The Shadow Biosphere Hypothesis: Non-knowledge in Emerging Disciplines

Abstract

All life on Earth shares the same ancestor, the most primitive form of life that arose, in still unknown circumstances, more than 3.5 billion years ago. At least this is what is commonly assumed. Astrobiologists have revisited this assumption and advanced the hypothesis of the existence of a “shadow biosphere” on Earth: a parallel tree of life whose instances, being different at the molecular level to the kind of life we are used to, would remain hidden from view. In this paper, I take the emergence of the so-called shadow biosphere hypothesis and the controversial discovery of GFAJ-1, a microbe thriving in the arsenic-rich waters of Mono Lake, as an entry point to look into the strategic role of non-knowledge claims. I juxtapose the Latourian black-box, that is, those undiscussed technoscientific artifacts that are taken for granted in scientific practice, with the shadowy nature of non-knowledge claims in order to pay closer attention to the contingent, active, performative, and always social nature of the making of what is unknown. I conclude this paper by claiming that in the negotiation of what is unknown, emerging disciplines position themselves within the larger scientific community.

Keywords

black-box unknown non-knowledge shadow biosphere astrobiology

GFAJ-1 is a potato-shaped microbe that, for a few weeks in 2010, shook the foundations of biology. Found within a series of water and mud samples collected by the National Aeronautics and Space Administration (NASA)-funded scientist Felisa Wolfe-Simon on the shores of Mono Lake, a body of water on the eastern slopes of the Sierra Nevada mountain range, the microbe had been transferred to a US Geological Survey lab and cultured within an arsenic-rich and phosphorous-depleted growth medium. According to Wolfe-Simon and her team,¹ the observations performed in the laboratory showed that, when starved of phosphorus, one of the six fundamental elements that every living being uses to build its molecules, this microbe seemed able to do something no other known organism could: replace it with another molecule similar in structure but usually considered very poisonous, arsenic (Wolfe-Simon et al. 2011). The discovery, published in the prestigious scientific journal Science and concomitantly presented at a press conference hosted38 by NASA, was portrayed as so exceptional as to demand textbooks to be rewritten because it would suggest, in Wolfe-Simon’s (2010) words, “a different way to be alive. And if that were true,” she added, “what else might we be able to replace? And if you can replace it, could it be evolved completely independently?”

The release of Wolfe-Simon’s paper and NASA’s fanfare were met with contrasting reactions: while some fellow scientists were praising Wolfe-Simon’s groundbreaking findings, others did not withhold their doubts and made public criticisms on personal blogs and social media.² Several biologists declared the article “shameful” (Redfield 2010) due to the science being so bad (according to their standards), and in a few months, a number of formal and informal publications described what they considered valid evidence³ to disprove Wolfe-Simon’s findings. No traces of arsenic in the GFAJ-1’s DNA and a high preference for phosphorus constituted, according to the critics, “just the last nail in the coffin” (Cressey 2012) of arsenic-based biology. To the many critiques, Wolfe-Simon replied by politely welcoming the new experimental results as a direct consequence of her study; in her view, the series of follow-ups “represents the kind of careful study that really helps the community,” but, she pointed out, these works “do not necessarily rule out an entirely novel mechanism” and “there’s still a lot of interesting open questions” (see Note 3).

The exchange deploys many terms and expressions related to the “opening/closure” semantic domain; where biologists could see “relatively definitive refutations” (Borhani in Hayden 2012) of the discovery, Wolfe-Simon (2010) saw the possibility to “crack open the door” to a new epistemic space (Rheinberger 1997; Hackett 2005) filled with unanswered questions and unknowns. In this paper, I do not attempt to document the closure of this controversy. On the contrary, I want to use it as an entrance point to explore the active, performative, and situated movements of opening achieved by means of future-oriented claims about what is still unknown.

Unpacking Black-boxes: Janus’s Third Face

In the opening of his book Science in Action, Latour (1987) introduces the reader to the mythological figure of Janus Bifrons, the two-headed deity borrowed from Ancient Roman folklore. Janus is represented with both a young and a mature face, each speaking for science at a different stage of its unfolding: science in the making and all made science. While science in the making is uncertain, involving many people at work, harsh competition, and provisional decisions, all made science is certain, cold, and unproblematic. When science is in the making, concepts and devices are questioned, deconstructed, and reassembled; when science is all made, on the other hand, the complex chain of social relationships and alliances that made it possible are hidden from view. The achievement of this latter stage is what Bruno Latour called a black-box: the functioning of an artifact, either a technological device or a scientific concept, comes to be accepted and then taken for granted.⁴ All the elements that used to be questioned and reassembled, at this stage, flawlessly work as a whole (Latour 1987). Because looking into the artifact’s complex internal functioning becomes unnecessary and inconvenient, black-boxes are first of all practical achievements that make communication more efficient and simplify usage, thus defining a shared paradigm for practitioners. Black-boxes are not intended to exclude ways of thinking or experimenting, but in hiding the complex chain of decisions that came to constitute them, they also prevent change. This is why, when science is made, opening a black-box becomes, according to Latour, an almost impossible task. This is what makes Janus, as a narrative device, necessary: “the impossible task of opening the black-box is made feasible (if not easy) by moving in time and space until one finds the controversial topic on which scientists and engineers are busy at work” (Latour 1987, 4). The narrative device serves the sociologist well in accounting for the dynamics of science through the scientists’ own words; Janus is not committed to any representation on which a scientist (or technologist) herself would not be keen in a particular moment in time.

