation at the centre, Margulis builds a conceptual bridge toward a systemic understanding of life, further developed in the work of James Lovelock, who extends this understanding from the scale of microorganisms to that of the planet. With the Gaia hypothesis, the English scientist proposes a radical reconfiguration of how we think about life: no longer as something contained within individual organisms, but as a property of the Earth system itself.
According to Lovelock, the Earth can be understood as a self-regulating system in which biological and non-biological components interact to maintain conditions favorable to life. The atmosphere, oceans, soil, and living organisms are not separate domains, but interconnected elements of a complex system. This system is capable of stabilizing variables such as temperature, chemical composition, and salinity within ranges that allow life to persist. For instance, oxygen production by photosynthetic organisms, carbon dioxide absorption by plants and oceans, and microbial activity in the soil all contribute to shaping atmospheric conditions.
In this perspective, life is not simply something that exists within a stable environment: it actively participates in producing and maintaining that environment. The distinction between organism and environment thus becomes difficult to sustain, since what we call “environment” is largely the result of life itself, showing how life and the conditions of its existence are co-constitutive.
This Gaian perspective invites us to rethink what it would mean to encounter a form of life radically different from our own. The dominant scientific position on the origin of life is abiogenesis: the idea that life emerged on Earth from non-living chemical processes. According to this view, under specific environmental conditions — such as those of primordial oceans or mineral surfaces — complex organic molecules formed, eventually giving rise to self-replicating systems and, over time, to living organisms. This model is supported by an increasing body of research, yet remains incomplete: the precise steps through which the non-living became living are not fully understood.
Alongside this hypothesis, there is panspermia, according to which life — or at least its fundamental components — may have been transported through space via meteorites, comets, or interstellar dust. In this scenario, Earth would not be the sole cradle of life, but one of the places where it developed within a broader cosmic distribution. Panspermia remains, in my view, a theoretically powerful hypothesis. Neither position can be definitively confirmed or ruled out, and this uncertainty reveals that the problem is not only empirical, but also epistemological. The deeper difficulty concerns our ability to determine where life truly begins. Even when we imagine life elsewhere, we tend to project onto it the biochemical structures and organizational models we know from Earth. The decisive question then becomes: are we truly discovering life, or are we extending our own model of life to the universe?
To this conceptual limit, another — perhaps even more radical — must be added: the limit of perception. Here, the contribution of contemporary plant biology, and particularly the reflections of the Italian botanist Stefano Mancuso, becomes relevant. Plants show that different forms of life can be embedded in radically different temporalities. To us, they appear immobile, but this immobility is the result of our perceptual scale: their movements and processes unfold according to temporal rhythms that our senses are unable to directly grasp.
In this sense, the problem is not that plants do not move or act, but that we do not see them doing so. Their life unfolds before us within a temporality that escapes our immediate perception. Symmetrically, we too, for a plant, might appear too rapid to be perceived in our continuity. This temporal misalignment is philosophically decisive, because it shows that what we do not perceive is not necessarily absent.
This intuition has also been explored in narrative contexts. Some science fiction stories imagine scenarios in which an extraterrestrial civilization visits Earth but fails to recognize any form of life, because human beings appear immobile relative to their temporal scale. In such cases, what is lacking is not life, but the capacity to recognize it. The difficulty does not concern the existence of life, but its perceptual accessibility.
If this already holds at a theoretical level and, as the case of plants shows, also on Earth, then astrobiology must consider a more radical possibility: we may not be naturally equipped to perceive certain forms of life, not only extraterrestrial ones but also potentially co-present within our own world. There may exist forms of life whose speed or mode of manifestation exceeds the threshold of our senses. In this case, the problem would not be the absence of evidence, but the inadequacy of our perceptual apparatus to detect it. The search for life thus becomes inseparable from the limits of our cognition and our sensibility. Our instruments detect what they are designed to detect, our models interpret what we are able to think, and our senses return only a portion of reality.
It is precisely at this point — where empirical uncertainty meets conceptual and perceptual limits — that a rethinking of life becomes necessary, one that also concerns the role of technological mediations, capable of extending our perceptual capacities and opening research to forms of life that would otherwise remain invisible. It therefore becomes necessary to move beyond a strictly biological and static conception of organicity.
