Conceptualising Suspended Life: From Latency to Liminality

Abstract

The article focuses on the ability of some animals and plants to respond to changing environmental conditions by temporarily suspending metabolic processes. In contemporary biology, this state between life and death is commonly labelled ‘cryptobiosis’, combining the Greek kryptos (hidden, concealed, secret) with biōsis (mode of life). I argue that the notion of ‘cryptobiosis’ does not account sufficiently for the processual and relational dimensions of ametabolic life. The article advances a related but different concept, which better addresses this liminal state of biological organisation: suspended life. While cryptobiosis still nurtures the imaginary of some latent life, suspended life stresses the liminality of the neither-nor life and death. The notion also grasps the dynamic and ongoing transfer between the biological and the technological. While the debate on cryptobiosis has so far remained confined to the description of natural processes, suspended life (or limbiosis) promises to account for contemporary technological practices of cryopreservation.

It’s life, Jim, but not as we know it. (Star Trekkin’)

About a decade ago, the anthropologist and STS scholar Stefan Helmreich (2011) noted that ‘life’ – the theoretical object of biology since the emergence of the discipline in the early 19th century – has been undergoing an important transformation recently. While it was for a long time considered a stable and solid reference point for research, defined by criteria such as self-reproduction and autonomy (Toepfer, 2005; Morange, 2008), it has now been ‘morphed as material components of living things – cells and genes – that are rearranged and dispersed, and frozen, amplified, and exchanged within and across laboratories’ (Helmreich, 2011: 673). Drawing on ethnographic fieldwork with contemporary biologists working in novel research fields such as artificial life and astrobiology, Helmreich argued that it is increasingly unclear where life begins and where it ends: ‘It is a question about limits, a worry about ends. What was life?’ (Helmreich, 2011: 675; emphasis in original.)

This paper follows a similar but slightly different path of problematisation. Rather than engaging ethnographically with cutting edge research on ‘limit biologies’ (Helmreich, 2011: 676) to determine what distinguishes life from nonlife, I attend to a well-known liminal state widely discussed in biology. I will focus on a phenomenon that was observed by natural scientists even before the advent of modern biology: the ability of some animals and plants to respond to changing environmental conditions by temporarily arresting metabolic processes. Showing no visible sign of life, these organisms appear to be dead but can return to vital activity once a more favourable environmental constellation arises. For example, certain microorganisms such as rotifers, tardigrades, and nematodes are able to survive the loss of their body fluid. While the desiccated animals shrink in size and appear lifeless, they swell and rapidly resume their normal metabolism once they are immersed in water again. Apart from dehydration, this ametabolic state might be caused by a range of other (adverse) environmental conditions, e.g. freezing cold, high salt concentration or lack of oxygen (Crowe, 1975; Wright et al., 1992; Wharton, 2002).

In contemporary biology, this liminal state between life and death is commonly labelled ‘cryptobiosis’ (Clegg, 2001; Wright, 2001; Neuman, 2006; Withers and Cooper, 2010; Cannone et al., 2017). The term combines the Greek kryptos (hidden, concealed, secret) with biōsis (mode of life). Biologists investigating this ‘latent life’ often describe it as ‘obscure’ (Guppy, 2004: 436), a biological phenomenon still ‘unexplored’ (Jönsson and Järemo, 2003: 331), or an unsolved ‘major problem in contemporary biology’ (Feofilova, 2003: 1). This assessment most certainly reflects the dearth of empirical studies on this topic. So far, research has focused on a rather limited number of organisms (Wright, 2001) and has not been able to identify the essential molecular mechanisms and biochemical processes associated with cryptobiosis (Watanabe et al., 2002; Schill et al., 2004; Guppy, 2004).