To make sense of science, we could easily imagine a third face of Janus, who borrows the voice of those scientists talking about the future of their fields or the emergence of new spheres of inquiry (Rheinberger 1997; Hackett 2005). Looking at the future, Janus would make promises about the fulfillment of the gaps still present in science and the grasp of what is still unknown (Borup et al. 2006). From newspapers to funding proposals, scientists spend thousands of words describing what is not yet known. Contemporary cosmologists, for example, point to the fact that they only know the constituents of 4 percent of the universe; the rest is called “dark matter,” a kind of substance still invisible to their hyper-technologized eyes (Lemonick 2013). The rainforest, in turn, has to be protected because of the huge biodiversity we still fall short of understanding; what makes it valuable, according to this kind of rhetoric, is the “undescribed and unknown” species that we still do not know but will be able to grasp in the future (Costello 2015). The agreement on what is unknown as foundational for future scientific developments has been given different names, such as “specified ignorance” in Merton (1987) or “ignorance as a native state” in Proctor (2008), but very scarce sociological attention. In fact, agreeing on what is unknown is not less of a social process than the creation of knowledge itself.

By looking at the role of the so-called shadow biosphere hypothesis in contemporary astrobiology, this paper explores how artifacts (including the entangled life of concepts and devices) are put into question in scientific discourse and everyday practices. I claim that emerging fields of inquiry presuppose one or more claims about what is still unknown, which must be agreed upon to legitimate the research and create new epistemic spaces. As a consequence, I propose that we should rethink the black-box metaphor to include more fluid, flexible, and locally contingent movements of closure and reopening. By borrowing from astrobiologists’ interest in what is in the “shadow,” I advocate paying closer attention to the ways in which claims about what is unknown are socially constructed.

A number of terms referring to claims about what is unknown can be found in Science and Technology Studies (STS) literature. In this paper, I have chosen to adopt the verb not-knowing and the nouns non-knowledge and unknown to emphasize the symmetry to knowledge (Gross 2016) and the same social nature.⁵ I follow Matthias Gross’s (2007) suggestion of adopting the term non-knowledge as a literal translation of the German Nichtwissen, indicating “a type of knowledge where the limits and the borders of knowing are taken into account for future planning and action” (p. 749). I decided not to use the term ignorance as it shares the same root of the verb to ignore, and the kind of claims I am taking into consideration are not ignored at all; they are formulated, agreed upon, and explicitly used for specific purposes. At the same time, bounding my argument to what is ignored would imply that scientists take into consideration something that was previously neglected but has always been “out there.” On the contrary, I contend that unknowns are socially constructed. In using non-knowledge and unknown, I nevertheless resist further typologies as I am intrigued by the plasticity of those non-knowledge claims; rather than encapsulate them in categories, I prefer to attend to their specificities and contingencies.

In order to do so, I find it useful in this context to consider how non-knowledge claims can be constructed and negotiated along three dimensions: awareness, intentionality, and temporality (Böschen et al. 2010). Awareness refers to something close to Donald Rumsfeld’s often-cited distinction between known unknowns—that is, things that we now know we do not know—and unknown unknowns—usually referred to as “nescience,” that is, those things we do not know we do not know; the two categories describe different epistemic phenomena. Since no one can refer to their own current nescience and thus unknown unknowns can only be realized in hindsight (when one becomes aware of them), only known unknowns can be taken into consideration from a sociological perspective (Gross 2016). The second dimension, intentionality, focuses on the effort made by social actors to tackle something that is not (yet) known. Degrees can vary from a passive lack of interest in front of what seems inconsequential non-knowledge to more active attempts to bridge salient knowledge gaps. The last dimension, temporality, refers to the stability and persistence of a non-knowledge claim and to expectations of it becoming knowable in a more or less near future. Importantly, the way a non-knowledge claim is positioned with respect to these three dimensions is not fixed once and for all. On the contrary, Böschen et al. (2010) suggest that “social conflicts over the correct assessment of what is known and not known are far from being resolved by the routine appeal to the available evidence” (p. 786). In this paper, I welcome their suggestion to investigate the pluralization of the perception and evaluation of the unknown. By focusing on the way sciences generate, define, communicate, and investigate non-knowledge in different ways, I develop the metaphor of “shadow” to move beyond the relative stability of Latour’s black-boxes and attend to unknowns-in-process (Gross 2007).

The Origin of Life Debate

In the 1860s, a young chemist, Louis Pasteur, engaged in a long and controversial debate with the naturalist Felix Pouchet over the existence of spontaneous generation, that is, the possibility that living systems could self-assemble from non-living material. Thanks to a series of experiments, Pasteur convinced the French Académie des Sciences that germs could not form inside properly sterilized flasks; when they appeared, it was simply because they were somehow introduced as a contaminant.⁶ As Latour ([1987] 1995, 2000) noted, the controversy was not simply over the spontaneous generation of microscopic living creatures in the laboratory but over the very possibility of demonstrating it. The debate was not simply about concepts but about the proper methodology and instruments to make them visible, investigable, and understandable beyond doubt. Seeking the help of Janus, one might say that if the older face (i.e., all made science) had to describe the unfolding of the controversy, he would probably say that the correct experimental method decided who was the winner of the controversy; the younger face (that of science in the making) would say that the winner was he who could convince the commission that his method was the correct one (Latour [1987] 1995). The material apparatus, constituted by flasks with different shapes, microscopes, sterilization techniques, and so on, became the very basis on which experimental biology took shape. Once the appropriateness of Pasteur’s methodology and the functioning of the laboratory as a visibility device were black-boxed, the spontaneous generation debate came to an end and the scientific community agreed on this new set of interconnected black-boxes, constituted by instruments and concepts whose social nature slowly came to be forgotten.

If the closure of the spontaneous generation debate seems to suggest that life simply does not originate from non-living matter, the inevitable observation of the existence of life on Earth presents a conundrum. In the second half of the twentieth century, the interest in the possibility of life originating from abiotic molecules cannot be encapsulated under a single disciplinary label. Among the different approaches adopted, one particular way of looking at the problem connects the study of the origin of life on Earth to the search for extra-terrestrial life elsewhere in the universe (Dick 1996; Messeri 2016). This field, once called “exobiology” and recently rebranded as “astrobiology” (Dick and Strick 2004), went through phases of hype and disappointment over the second half of the twentieth century. Astrobiology is still in the process of gaining scientific authority and being institutionalized (Des Marais et al. 2008), but its legitimacy and sustainability are often linked—today as in the past—to the questions “how likely is life to emerge?” and “what conditions are required for it to self-assemble from non-living matter?”