It is in this context that I introduce the concept of extended organicity — the object of investigation of my research. By “organicity” I do not simply mean what is biologically alive, but a mode of existence that emerges through dynamic interactions, exchanges, adaptations, and processes of integration. Organicity, in this sense, is not a substantial property, but rather a relational condition: something that takes shape through connections, feedback loops, and the capacity to maintain continuity with an environment. To speak of extended organicity means, in my view, recognizing that these characteristics are not necessarily limited to biological organisms, but may also emerge in broader systems — ecological, planetary, and technologically mediated — in which life is distributed and becomes perceptible through relations and processes rather than through mere biological entities.
At this point, however, the decisive theme becomes the function of technology as an extension of our cognitive and perceptual capacities. If the case of plants shows us that a form of life can remain almost invisible to our senses simply because it is embedded in a different temporality, then we must admit that the problem of searching for life cannot be entrusted solely to natural human perception. In this sense, the extension of perception discussed here should not be understood as a project of enhancing the human body or overcoming its biological limits, but rather as an expansion of the conditions through which reality becomes accessible.
Already today, we use technological tools to render perceptible what escapes our senses: microscopes to observe the cellular world, telescopes to detect distant signals, sensors to register imperceptible variations in temperature, radiation, frequency, or atmospheric composition, time-lapse techniques to make visible plant movements that appear absent to the naked eye. In all these cases, technology does not invent the phenomenon but allows us to access levels of reality that would otherwise remain unperceived.
This point is also fundamental for astrobiology. If there exist forms of life that operate according to temporalities, scales, or relational modes incompatible with immediate human perception, then technology can become not only a tool of measurement, but a true extension of the senses. The search for life thus also becomes a search for the conditions of its perceptibility.
From this perspective, the boundary between natural and artificial loses part of its rigidity. Technology no longer appears merely as a set of tools external to the living, but as a mode through which the living — particularly the human — extends its capacity to enter into relation with what would otherwise remain out of reach. Extended organicity, then, should not be thought only as an extension of life within techno-biological hybrids, but also as an extension of the conditions through which life itself becomes knowable. Here, technology does not serve to replace the living, but to mediate our relationship with it. Without these mediations, our idea of life would remain bound to a horizon that is too narrow.
If, instead, we accept that there may exist forms of life that are eccentric with respect to our experience, then technology becomes an integral part of the theoretical and experimental work of expanding the concept of life. In this sense, the question is no longer simply “what is life?”, but also “what tools do we need to perceive it?”, “what forms of existence escape us because our senses and our models are not yet adequate?”. Astrobiology thus becomes not only a science of elsewhere, but a critical practice that calls into question the limits of our terrestrial and human point of view.
Extended organicity therefore functions as both an epistemological and an ontological concept: on the one hand, it describes a form of life that exceeds the individual and is distributed across relations, systems, and mediations; on the other, it compels us to rethink the way we construct epistemic access to what we call the living.
From an astrobiological perspective, it also becomes necessary to reconsider what it would mean to encounter life beyond Earth. It would not simply involve adding a new object to scientific knowledge, but transforming the very framework through which we understand life and our place in the universe. In this sense, the encounter with a radically different form of life would also have a political dimension, as it would force a rethinking of the relations between human, non-human, environment, and forms of existence that exceed terrestrial categories.
Continuing to search for life would therefore not merely represent a scientific endeavour. It is also the expression of a certain orientation toward the unknown — a willingness to question our assumptions, to expand our conceptual frameworks, and to remain open to forms of existence that we are not yet able to fully understand. In this sense, the limits of life in astrobiology are not only constraints, but also openings. They mark the boundaries of what we currently know, but also indicate the directions in which our understanding can expand.
And in doing so, we may discover that the search for life beyond Earth leads us back to a more complex, more entangled, and more open understanding of life here on Earth — and of our place within it.
Rossella Vingelli is a PhD candidate in Philosophy at the University of Liverpool. Educated at the University of Naples Federico II, Royal Holloway, and Kingston University, her research focuses on contemporary transformations of the concept of life and on new philosophical and political perspectives emerging from the encounter between organisms, environments, and technologies. Alongside her philosophical research, she pursues an artistic practice encompassing photography, video, painting, and poetry, which she regards as complementary modes of inquiry into the complexity of living beings and their relationship with the world.
Website: www.rossellavingelli.com
Instagram: @rossellavingelli
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