However, the current scientific consensus that cryptobiosis is ‘poorly understood’ (Wright, 2001: 564) and remains a ‘mystery’ (Neuman, 2006: 259) might also result from conceptual problems. In this article I argue that the focus on latency and potentiality suggested by the term cryptobiosis does not account sufficiently for the processual and relational dimensions of the phenomenon in question. I will refer to and further advance a related but different concept, which better addresses this liminal state of biological organisation: suspended life. While this notion existed alongside ‘latent life’ for a long time in the history of biology, it was significantly less frequently employed to describe the (at least in principle) reversible stillstand of metabolic processes. As I will argue, ‘suspended life’ not only better attends to the liminalities associated with this ‘unique biological state between life and death’ (Neuman, 2006: 260); it also captures the dynamic and ongoing transfer between the biological and the technological, the natural and the cultural.

The concept of suspended life promises to go beyond the limits of the debate on cryptobiosis, which has so far remained confined to the description of natural processes as it addresses contemporary technological practices of cryopreservation. Given the increasing scientific as well as social relevance of frozen cells or tissue in specialised cryobanks, covering a spectrum from reproductive technologies via regenerative medicine to biodiversity conservation and beyond, it is necessary to account for the diverse forms and fields in which ‘interrupted life’ (Anderson, 2015: 379) has been made available. The concept also sheds light on the repercussions of a ‘politics of suspension’ (Lemke, 2021), as the control of the temporal dimension of life and the suppression of metabolic activities gives rise to a specific mode of future-making by prolonging the present and ensuring technical disposition. This makes it possible to put the stored biomaterial in a state of suspension, avoiding irreversible developments and keeping options open (even for yet unknown purposes).

The argument is organised as follows. I will start with a brief historical reconstruction that distinguishes two important steps in the analysis of ametabolic life: the idea of a resurrection from death in the 18th century and the emergence of the notion of ‘latent life’ in the 19th century. The second part presents several conceptual proposals made in the more recent past to denote this ‘peculiar biological phenomenon’ (Baumann, 1922: 502). I will examine David Keilin’s introduction of the term cryptobiosis in the mid-20th century to rectify the semantic vagueness attached to earlier conceptual propositions and assess the terminological precisions he offers to account for different forms of ametabolic life. The third part argues for a shift from latency to suspension. While the notion of cryptobiosis still nurtures the imaginary of some residual life waiting to become active again, I introduce the neologism ‘limbiosis’ to stress the liminality of the neither-nor or in-between life and death. As the fourth section demonstrates, this conceptual proposition will enable us to address two major problems associated with the term cryptobiosis: a structuralist approach that juxtaposes potential and actual life, and an essentialist account that conceives of life as an inherent capacity of an individual organism instead of understanding it as an emergent property. The conclusion sums up the main argument and briefly points to the theoretical, empirical and methodological prospects of the turn to suspended life.

A Very Short History of Latent Life

At the beginning of the 18th century, the natural scientist Antoni van Leeuwenhoek reported a curious discovery to the Royal Society of London. Using the microscope he had developed, Leeuwenhoek observed the effects of desiccation on certain microorganisms (probably rotifers) living in the moss of roofs and the sand of the roof-gutters: ‘I found that when almost all the water was evaporated, so that the creature was no longer covered with water, nor could move itself as usual, it then contracted itself into an oval figure, and in that state it remained, nor could I perceive that the moisture evaporated from its body, for it preserved its oval and round shape unhurt’ (Leeuwenhoek, 1807 [1702]: 211). Leeuwenhoek undertook some more experiments with these ‘apparently dead’ (Leeuwenhoek, 1807 [1702]: 212) animals. He placed the completely dried out and motionless organisms in glass tubes and poured some water on them: ‘I stirred the whole about [. . .] and perceived some of the Animalcules lying closely heaped together. In a short time afterward they began to extend their bodies, and in half an hour at least an hundred of them were swimming about the glass’ (Leeuwenhoek, 1807 [1702]: 212; see Keilin, 1959: 150–2; Schmidt, 1918).