With very few people holding a position in between, the vast majority of those involved in the debate are divided into two factions. Those who support the so-called cosmic imperative position claim that life will promptly arise as soon as the conditions are favorable. Carl Sagan, astronomer and spokesperson for exobiology and search for extra-terrestrial intelligence (SETI) between the 1960s and the end of the 1980s, was notoriously a great supporter of this position and managed to make it very popular (see also de Duve 2011). Other authors, such as Francis Crick (1981) and Stephen Jay Gould (1989), claim that the emergence of life can only be the outcome of such an improbable chain of events that it might have happened only once in the history of the universe. These positions are both the outcome of different interpretations of the same observations, and at the same time, the very perspective from which new observations (and the appropriateness of the methodologies with whom these observations are performed) are assessed—a phenomenon known as experimenters’ regress (Collins 1985). What both factions would—at least in theory—agree on is that finding a second example of life would tip the balance in favor of a higher probability of the emergence of life (Davies 2011). This is because of the magnification factor that astronomical thinking invites: as SETI scientists often repeat, astronomers count “one, two, a billion,” alluding to the fact that if something has happened more than once, it is likely to have happened many times.

The Viking mission Press Kit, released in 1975 on the occasion of the launches of the first landers equipped with life detection experiments to be performed on the Martian surface, claimed that:

Science cannot calculate the probability of encountering extraterrestrial life on this solar system and in other solar systems on the basis of this evidence. We cannot tell conclusively by laboratory studies or theoretical reasoning whether the evolution of life is vanishingly improbable or quite likely. (p. 2)

With respect to this issue, the situation has not changed much up to the present, and—despite the wealth of estimations based on different approaches, there still seems to be no way of determining with certainty how likely the emergence of life is according to the current state of science.

The Viking Press Kit (1975) continued, “we can only estimate the probability by looking around us for signs of extra-terrestrial life; the nearest reasonable planet on which to look is Mars” (p. 2). In this respect, on the contrary, the situation has changed dramatically; after the Viking missions returned ambiguous results (Sagan, Horowitz, and Murray 1977; Young 1976), Mars had been considered for a long time a desert and inhospitable planet,⁷ and life detection experiments based on the in situ search of microbial life had, at least temporarily, been set aside. Attempts to detect the presence of extra-terrestrial life have taken different routes, the most significant of which was, in the 1970s and 1980s, the SETI⁸. Characteristic of the SETI approach is a rampant empiricism: “the probability of success is difficult to estimate,” wrote Cocconi and Morrison (1959) in their seminal work, “but if we never search the chance of success is zero” (p. 846).

In the early 2000s, a group of scientists came up with a hypothesis that could serve as a test of the two positions about the likelihood of life to emerge just relying Earth-bound research. They set out by noting the common assumption that all life on Earth shares the same ancestors, the most primitive form of life that arose, in still unknown circumstances, more than 3.5 billion years ago. All living beings on this planet, even if on different branches, are believed to belong to the same tree of life. But if life is quite likely to emerge as soon as the conditions are favorable, on Earth—the only place where we know with certainty that the conditions of life are all fulfilled—life might have originated more than once. This alternative origin of life would have given rise to a different tree of life—or maybe a number of them—that might look nothing like the tree of life we are used to, the tree of “standard” life, or life as-we-know-it. The microbiologist Shelly Copley and the philosopher Carol Cleland (2005) coined the phrase “shadow microbes” to name this parallel ecology, which, they suggest, could have been completely overlooked by traditional biology.

Life as we know it on Earth today shares a number of fundamental characteristics at the molecular level. […] However, it is also clear that some of the molecular building blocks of proteins and nucleic acids could have been different. Indeed, it is an open question as to whether all life (wherever it may be found) is constructed of proteins and nucleic acids. This question is difficult to answer outside the context of a general theory of living systems, something that we currently lack. […] The detection of even modestly different life forms poses a tremendous challenge. (Cleland 2007, 166)

Because of these unusual features, Cleland and Copley suggest, microbiologists might have never noticed these still unknown microbes, which could have gone on to evolve their own independent, interlocking ecological system or become adapted to environments that are less hospitable to familiar microbial life. In fact, if these forms of life are fundamentally different from the life to which we are used and with which we are able to interact, the tools present in the laboratory might not be able to detect or recognize them.

The Shadow Biosphere: Thinking Outside the (Black) Box

With a few excellent exceptions,⁹ sociologists of science have only very rarely taken into consideration the social processes though which, within a scientific community, non-knowledge, uncertainty, ignorance, and doubts are created; the status they acquire; and the possibilities of action that they might open (Street 2011; McGoey 2009). This could easily be due to the fact that ignorance is often simply described as a void to be filled.¹⁰

Authors such as Abbott (2010), Smithson (1985), and Proctor (2008) have proposed typologies to describe the quantity of kinds of non-knowledge, so to speak, that exist, the way they are put in place and their function. In Agnotology, Proctor (2008) proposes a threefold classification to question “the naturalness of ignorance, its causes and its distribution” (p. 3). The author describes the first kind of ignorance as a native state or as a resource; scientists, he claims, think about ignorance as a “great place to be from.” In his words,

Ignorance is seen as a resource, or at least a spur or challenge or prompt: ignorance is needed to keep the wheels of science turning. New ignorance must forever be rustled up to feed the insatiable appetite of science. […] This regenerative power of ignorance makes the scientific enterprise sustainable. We need ignorance to fuel our knowledge engines. (Proctor 2008, 4)

Proctor (2008) distinguishes this type of ignorance from other instances such as the maintenance of military secrecy or the tobacco industry’s attempts to cast doubt over the effects of smoking, which he describes as a strategic ploy or an active construct, as “something that is made, maintained, and manipulated by means of certain arts and sciences” (p. 8).¹¹ Nevertheless, as Smithson (1985, 1989) recognizes, ignorance is always socially constructed, even when it is described as a native state—the original condition of infancy or a void to be occupied by knowledge. The example of the role played by the shadow biosphere hypothesis in astrobiological research shows how non-knowledge is narrated, advocated, and negotiated in a scientific community; how it instantiates astrobiologists’ commitment to not-knowing; and how previously closed black-boxes can be reopened, unpacked, and explored.

