This book focuses on the emerging scientific discipline of astrobiology, exploring the humanistic issues of this multidisciplinary field. To be sure, there are myriad scientific questions that astrobiologists have only begun to address. However, this is not a purely scientific enterprise. More research on the broader social and conceptual aspects of astrobiology is needed. Just what are our ethical obligations toward different sorts of alien life? Should we attempt to communicate with life beyond our planet? What is “life” in (...) the most general sense? The current volume addresses these questions by looking at different perspectives from philosophers, historians, theologians, social scientists, and legal scholars. It sets a benchmark for future work in astrobiology, giving readers the groundwork from which to base the continuous scholarship coming from this ever-growing scientific field. (shrink)

Astrobiologists are aware that extraterrestrial life might differ from known life, and considerable thought has been given to possible signatures associated with weird forms of life on other planets. So far, however, very little attention has been paid to the possibility that our own planet might also host communities of weird life. If life arises readily in Earth-like conditions, as many astrobiologists contend, then it may well have formed many times on Earth itself, which raises the question whether (...) one or more shadow biospheres have existed in the past or still exist today. In this paper, we discuss possible signatures of weird life and outline some simple strategies for seeking evidence of a shadow biosphere. Key Words: Weird life—Multiple origins of life—Biogenesis—Biomarkers—Extremophiles—Alternative biochemistry. Astrobiology 9, 241–249. (shrink)

To date, no definition of life has been unequivocally accepted by the scientific community. In frustration, some authors advocate alternatives to standard definitions. These include using a list of characteristic features, focusing on life’s effects, or categorizing biospheres rather than life itself; treating life as a fuzzy category, a process or a cluster of contingent properties; or advocating a ‘wait-and-see’ approach until other examples of life are created or discovered. But these skeptical, operational, and pluralistic approaches have intensified the debate, (...) rather than settled it. Given the failure of even these approaches, we advocate a new strategy. In this paper, we reverse the usual line of reasoning and argue that the “life problem” arises from thinking incorrectly about the nature of life. Scientists most often conceptualize life as a class or kind, with earthly life as a single instance of it. Instead, we advocate thinking about Earth’s Life as an individual, in the way that species are now thought to be. In this view, Life is a monophyletic clade that originated with a last universal common ancestor, and includes all its descendants. We can continue to use the category ‘life’ pragmatically to refer to similarities between various phenomena and Life. But the relevant similarities are a matter of interest and preference, not a matter of fact. The search for other life in the Universe, then, is merely a search for entities that resemble parts of Life in whatever sense astrobiologists find most appealing. This does not mean that the search for evolved complexity elsewhere in the universe or its creation in the lab are futile endeavors, but that debates over whether they count as ‘life’ are. Ironically, finally abandoning the concept ‘life’ may make our searches for evolved complexity more fruitful. We explain why. (shrink)

This Special Issue of Origins of Life and Evolution of Biospheres contains papers based on the contributions presented at the Conference "Defining Life" held in Paris (France) on 4-5 February, 2008. The main objective of this Conference was to confront speakers from several disciplines--chemists, biochemists, biologists, exo/astrobiologists, computer scientists, philosophers and historians of science--on the topic of the definition of life. Different viewpoints of the problem approached from different perspectives have been expounded and, as a result, common grounds as (...) well as remaining diverging arguments have been identified. In addition to individual talks, two large roundtables gave ample room for speakers to discuss their diverging viewpoints. This volume collects almost all the contributions presented during the Conference and provides a rich spectrum of renewed answers to the ever-standing question "What is Life?". Besides the arguments directly regarding this question, more philosophical or historical reflections are also proposed in this issue that were not presented during the Conference. This volume also offers a synthesis written by J. Gayon taking each contribution into account. To conclude this foreword, we would like to thank all the participants and speakers who made this Conference a most stimulating event. Each provided novel ideas to "Defining Life" while highlighting the extreme difficulty to reach a consensus on this topic. We are also very grateful to the French CNRS Interdisciplinary Program Origines des Planètes et de la Vie (Origins of Planets and Life) for its generous support, as well as to the National Museum of Natural History in Paris for hosting the Conference. We also thank Alan W. Schwartz for generously offering this space for publishing the Proceedings of the Conference. (shrink)

As we envision constructive undertakings in the field of religion and science for the next decade, the emerging agenda of astrotheology is opening up a new theater for enquiry. Astrotheology provides a critical theological response to the field of astrobiology while critically assessing exciting new research on life in our solar system and the discovery of exoplanets. This article proposes four tasks for the astrotheologian: deliberate on (1) the scope of creation: is God's creation Earth-centric or does it include the (...) entire cosmos? (2) the question whether a single divine incarnation on Earth suffices for the cosmos or whether multiple incarnations—one for each inhabited planet—is required; (3) whether astrobiologists and other space scientists are sticking to their science or smuggling in ideology; and (4) readying terrestrial life for contact with extraterrestrial life by enumerating issues to be taken up by astroethics. (shrink)