While Leeuwenhoek’s experiments clearly demonstrated that the microorganisms in question could survive in a desiccated state for several months, he did not connect his empirical observations to conceptual explorations concerning the border between life and death – a question that would occupy biological research following his pioneering work. Most scientists in the 18th century who conducted experiments in the wake of Leeuwenhoek’s original reports were convinced that the dried animals had actually died and returned to life once they were moistened (Baumann, 1922; Crowe and Cooper, 1971). The prospect of resuscitation resonated well with the era of Enlightenment and its ambition to discover the mysteries of death (Gruman, 1966). ¹

The 19th century witnessed an intensive scientific debate on whether or not microorganisms that showed no visible sign of life were indeed dead. To grasp the curious biological state of organisms that did not exhibit any vital activities but might resume them at some point in the future, researchers in biology and medicine introduced the notion of ‘latent life’ in the first half of the century. In 1834, the medical doctor and philosopher Carl Gustav Carus distinguished between ‘two states of any activity or any substance, namely, one where the same is free and determinate with all signs of its peculiar movement and motion, and one where its appearance is for the moment, as it were, annihilated or suspended and yet the existence of the substance must be admitted’ (Carus, 1834: 553). ² Following this empirical distinction, Carus identified a ‘latent’ form of life different from ‘manifest life’ (Carus, 1834: 554), in which he included, for example, seeds that have been stored for centuries without losing their germination capacity. The idea of a form of latent life that is characterised by a temporary and reversible stillstand continued to inform empirical research, and effectively shaped biological theory in the 19th century and beyond (Bauer, 1823; Ehrenberg, 1838; Doyère, 1842; Broca, 1860; Bernard, 1974 [1878]).

From the end of the 19th century onwards, the observation of natural phenomena was complemented by a growing interest in the technical operations of artificial cold and spurred by important advances in low temperature physics (cryogenics). The successful liquefaction of gases such as oxygen or helium generated temperatures close to zero Kelvin or absolute zero, shifting the research focus from desiccated animals to frozen organisms (Parry, 2004). In an article published in 1897, Horace T. Brown and F. Escombe reported the results of an experiment in which they had exposed different seeds for several days to a temperature of around −190 degrees Celsius. After slowly thawing them, the seeds did not show any observable difference in their germinating capacity compared to that of a control group. Brown and Escombe concluded that these findings ‘necessitate some modifications in the current ideas of the nature of life’, arguing that the concept of life goes beyond ‘vital activity’ (Brown and Escombe, 1897: 164). Taking up this line of thought, in an article in Science entitled ‘What Is Life?’ some years later, Joseph Le Conte suggested distinguishing between different ‘conditions of protoplasm’: ‘(1) living, a condition in which life is actual; (2) potentially living, in which the necessary molecular constitution or vital constitution is present; and (3) dead, in which the vital constitution also is wanting’ (1901: 992; emphases in original; see also De Candolle, 1885). ³

The advances in cryogenics and empirical research on the effects of low temperatures on organisms in the first part of the 20th century made possible the emergence of cryobiology in the aftermath of the Second World War (Luyet and Gehenio, 1940; Polge et al., 1949; Keilin, 1959; Smith, 1961; Kavaler, 1972). Since then, the science of ‘frosty life’ (Parkes, 1964) has become an expanding and successful branch of scientific research and a thriving field of technical application. More and more cell types and tissues can now be successfully frosted and thawed, and cryopreservation practices and technologies of cold storage have been widely used to preserve plant and animal materials such as seeds, semen and blood by cooling them to sub-zero temperatures.

Terminological Choices and Conceptual Clarifications: Proposing Cryptobiosis

Faced with the considerable scientific and technological innovations in cryobiology, in the late 1950s the biologist David Keilin undertook a comprehensive historical study of empirical research on the ‘state of an organism when its metabolic activity is at its lowest ebb [. . .], the physiological and biochemical processes being reversibly arrested for different periods of time’ (Keilin, 1959: 150). While since the first half of the 19th century the term ‘latent life’ had become the most prominent concept, ‘a confusing array’ (Withers and Cooper, 2010: 3) of alternative terms was also being used by this time to designate this specific biological state. Keilin engages with two of them in particular: anabiosis and abiosis.