In joining those who advocate more attention to the social production of ignorance (Croissant 2014) and its strategic deployment, I recall McGoey’s (2012) words on what she calls “antiepistemology”:

While epistemology explores the nature, methodology and limits of the production of knowledge, antiepistemology asks after its shadow: the nature of non-knowledge, and the political and social practices embedded in the effort to suppress or to kindle endless new forms of ambiguity and ignorance. (p. 3)

Actively questioning otherwise widely accepted black-boxes and borrowing astrobiologists’ interest in “what is in the shadow” can provide insight into what Gross (2007) calls unknowns-in-process. In proposing “shadow” as a metaphor to explore non-knowledge, my aim is to make explicit the situatedness and fluidity of what is unknown. “Shadow” does not refer to a property of something, but it depends on its positioning and demands that questions be asked. First and foremost, shadow of what? What kind of black-boxed artifact do the scientists want to open up, disassemble, and put into question? As black-boxes are always interconnected and built upon each other, the opening of one black-box requires a long process of unpacking that has to be followed in its intricacies and entanglements. Secondly, if a shadow is due to light, it is not simply a lack, something missing, but assumes contours and object-like qualities. The relationship between shadow and light cannot disappear, as one defines (in its etymological sense of de-finire, “putting a limit around”) the other. But one can look at the ways their boundary is pulled and pushed, moved in different directions, never to disappear. Thirdly, what is in the shadow is indeed hidden, but only partially, and thus can be represented, imagined, and used to justify research. Borrowing the metaphor of the shadow and juxtaposing it to the Latourian black-box, I thus want to emphasize the contingent, active, performative, and always social nature of the making of what is unknown.

“Alien Life, Right Under Our Noses”

Trees of Life in the Cosmic Backyard

In 2006, Paul Davies, an astrophysicist active in SETI research and self-defined “armchair astrobiologist,” (Paul Davies, personal communication, February 8, 2016) organized a workshop dedicated to “the question of how we might identify an ancient, or even extant, hidden biosphere of alien organisms.”¹² The use of the word “alien” aims to echo its Latin root alius, meaning “other” or “stranger.” Chris McKay (2013), one of the participants of the workshop and planetary scientist at NASA Ames Research Centre, commented (on a different occasion) that astrobiologists are not simply looking for life on other worlds but for “something that is not on this tree of life, an alien. When I was a kid,” he continued,

an alien was defined geographically: if you were from Mars, you were an alien; if you’re an alien, you’re from another planet. But now we define it biochemically…you can be on Earth, living right in the backyard, and be an alien if you don’t map on this tree of life. [Among the other questions], this would also tell us if life is common in the universe. If life started here in our solar system twice, independently, that would be strong evidence that life is common. (min 3.10)

The workshop’s aim was to figure out ways to look for the microbial heir of a second genesis; after describing the ways in which instruments and understandings of terrestrial life might fall short in grasping life as-we-don’t-know-it, they suggested keeping an eye open for anomalies¹³ such as signs of metabolism in conditions where life as-we-know-it would not be able to survive (e.g., at high temperature, low water availability). Felisa Wolfe-Simon—at the time a graduate student at Harvard—was among the workshop attendees, and her research at Mono Lake was inspired by those conversations (Wolfe-Simon, Davies, and Anbar 2009). In a short documentary shot during one of her fieldtrips to Mono Lake, Wolfe-Simon (2010) summarized the rationale behind her work:

I’ve come to one of the most unusual places, an alien environment here on Earth, to look for life as we don’t know it. If there is a different kind of life here on Earth, our current methods would never see it. Why? Because we only know how to look for the life we do know. So if there is a shadow biosphere, if there is an alternative kind of life, even here on Earth, we would never see it. In fact, it could be all around us. (min 5.49)

Mono Lake was taken as an example of a site that could harbor the vestiges of a shadow biosphere and a place to look for anomalies, such as microbes that could grow in conditions that would otherwise be lethal.

The intricacies of Wolfe-Simon’s unpacking of black-boxes can only be understood within the broader context that provides the social landscape of openings and closures, black-boxes, and shadows. Right after the publication of the GFAJ-1 paper in Science (and concurrently with the controversy that started on social media), Paul Davies (2010) wrote a short article on the Wall Street Journal uncovering the behind-the-scenes story of Wolfe-Simon’s research on her GFAJ-1 microbe—the name of which stands for “give Felisa a job”—and praising her bold thinking:

Felisa was still in her 20s and had a career to build. […] Most young scientists play it safe and focus on a mainstream topic. But Felisa is a free spirit with a healthy contempt for scientific and professional hierarchies, and she had faith in her hunch. She dyed her long hair a defiant bright pink and refused to be browbeaten. It was a career gamble that very few young scientists would have the courage to make.

In retrospect, this broad-minded thinking is balanced by the very pragmatic consideration that dedicating time and resources to such risky research could be inadvisable: “You cannot get a PhD out of something that doesn’t work; if you’re trying to culture some sort of bacteria or some sort of microbe in the lab…and it won’t grow, your first thought is ‘I’d better find something else, I’d better do a different experiment and find a different microbe’ (Personal communication, February 8, 2016).” Being a good microbiologist, and thus obtaining a doctorate or having your research funded, often means making use of and aligning with a series of black-boxes accepted as foundational of empirical biology and thus normatively regulating what shall be considered appropriate within that disciplinary framework. The evaluation of the outcome of an experiment (and whether the experiment itself counts as successful) can be based on compliance with these black-boxes¹⁴—but not necessarily (Benner, Bains, and Seager 2013; Jogalekar 2013, 2015). What counts as properly scientific depends on the context and might be based on the attribution of diametrically opposed characteristics (Gieryn 1983; Mulkay and Gilbert 1982). Pursuing what is unlikely, counterintuitive, and yet logically acceptable becomes, in the search for life in the universe (and on Earth) the seal of scientificity, of an empiricism that—like SETI—reclaims the right to look and search for anomalies even in spite of mainstream theories, which from this perspective resemble doctrine more than reason.

In fact, despite the debacle described in the incipit of this paper, it would be misleading to say that the GFAJ-1 case was not successful, at least in part. A number of laboratories tried to replicate Wolfe-Simon’s experiments and look into the matter further, and they used blogs to make the results immediately available. Although most microbiologists immediately attempted to re-close what Wolfe-Simon, Davies, and others had tried to open up for scrutiny, for the astrobiology community, the right to keep on looking for anomalies in an attempt to shed light on the unknown nature of alien life had proven to be a strategically deployable narrative. GFAJ-1 messed things up, created shadows, moved them around, and situated knowledge and non-knowledge in space (claiming that current theories about life might hold on this planet only) and time (renegotiating what was known, what was not-known, and the temporal horizon for them to become knowable). Astrobiology is gaining momentum, not only due to uncontroversial discoveries and widely accepted protocols but also because of the taking shape of what should not be taken for granted anymore.¹⁵ Being a good astrobiologist—and making astrobiology a respectable discipline in the first place—requires that scientists learn how to question the rigidity of otherwise widely accepted claims and the very instruments in which these principles are inscribed. Thinking about the possibility that some forms of life might live undisturbed and unseen requires astrobiologists to open the black-boxes that Pasteur and his colleagues already closed: those of sterilization, culture, and the possibility of determining whether those techniques were performed successfully. Once they are reopened, the inability of life to self-assemble, to spontaneously emerge out of non-life, is put into question and thus biology is made partial, local, and biased by Earthly idiosyncrasies.

Uncertain laboratories, emerging sciences: Making microbes invisible again

When I asked astrobiologists what their laboratories looked like, I was often told that they completely resembled any other microbiology lab but that all the activities were performed with a context in mind. To figure out what this context might consist of, I spent many mornings strolling around an astrobiology lab. Sitting on the stool in front of the microscope, one day, one of the senior PhD students in astrobiology was looking at his microbial samples. Leaning on the microscope ocular, the young researcher zoomed in on random spots of the slide he had carefully prepared and counted the cells lightened in every spot to estimate their growth or ratio of survival. “How many cells are there?” I asked. “Not that many of them,” he replied, and then he explained that most of them had probably died, at least those that we know. But that thin piece of glass might have held plenty of cells from a shadow biosphere, he explained, that he simply could not see or recognize: “…alien life right under our noses.” His younger colleague, pipetting on the nearby bench, turned his head around and asked what he was talking about. “It’s just a hypothesis,” he replied, shrugging his shoulders, “but it makes you wonder…!” In fact, as mentioned above, very little research into the shadow biosphere hypothesis is today actively carried out in laboratories, possibly as a side effect of the harsh debacle that followed NASA’s triumphant announcement. The shadow biosphere hypothesis, which became both well-known and infamous following Wolfe-Simon’s GFAJ-1 article, did not fade: on the contrary, the possible existence of a shadow biosphere, even if seldom discussed in formal settings, is still brought up in informal talks and taken into consideration when debating whether anomalies should be discarded as failed experiments or investigated as possible insights into what “traditional” biology would fail to grasp.

Inside the laboratory walls, the detection and recognition of microbial life forms is mediated by a multitude of instruments that make them visible and manipulable. The simple act of looking is more troublesome that one can imagine. First of all, the microbes the scientist was interested in did not come from a commercial strain; they were not purchased from an online catalog and delivered to the lab but instead collected on a field site, in some environment presenting characteristics of interest as analogue to other planetary places. Immediately after collection, the samples were stored in plastic bags and then carried to the laboratory where microbes could be separated from other components of the sample. Extracting microbes from a soil sample requires a complex mix of crushing, dissolving, blending, and centrifuging. Once separated, they can be transferred on to agar plates and cultured in different conditions for several days to monitor their responses.

Cell culture is used to make microbes visible by causing them to grow into large communities. Biologists spend a significant part of their time taking care of their cultures, following protocols for “optimal” growth. However, they are adamant that only a small portion—less than 1 percent, according to Pace (1997)—of the huge microbial diversity found in the field can be cultured in the lab, often for unknown reasons. The identity of most of the microbes refusing to survive and duplicate within a petri dish remains unknown, “shrugged aside as uncooperative” (Davies et al. 2009, 247). Shadow life forms might require conditions that astrobiologists do not expect, for example, unusual chemical elements, extreme temperatures, and a different barometric pressure putting into perspective adjectives such as “standard,” “normal,” and “optimal” (Helmreich 2012).

An important technique for identifying unculturable components of microbial communities is polymerase chain reaction (PCR), which allows the amplification of a segment of DNA across several orders of magnitude. However, PCR might not be serviceable for different forms of life, as the process requires “universal primers,” which might in fact turn out to be very specific and contingent.

The microscope allows the researcher to exercise her sensing capabilities across scales with the mediation of lenses, lights, dyes, calibrations, and so on. Nevertheless, under the lens of a microscope, single cells with a structure different from what scientists are used to might not be visible, as fluorescent microscopy can only identify cells containing a gene or protein complementary to the probe being used. On the contrary, they might be visible (if they contain sites where the dye can attach or with traditional optical microscopes) but not recognizable, as the morphology of microbes (i.e., their shape and physical characteristics) provides little insight into their phylogenetic classification or metabolic capabilities. As Cleland and Copley (2005) put it, “we are unlikely to be able to distinguish between normal life and alternative life just by looking” (p. 168).