The first term was introduced by the physiologist Wilhelm Preyer in the second half of the 19th century (Preyer, 1872, 1891). It is derived from the Greek ana (again, anew) and biōsis to denote a return to life or a regaining of vital activity from a seemingly dead, or at least inert, organism. However, Preyer and other researchers also used anabiosis to describe the state of an organism which is ‘lifeless but viable’ (Preyer, 1891, cited by Keilin, 1959: 166). To avoid this semantic ambiguity, in the mid-20th century Peter Schmidt suggested the term abiosis (Schmidt, 1948; Bernstein, 2019: 215). Keilin rules out this conceptual alternative, as the term is literally too close to the notions ‘abiotic’ and ‘abiogenesis’ – which have a very different meaning in the research literature, as they focus on the problem of the origin of life (Keilin, 1959: 166). To avoid terminological confusion and to improve conceptual clarity Keilin coined the notion of cryptobiosis, combining the Greek kryptos (hidden, concealed, secret) with biōsis. This defines a condition of ‘latent life’, designating ‘the state of an organism when it shows no visible signs of life and when its metabolic activity becomes hardly measurable, or comes reversibly to a stillstand’ (Keilin, 1959: 166). Thus, Keilin displaced the conceptual focus from a return from death or a renewal of life in order to affirm the idea of a ‘hidden life’, using the notions ‘cryptobiosis’ and ‘latent life’ interchangeably.

In addition to introducing the neologism ‘cryptobiosis’, Keilin suggested two important conceptual precisions. The first concerns the semantic question of what levels of metabolic activity are covered by the new term. In the history of biology it is possible to identify two different and contradictory understandings of latent life: one that identifies a ‘minimal life’ defined by a decelerated metabolic exchange, and another one which assumes that any metabolic activity has come to a complete stillstand (see Baumann, 1922). Keilin takes up the term hypobiosis, introduced by Bruno Monterosso (1934) to acknowledge the spectrum of different states of an organism exhibiting a low or no metabolism. In his reading, hypobiosis includes both dormant conditions of animals and plants (e.g. hibernation or diapause) which are associated with a still measurable metabolism and a temporary termination of growth, development and physical activity (in animals), and conditions where metabolic processes have ceased completely. Compared to the more comprehensive term hypobiosis, cryptobiosis is more delimited as it is reserved for a total suppression of metabolic activities (Keilin, 1959: 166–7).

Secondly, Keilin proposed an important systematic clarification as he distinguished several (adverse) environmental conditions that may engender the state of dormant or latent life: desiccation, cooling, lack of oxygen and high salt concentration (or a combination of them). While the term anhydrobiosis had already been introduced by Alfred Giard (1894), Keilin additionally coined the notions of cryobiosis, osmobiosis and anoxybiosis (Keilin, 1959: 167; Crowe, 1975; Clegg, 2001). This conceptual differentiation offered new research perspectives to explore differences and similarities between particular forms of ametabolic life (Wright et al., 1992; Wright, 2001).

Keilin’s conceptual innovations were extremely influential and had a substantial impact on future research in biology and beyond. ⁴ However, while the concept of cryptobiosis still informs current debates and research activities, Keilin’s terminological considerations are also overdetermined by the historical context of his work. It is no accident that cryobiological research flourished during the Cold War in the second half of the 20th century. The potential of nuclear destruction ‘froze’ the geostrategic borderlines between the two political and military blocs and fostered the development of technologies that sought to safeguard the continuity of vital systems and ensure survival in a post-apocalyptic age (Radin, 2017; see also Collier and Lakoff, 2021). In this constellation, the concept of cryptobiosis as well as the search for hidden or concealed forms of life were very much part of a Cold War imaginary and of cybernetic ideas of life as information: ‘In this respect, the term is a product of its time – at mid-century, life had become a coding problem, as cryptologists joined with cyberneticians seeking to “crack” the “genetic code”. A cold biology crystallised in the Cold War. A postwar problem, latent life became a cipher to be decrypted, a pregnant pause awaiting reanimation’ (Roosth, 2014: 66; see also Lethen, 1991; Kay, 2000).

While this historical context does not necessarily restrict the conceptual usefulness of ‘cryptobiosis’, there are also serious analytic problems associated with the idea of latent life, as we will see in the next sections. To overcome these limitations, I will suggest turning to a notion that has been employed in the history of biology for a long time but is strangely absent in Keilin’s account: suspended life. ⁵

From Latency to Suspension: Moving Beyond Potentialities to Investigate Practices

Mobilised in fields as diverse as architecture, geology, law, rhetoric, music, biology, chemistry and physics, ‘suspension’ offers a rich semantic repertoire to grasp the unsettling liminal state in which a biological substance is neither fully alive nor finally dead. Liminality denotes a threshold and boundary experience, referring ‘at once to the passage from one state to another and the moment of transition, being in-between, neither one thing nor another, or both one thing and the other, or perhaps best of all caught between the no-longer and the not-yet’ (Wischermann and Howell, 2018: 2; emphases in original). ⁶ Suspended life is located in this liminal landscape, articulating a state of hovering and floating, being in limbo or in a ‘condition of being hung’ (Oxford English Dictionary, 2021). The term ‘suspension’ renders problematic fixed boundaries and established categories, privileging the precarious and the provisional (Oxford English Dictionary, 2021; Grimms Wörterbuch, 1971). ⁷

While ‘latency’ stresses the potential of life forms and their concealed dimensions, ‘suspension’ opens up the analysis to include the actual practices that bring along a new ‘form of life’ (Helmreich and Roosth, 2010; Helmreich, 2011). ⁸ It shifts the analytic focus from observing to making. What has been framed in terms of cryptobiosis is no longer exclusively a natural phenomenon but has increasingly become a practical problem addressed by technologies of freezing. Today, the impact of cryopreservation is not limited to the field of reproduction but also affects biomedical research, regenerative medicine, transplantation surgery, conservation biology and biosecurity preparedness (Landecker, 2007; Friese, 2013; Lewis et al., 2016; Keck, 2017). The term ‘suspended life’ articulates the prospect of interrupting and restarting metabolic processes, bringing the generation and growth of cells and tissues to a temporary halt – a ‘pause’ – in order to allow storage for an indefinite period of time (at least in principle). The technological option of successfully freezing and thawing biospecimens has fostered the development of a new archival apparatus to store vital matter at low temperatures for long or (possibly) indefinite periods of time: cryobanks. These ‘frozen archives’ (Anderson, 2015) are not restricted to whole animals or plants but mostly contain ‘body parts’ (see Hacking, 2002) or ‘embodied bits of vitality’ (Helmreich, 2011: 673). They assemble different cell types and organic material stored to be used for reanimation, reproduction or regeneration purposes. By reassembling ‘natural’ specimens that differ in size and provenance, and by arresting metabolic activities to prevent them from growing or perishing, these repositories now resemble ‘a kind of immortal, artificial body’ (Parry, 2004: 403). Their inventory includes human as well as non-human materials, and they are animated by scientifically and medically sound but also by speculative or utopian practices, such as the cryonic hope for eternal life. ⁹