Each of these devices is a black-box connected to all the others that come to constitute a microbiology lab. These techniques, when thought about in relation to the hypothesis of the existence of an independent biosphere, have to be reopened. Despite—and because of—the heuristic uncertainty, they offer a handhold for astrobiologists’ commitment to unknowns and help to articulate questions that might not otherwise have made sense. The idea of a shadow biosphere is a discursive space in which astrobiologists can share their perplexities, uncertainties, and new possibilities of visualizing living beings and broadening the definition of life. It goes hand-in-hand and reinforces the idea that life and its kaleidoscope of possibilities remains unknown and in need of a new approach for further investigation. This set of uncertainties and unknowns is, in a sense, the different context that astrobiologists have in mind when performing their daily work at the laboratory bench. In Davies and colleagues’ (2009) words:

This extensive ignorance raises the intriguing issue of how sure we can be that all microbial types have been identified. Might it be the case that the exploration of the biosphere is not complete? (p. 421)

We can easily imagine the third face of Janus pronouncing this sentence, using the astrobiologists’ questioning of the heuristic power of the laboratory instruments to open up and look inside a number of interconnected black-boxes. In so doing, they agree on what might be still in the shadows—unobserved and unacknowledged—and thus tweak instruments, concepts, and procedure toward the creation of a new epistemic space in which new research questions can become relevant and be investigated. By emphasizing its locality and idiosyncrasy (Dick and Strick 2004), these unknowns contribute to the displacement of biology from the place it occupies in the scientific landscape and offers a fertile terrain to advocate what astrobiologists propose as a more “universal” biology.

Conclusion

In this paper, I take the emergence of the so-called shadow biosphere hypothesis and the controversial discovery of GFAJ-1, a microbe thriving in the arsenic-rich waters of Mono Lake, as an entry point to look into the strategic role of non-knowledge claims. On the one hand, the possibility of pleading against the successful use of instruments by means of which living organisms are known and made recognizable offered astrobiologists the opportunity to propose new sites and methodologies for life detection. To think differently, astrobiologists have to displace their research outside the traditional biological bench or make the laboratory walls permeable to other ways of asking questions about life, for example, by moving their instruments to the field—where they might not work as efficiently as in the controlled environment of the laboratory—and look for anomalies. On the other hand, the shadow biosphere hypothesis reinforces the agreement on another significant non-knowledge claim that characterizes astrobiology: the fact that we still do not know what life.

Importantly, I have shown how, despite their reference to traditional biology¹⁶ as a paradigm to be overcome by astrobiology, explicitly highlighting the necessary attention to anomalies, astrobiologists’ unpacking of the microbial black-boxes is indeed partial, as they continue to capitalize on the assumptions embedded in most of the black-boxes they question for other practical needs, for example, publishing papers with data obtained in the laboratory (with all its “traditional” techniques), elaborating experiments and measurements and seeking collaborations with microbiologists, synthetic biologists, and so on. A black-box, then, can be both sealed within a certain disciplinary framework and partially opened in different epistemic contexts. Openings and closures should not be considered as finished actions but have to be understood as flexible and locally contingent processes. Researchers can and do shift between different approaches and models of work (Ankeny and Leonelli 2016), depending on circumstances; they can make use of traditional biology’s black-boxes, perhaps without even realizing it, but at the same time unpack them and look into their functioning, give shape to new unknowns, and deploy them strategically.

It is because of this contextual and always situated assessment of what can and should be taken for granted, and the consequent agreement on what is known, unknown, and knowable, that the opening of black-boxes is instrumental to the endorsement of new spheres of inquiry. If successfully negotiated, this newly created knowledge gaps contribute to the positioning of emerging fields of research within the larger scientific community.

By juxtaposing the Latourian black-box, that is, those undiscussed technoscientific artifacts that are taken for granted in scientific practice, with the shadowy nature of non-knowledge claims, I advocate paying closer attention to the contingent, active, performative, and always social nature of the making of what is unknown. Unknowns are not a negative and unavoidable aspect of scientific research. On the contrary, they are fundamental resources actively shaped and mobilized in discourse and practice. The deployment of “shadow” as a metaphor to look into the specificities of non-knowledge allows a deeper insight into the continuities and discontinuities inherent in scientific change.

Footnotes

Acknowledgments

I wish to thank Jane Calvert and Alice Street for their precious help and Giampietro Gobo for his tireless support. I would also like to express my most sincere gratitude to Rodolfo John Alaniz, Elizabeth Petrick, Caitlin Wylie, and to the two anonymous reviewers for thoughtful comments on the article.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Valentina Marcheselli

Notes

References

Abbott

Andrew

. 2010. “Varieties of Ignorance.” The American Sociologist 41 (2): 174–89.

Ankeny

Rachel A.

Leonelli

Sabina

. 2016. “Repertoires: A Post-Kuhnian Perspective on Scientific Change and Collaborative Research.” Studies in History and Philosophy of Science 60 (2016): 18–28.

Beck

Ulrich

. (1986) 1992. Risk Society. Towards a New Modernity. Translated by Ritter

Mark

. Los Angeles, CA: Sage.

Benner

Steven A.

Bains

William

Seager

Sara

. 2013. “Models and Standards of Proof in Cross-disciplinary Science: The Case of Arsenic DNA.” Astrobiology 13(5): 510–13.

Borup

Mads

Brown

Nik

Konrad

Kornelia

Lente

Harro van

. 2006. “The Sociology of Expectations in Science and Technology.” Technology Analysis & Strategic Management 18 (3/4): 285–98.

Böschen

Stefan

Kastenhofer

Karen

Rust

Ina

Soentgen

Jens

Wehling

Peter

. 2010. “Scientific Nonknowledge and Its Political Dynamics: The Cases of Agri-biotechnology and Mobile Phoning.” Science, Technology, & Human Values 35 (6): 783–811.