To better conceive of this peculiar ontological state, I propose the term ‘suspended life’ or ‘limbiosis’, combing the Latin word limen (threshold, doorstep) with the Greek notion biōsis, instead of cryptobiosis. The shift to suspension helps to erase the ambiguity attached to ‘latency’, as that term assumes the (hidden) existence of some residual life. The concept of cryptobiosis suffers from a logical paradox as the viability in ametabolic organisms could be ‘recognized in retrospect only after they revive’ (Roosth, 2014: 64). The diagnosis of latent life affirms the present absence of metabolic activities while simultaneously nurturing the promise of their future continuation. In contrast, the term ‘suspended life’ situates vital processes in a limbo instead of imagining a present but hidden capacity. It addresses two fundamental problems associated with the concept of cryptobiosis. The first problem lies in a structuralist approach that juxtaposes potential and actual life, the second in an essentialist account that focuses on biological properties of individual organisms instead of ecological relations.

Responding to Vital Problems: Interrogating Structuralist and Essentialist Concepts of Life

Shifting the analytic focus to limbiosis promises to circumvent a number of dualisms found in too many research papers on latent life. Biologists exploring cryptobiosis generally endorse an understanding of life that distinguishes a more fundamental structure from (less basic) vital processes. The empirical studies and the conceptual arguments on cryptobiosis often suffer from a hidden Platonism in which life ‘becomes synonymous with that of the structure, which supports all the components of its catalytic systems’ (Keilin, 1959: 187). This structuralist account neatly opposes latent to manifest life, perpetuating a dualism of activity and passivity, cause and effect. As Basile Luyet and Marie Pierre Gehenio put it in their classic book on cryopreservation: ‘life is probably conditioned by some special structure which, at low temperatures, allows for a state of latent life and at higher temperatures furnishes the basic mechanism for vital activities; the destruction of this structure would induce death’ (Luyet and Gehenio, 1940: 256; see also Carrel, 1910: 460). ¹⁰

This dualistic conception of life as either latent or manifest has governed cryptobiotic research in the past century, understanding life ‘in terms of the continuity of organized structure’ (Crowe and Cooper, 1971: 36). Biologists have advanced the ‘hypothesis that the force which controls the vital activities requires a special structure of matter, and that, when the structure is maintained, the protoplasm is alive, though it might not be active’ (Luyet and Gehenio, 1940: 255; emphasis in original; Roosth, 2014: 66–7). From this perspective, latent life is more (or rather less) than vital activities as it depends on an antecedent, permanent but concealed organisation that ensures continuity by disrupting metabolic processes. To be more precise, it is exactly the absence of metabolic activities that conditions the presence of life in this reading – an inert life without (apparent) changes. Thus, cryptobiosis lacks all signs of (what we knew as) life: it is a ‘life, not itself’ (Roosth, 2014: 56). However, rather than juxtaposing potential and actual life, it seems more appropriate to stress the liminality of this ‘peculiar state of biological organization’ (Clegg, 2001: 613). Instead of investigating the hidden complexities of latent life, the concept of suspended life undermines our conventional understanding of life (and death), inviting the prospect of a ‘temporary death’ (Neuman, 2006: 260; emphasis in original). It articulates the curious ontological state of the in-between or neither-nor – conceiving of it less as a state or a structure than as a passage and a process.

Suspension also better captures the relational dimension of ametabolic life. The notion of latent life is often reserved for a state where ‘the capacity for life is present but not apparent’ (Wharton, 2002: 7). According to this reading, life is an inherent property of isolated organisms. It might exist in a manifest or latent form but it is detectable and explainable at the level of the individual organism, defined by distinctive criteria like metabolic processes or a fundamental structure that sustains (and suppresses) vital activities. However, the concept of latent life and its analytic focus on interior causes risks nurturing gene-centred and essentialist accounts of biology. The emphasis on internal (often genetic) structures and processes combined with the neglect of ecological factors and developmental processes results in a one-sided and distorted account of organisms (see Oyama, 2000; Ingold, 2008; Kirksey and Helmreich, 2010; Van Dooren, 2016). ¹¹ Recent developments in the life sciences have revealed the profound significance of interspecies relationships, problematising the conventional understanding of biological individuals. They have increasingly challenged the ‘classical conception of an insular individuality into one in which interactive relationships among species blur the boundaries of the organism’ (Gilbert et al., 2012: 326; Nicholson and Dupré, 2018).