Cleland

Carol

. 2007. “Epistemological Issues in the Study of Microbial Life: Alternative Terran Biospheres?” Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences 38 (4): 847–61.

Cleland

Carol

Copley

Shelly

. 2005. “The Possibility of Alternative Microbial Life on Earth.” International Journal of Astrobiology 4 (3-4): 165–73.

Cocconi

Giuseppe

Morrison

Philip

. 1959. “Searching for Interstellar Communications.” Nature 184 (4690): 844–46.

10.

Collins

Harry

. 1985. Changing Order: Replication and Induction in Scientific Practice. London, UK: Sage.

11.

Costello

Mark J.

2015. “Biodiversity: The Known, Unknown, and Rates of Extinction.” Current Biology 25 (9): R368–71.

12.

Cressey

Daniel

. 2012. “‘Arsenic-life’ Bacterium Prefers Phosphorus After All.” Nature News, October 3. Accessed March 15, 2018. https://www-nature-com-s.web.bisu.edu.cn/news/arsenic-life-bacterium-prefers-phosphorus-after-all-1.11520.

13.

Crick

Francis

. 1981. Life Itself. Its Origin and Nature. New York: Simon & Schuster.

14.

Croissant

Jennifer

. 2014. “Agnotology: Ignorance and Absence or towards a Sociology of Things That Aren’t There.” Social Epistemology 28 (1): 4–25.

15.

Davies

Paul

. 2010. “The ‘Give Me a Job’ Microbe. A Young Researcher Risked It All to Chase an Arsenic-guzzling Bug.” Wall Street Journal, December 4. Accessed March 15, 2018. https://www.nytimes.com/2010/12/14/science/14arsenic.html.

16.

Davies

Paul

. 2011. “Searching for a Shadow Biosphere on Earth as a Test of the ‘Cosmic Imperative’.” Philosophical Transactions. Series A, Mathematical, Physical and Engineering Sciences 369 (1936): 624–32.

17.

Davies

Paul

Benner

S. A.

Cleland

C. E.

Lineweaver

C. H.

McKay

C. P.

Wolfe-Simon

. 2009. “Signatures of a Shadow Biosphere.” Astrobiology 9 (2): 241–49.

18.

de Duve

Christian

. 2011. “Life as a Cosmic Imperative?” Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369 (2011): 620–23.

19.

Des Marais

David

Nuth

Joseph A.

Allamandola

Louis J.

Boss

Alan P.

Farmer

Jack D.

Hoehler

Tori M.

Jakosky

Bruce M.

. 2008. “The NASA Astrobiology Roadmap.” Astrobiology 8 (4): 715–30.

20.

Dick

Stephen

. 1996. The Biological Universe. The Twentieth-century Extraterrestrial Life Debate and The Limits of Science. Cambridge, MA: Cambridge University Press.

21.

Dick

Steven J.

Strick

James E.

. 2004. The Living Universe. NASA and the Development of Astrobiology. New Brunswick, NJ: Rutgers University Press.

22.

Farley

John

Geison

Gerald

. 1974. “Science, Politics and Spontaneous Generation in Nineteenth Century France: The Pasteur-Pouchet Debate.” Bulletin of the History of Medicine 48 (2): 161–98.

23.

Galison

Peter

. 2010. “Secrecy in Three Acts.” Social Research 77 (3): 941–74.

24.

Giddens

Anthony

. 1990. The Consequences of Modernity. Stanford, CA: Stanford University Press.

25.

Gieryn

Thomas

. 1983. “Boundary-work and the Demarcation of Science from Non-science: Strains and Interests in Professional Ideologies of Scientists.” American Sociological Review 48 (6): 781–95.

26.

Gould

Stephen J.

1989. Wonderful Life: The Burgess Shale and the Nature of History. New York: W. W. Norton.

27.

Gross

Matthias

. 2007. “The Unknown in Process: Dynamic Connections of Ignorance, Non-knowledge and Related Concepts.” Current Sociology 55 (5): 742–59.

28.

Gross

Matthias

. 2016. “Risk as Zombie Category: Ulrich Beck’s Unfinished Project of the ‘Non-knowledge’ Society.” Security Dialogue 47 (5): 386–402.

29.

Hackett

Edward J.

2005. “Essential Tensions. Identity, Control and Risk in Research.” Social Studies of Science 35 (5): 787–826.

30.

Hayden

Erika

. 2012. “Study Challenges Existence of Arsenic-based Life. Open-science Advocates Fail to Reproduce Controversial Findings.” Nature News, January 20. Accessed October 3, 2019. https://www-nature-com-s.web.bisu.edu.cn/news/study-challenges-existence-of-arsenic-based-life-1.9861.

31.

Helmreich

Stefan

. 2012. “Extraterrestrial relativism.” Anthropological Quarterly 85 (4): 1125–39.

32.

Jogalekar

Ashutosh

. 2013. “Arsenic DNA, Chemistry and the Problem of Differing Standards of Proof in Cross-disciplinary Science.” Scientific American, October 22. Accessed October 3, 2019. https://blogs.scientificamerican.com/the-curious-wavefunction/arsenic-dna-chemistry-and-the-problem-of-differing-standards-of-proof-in-cross-disciplinary-science/.

33.

Jogalekar

Ashutosh

. 2015. “Social Media, Peer Review, and Responsible Conduct of Research (RCR) in Chemistry: Trends, Pitfalls, and Promises.” Accountability in Research 22 (6): 402–30.

34.

Knorr-Cetina

Karin

. 1999. Epistemic Cultures: How the Sciences Make Knowledge. Cambridge, UK: Harvard University Press.

35.

Kuhn

Thomas

. 1962. The Structure of Scientific Revolutions. Chicago: University of Chicago Press.

36.

Latour

Bruno

. 1987. Science in Action, How to Follow Scientists and Engineers through Society. Milton Keynes, UK: Open University Press.

37.

Latour

Bruno

. [1987] 1995. “Pasteur-Pouchet, the Heterogenesis of the History of Science.” In A History of Scientific Thought. Elements of a History of Science, edited by Serres

Michel

, 526–55. Oxford, UK: Blackwell.

38.

Latour

Bruno

. 2000. “On the Partial Existence of Existing and Nonexisting Objects.” In Biographies of Scientific Objects, edited by Daston

Lorraine

, 247–69. Chicago: Chicago University Press.

39.

Lemonick

Michael

. 2013. “Telescope to Hunt for Missing 96% of the Universe.” Times Magazine, February 20. Accessed March 15, 2018. http://science.time.com/2013/02/20/telescope-to-hunt-for-missing-96-of-the-universe/.

40.

McGoey

Linsey

. 2009. “Pharmaceutical Controversies and the Performative Value of Uncertainty.” Science as Culture 18 (2): 151–64.

41.

McGoey

Linsey

. 2012. “Strategic Unknowns: Towards a Sociology of Ignorance.” Economy and Society 41 (1): 1–16.

42.

McKay

Christopher

. 2013. Life beyond the Earth. Accessed October 3, 2019. https://www.youtube.com/watch?v=VHJRUYk3cHE&t=196s.

43.

Merton

Robert

. 1987. “Three Fragments from a Sociologist’s Notebooks: Establishing the Phenomenon, Specified Ignorance, and Strategic Research Materials.” Annual Review of Sociology 12 (1987): 1–28.

44.

Messeri

Lisa

. 2016. Placing Outer Space: An Earthly Ethnography of Other Worlds. Durham, NC: Duke University Press.

45.

Michaels

David

. 2008. Doubt Is Their Product: How Industry’s Assault on Science Threatens Your Health. New York: Oxford University Press.

46.

Mulkay

Michael

Gilbert

Nigel

. 1982. “Accounting for Error: How Scientists Construct Their Social World When They Account for Correct and Incorrect Belief.” Sociology 16 (2): 165–83.

47.

Oremland

Ronald

Saltikov

Chad W.

Wolfe-Simon

Felisa

Stolz

John

. 2009. “Arsenic in the Evolution of Earth and Extraterrestrial Ecosystems.” Geomicrobiology Journal 26 (7): 522–36.

48.

Oreskes

Naomi

Conway

Erik M.

. 2010. Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming. New York: Bloomsbury Press.

49.

Pace

Norman R.

1997. “A Molecular View of Microbial Diversity and the Biosphere.” Science 274 (1997): 734–40.

50.

Proctor

Robert

. 2008. “Agnotology: A Missing Term to Describe the Cultural Production of Ignorance.” In Agnotology: The Making and Unmaking of Ignorance, edited by Proctor

Schiebinger

, 1–36. Stanford, CA: Stanford University Press.

51.

Redfield

Rosie

. 2010. “Arsenic-associated Bacteria (NASA’s Claims).” RRResearch, December 4. Accessed March 15, 2018. http://rrresearch.fieldofscience.com/2010/12/arsenic-associated-bacteria-nasas.html.

52.

Rheinberger

Hans-Jorg

. 1997. Toward a History of Epistemic Things: Synthesizing Proteins in the Test Tube. Stanford, CA: Stanford University Press.

53.

Roll-Hansen

Neil

. 1979. “Experimental Method and Spontaneous Generation: The Controversy between Pasteur and Pouchet, 1959-64.” Journal of the History of Medicine and Allied Sciences 34 (3): 273–92.

54.

Sagan

Carl

Horowitz

Norman

Murray

Bruce

. 1977. “Continuing Puzzles about Mars.” Bulletin of the American Academy of Arts and Sciences 30 (7): 10–31.

55.

Seager

Sara

. 2013. “Exoplanet Habitability.” Science 340 (6132): 577–81.

56.

Smithson

Michael

. 1985. “Toward a Social Theory of Ignorance.” Journal of the Theory of Social Behaviour 15 (2): 151–72.

57.

Smithson

Michael

. 1989. Ignorance and Uncertainty: Emerging Paradigms. New York: Springer-Verlag.

58.

Steele

Goddard

D. T.

Stapleton

Toporski

J. K. W.

Peters

Bassinger

Sharples

Wynn-Williams

D. D.

McKay

D. S.

. 2000. “Investigations into an Unknown Organism on the Martian Meteorite Allan Hills 84001.” Meteoritics and Planetary Science 35 (2): 273–41.

59.

Street

Alice

. 2011. “Artefacts of Non-knowing: The Medical Record, the Diagnosis and the Production of Uncertainty in Papua New Guinean Biomedicine.” Social Studies of Science 41 (6): 815–34.

60.

Viking Press Kit. 1975. Viking Press Kit. (February). Accessed March 15, 2018. https://mars.nasa.gov/msl/newsroom/presskits/viking.pdf.

61.

Walker

Sarah

. 2017. “Origins of Life: A Problem for Physics. A Key Issues Review.” Report on the Progress in Physics 80 (9): 092601.

62.

Wolfe-Simon

Felisa

. 2010. NASA News Conference on Astrobiology Discovery. December 2. Accessed March 15, 2018. https://www.youtube.com/watch?v=WVuhBt03z8g.

63.

Wolfe-Simon

Felisa

Blum

Jodi

Kulp

Thomas

Gordon

Gwyneth

Hoeft

Shelley

Pett-Ridge

Jennifer

Stolz

John

, et al. 2011. “A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus.” Science 332 (6034): 1163–67.

64.

Wolfe-Simon

Felisa

Davies

Paul C. W.

Anbar

Ariel D.

. 2009. “Did Nature Also Choose Arsenic?” International Journal of Astrobiology 8 (2): 69–74.

65.

Young

Richard

. 1976. “Viking on Mars, a Preliminary Survey.” American Scientist 64 (6): 620–27.