The analytic focus on life as a property of individual organisms is often informed by a control imaginary that still defines biological research on cryptobiosis and beyond. It conceives of vital processes as being ‘under the control of the organism’ (Hinton, 1968: 43) and understands the challenge of latent life in terms of ‘metabolic control’ (Guppy, 2004: 440). This line of argumentation often results in regarding cryptobiosis as a feature of ‘primitive forms of life’ (Hinton, 1968: 53) or associating it with ‘lower organisms’ (Jönsson and Järemo, 2003: 331). To acknowledge the complexity of regulatory processes, it is necessary to displace this essentialist understanding in favour of a more relational account, shifting the analytic accent from metabolic control to ‘metabolic networks’ (Neuman, 2006: 263). ¹²

It is also important to disturb the prevailing isolationist account in cryptobiotic research that juxtaposes activity and passivity, the physiology of individual organisms and external environmental conditions. Taking up and further advancing Lynn Margulis’ understanding of symbiosis, Donna Haraway has proposed a radical relational concept of life that focuses on interspecies entanglements and processes of ‘becoming-with’ (2016: 12; Margulis, 1998). In her reading, the term sympoiesis operates as an antidote to the idea of self-organising units that are capable of reproducing and maintaining themselves by regulating their composition and boundaries (autopoiesis). It articulates mutual dependencies rather than individual autonomy in conceptualising processes of life, going beyond the boundaries of single organisms by putting the emphasis on collective exchanges of energy and information (Haraway, 2016: 33, 61). In this sympoietic perspective, life is not a cause or an essence but rather the outcome of an assemblage in which the very existence of organisms depends on the interactions and conjunctions with other organisms and the material environment. Similarly, the philosopher of biology John Dupré has suggested that ‘functional biological wholes, the entities that we primarily think of as organisms, are in fact cooperating assemblies of a wide variety of lineage-forming entities’ (2012: 126; see also Margulis, 1998; Gilbert et al., 2012; Nicholson and Dupré, 2018). ¹³

The limbiotic concept of life recognises the fundamental biological importance of sympoietic processes, conceiving of life as resulting from processes of mutual emergence and co-constitution instead of an inherent capacity of an individual organism. This analytic frame also questions the understanding of life as organic and the difference between organic and inorganic, as it puts the accent on the material ‘milieu’ that allows living entities to emerge and to maintain their existence. In this light, the narrative according to which cryobiotes react to an ‘extreme’, ‘harsh’, ‘hostile’ or ‘inhospitable’ environment by slowing down or arresting their metabolic activities is misleading as it ignores the relational dimension of ametabolic life. As Helmreich reminds us, these characterisations need to be analysed in context: ‘Humans might be imagined as aerophiles, air lovers – an extreme from the vantage point of anaerobes. The “extreme” functions as a relativist rather than totalising operator. What this accomplishes is attention to environment’ (Helmreich, 2011: 688; see also Neuman, 2006: 265; Schrader, 2010). ¹⁴ In this limbiotic account, the milieu might be conceived of as a natural environment but it could also operate as a technological infrastructure (encompassing, e.g., nitrogen tanks or cryoprotectants that make it possible to freeze and store organic material such as semen, oocytes, embryos, tissues, etc.). ¹⁵ Thus, life is not a given attribute but depends on mutual exchange and material conditions of existence within and beyond biological processes. ¹⁶

In sum, suspended life redirects attention from vital capacities to ecological conditions that make it possible to arrest metabolic processes for some period of time. The term better captures the techno-ecological milieus that constitute the threshold between life forms and forms of life, the biological and the technical. ¹⁷ In this perspective, the biospecimens suspended in the cryobanks resemble electronic devices and material infrastructures on standby, being neither completely on nor entirely off. These limbiotes operate in a ‘sleep mode’, ¹⁸ representing a dynamic stillstand, always supposedly ready to be reactivated, a liminal ‘state of “in|activity” that indicates readiness without immediate engagement’ (Kemmer et al., 2021: 1).

Conclusion

In his article on the problematisation of the concept of life, Helmreich (2011) identifies a major shift that occurred in the course of the 20th century. He notes that Erwin Schrödinger’s widely cited essay What Is Life? (1944) proposed to conceive of life in informatic and cybernetic terms, understanding it as self-sustaining and continuously reproducing matter. This conceptual proposal significantly shaped the subsequent search for a way of ‘cracking the genetic code’. It gave rise to the idea of uncovering ‘the secret of life’, finally equating vital processes with the biochemical structure of DNA. In this view, life was primarily seen as genetic information (Kay, 2000; Morange, 2008: 1–24). ¹⁹ Towards the end of the century, Lynn Margulis and Dorion Sagan published a book with the same title (What Is Life?) – but provided a very different answer to the question (Margulis and Sagan, 1996). In contrast to the uniqueness of the genetic information that is shared by all organisms, they stressed the diversity of life forms (bacteria, protoctists, animals, fungi, and plants) and their specific features and differences. During the heyday of the Human Genome Project, which conceived of biological processes in informational terms, Margulis and Sagan noted that life cannot be reduced to the genetic sequence, emphasising interdependencies and the relational bonds between living entities: ‘If Schrödinger’s model fit into forms of life calibrated to Cold War practices of coding, secrecy, and cryptography, Margulis and Sagan’s view speaks to a world in which environmentalism and biodiversity – and their unknown futures – organize contemporary forms of hope and worry’ (Helmreich, 2011: 674).

In this paper I have proposed a related shift concerning the concept of latent life, arguing that it is time to leave behind the narrative of hidden codes waiting to be deciphered in favour of alternative imaginaries that stress processuality and relationality. Displacing the notion of cryptobiosis, the conceptual frame of suspended life offers new theoretical, methodological and empirical avenues.

In empirical terms, the turn to limbiosis invites a more complex understanding of the technological proliferation of cryopreserved organic material in many different societal fields. Cryopreservation practices extend the present by reserving time and suppressing metabolic processes, delaying change and ensuring reversibility. Rather than engaging with embodied, situated and finite living entities, they enact disembodied and decontextualised organic material or genetic information. ‘Cryogenic life’ (Friedrich and Höhne, 2014: 2) gives rise to a specific mode of future-making by prolonging the present and ensuring technical disposition. It helps to keep temporal horizons open and offers additional technological options for dealing with individual uncertainties and collective risks (see, e.g., Van de Wiel, 2020; Wolff, 2021). Thus, the techno-material emergence of suspended life has moulded temporal pathways and horizons and engendered new spatial configurations, making organic material available for different purposes and future usages (Lemke, 2021).

Methodologically, the uptake of suspended life redirects attention from the search for some hidden and mysterious quality of life in general to the specific practices that sustain forms of ametabolic life. This shift problematises conventional biological understandings of life focusing on self-sustainability and metabolic control and replaces them with ecological concepts that stress interdependency, co-emergence and co-becoming. ²⁰ Finally, suspended life also offers new theoretical perspectives as it articulates the threshold and the traffic between the biological and the technological. It goes beyond a purely descriptive account of organisms that are naturally capable of reversibly suspending vital activities and provides an exploratory concept that makes it possible to examine the technical storage and thawing of organic material by means of artificial cold. Suspended life also invites us to examine the intersections of informational and biological knowledge, in order to analyse how the idea of a ‘back up’ guides and shapes cryobanking practices. Thus, it focuses on forms of ametabolic life in both nature and culture and attends to the temporal and ontological liminalities they enact.