While the scientific discourse on astrobiology—the study of the origin, evolution, and distribution of life in the universe—leans toward optimism about the possibility of extraterrestrial life, optimistic thinking is tempered by the limits of evidence and observations gathered thus far. Most astrobiologists assume that “first contact” with extraterrestrial life, if it is ever to occur, will likely be the discovery of microbial life elsewhere in our solar system. But in popular culture, “first contact” tends to be characterized as contact (...) with extraterrestrial intelligence. This article will touch on theory and research relating to the origins and evolution of life and intelligence on Earth and speculation about extraterrestrial life and intelligence. (shrink)

For decades most scientists assumed that life emerged billions of years ago in a “primordial soup” somewhere on the Earth’s surface. Evidence is mounting, however, that life may have begun deep beneath the surface, perhaps near a volcanic ocean vent or even inside the hot crust itself. Since there are hints that life’s history on Earth extends back through the phase of massive cosmic bombardment, it may be that life started on Mars and came here later, perhaps inside rocks ejected (...) from the Red Planet by large impacts. The traffic of intact rocks between Mars and Earth is now an established fact, and experiments confirm that microbes could survive the rigours of the journey through space if cocooned within such material. Unfortunately, this planetary cross- contamination compromises astrobiologists’ hope of finding a second genesis in the solar system. (shrink)

Astrobiology aims to determine the distribution and diversity of life in the universe. But as the word “biosignature” suggests, what will be detected is not life itself, but an observation implicating living systems. Our limited access to other worlds suggests this observation is more likely to reflect out‐of‐equilibrium gasses than a writhing octopus. Yet, anything short of a writhing octopus will raise skepticism about what has been detected. Resolving that skepticism requires a theory to delineate processes due to life and (...) those due to abiotic mechanisms. This poses an existential question for life detection: How do astrobiologists plan to detect life on exoplanets via features shared between non‐living and living systems? We argue that you cannot without an underlying theory of life. We illustrate this by analyzing the hypothetical detection of an “Earth 2.0” exoplanet. Without a theory of life, we argue the community should focus on identifying unambiguous features of life via four areas: examining life on Earth, building life in the lab, probing the solar system, and searching for technosignatures. Ultimately, we ask, what exactly do astrobiologists hope to learn by searching for life? (shrink)

This book aims at providing a brief but broad overview of biosignatures. The topics addressed range from prebiotic signatures in extraterrestrial materials to the signatures characterising extant life as well as fossilised life, biosignatures related to space, and space flight instrumentation to detect biosignatures either in situ or from orbit. The book ends with philosophical reflections on the implications of life elsewhere. In the 15 chapters written by an interdisciplinary team of experts, it provides both detailed explanations on the nature (...) of biosignatures as well as useful case studies showing how they are used and identified in ancient rocks, for example. One case study addresses the controversial finding of traces of fossil life in a meteorite from Mars. The book will be of interest not only to astrobiologists but also to terrestrial paleontologists as well as any reader interested in the prospects of finding a second example of life on another planet. (shrink)

The problem of life’s origin remains one of the great outstanding challenges to science. Ever since Charles Darwin mused about a “warm little pond” incubating life beneath sunny primeval skies, scientists have speculated about the exact location of this transforming event. Nearly a century and a half later, we remain almost completely ignorant of the physical processes that led from a nonliving chemical mixture to the first autonomous organism. However, some progress at least has been made on tracking down where (...) and when life first established itself on Earth. Fossil evidence suggests that the biological record extends back at least 3.5 billion years, pointing to a still earlier origin1. But this presents a problem. The cratering record of the moon implies that Earth was subjected to intense bombardment by large comets and asteroids over an extended duration until about 3.8 billion years ago. The largest of these impacts would have released enough energy to swathe the planet in incandescent rock vapour, boiling the oceans and sending sterilizing heat pulses a kilometre into the exposed crust2. This unpromising setting – hardly a secure one for warm little ponds – has prompted some astrobiologists to conjecture that life began somewhere else and came to Earth readymade3. Favourite among extraterrestrial originating locations is the planet Mars4. (shrink)

How far apart are humans from animals—even the “vampire squid from hell”? Playing the scientist/philosopher/provocateur, Vilém Flusser uses this question as a springboard to dive into a literal and a philosophical ocean. “The abyss that separates us” from the vampire squid “is incomparably smaller than that which separates us from extraterrestrial life, as imagined in science fiction and sought by astrobiologists,” Flusser notes at the outset of the expedition. Part scientific treatise, part spoof, part philosophical discourse, part fable, _Vampyroteuthis (...) Infernalis_ gives its author ample room to ruminate on human—and nonhuman—life. Considering the human condition along with the vampire squid/octopus condition seems appropriate because “we are both products of an absurd coincidence... we are poorly programmed beings full of defects,” Flusser writes. Among other things, “we are both banished from much of life’s domain: it into the abyss, we onto the surfaces of the continents. We have both lost our original home, the beach, and we both live in constrained conditions.” Thinking afresh about the life of an “other”—as different from ourselves as the vampire squid/octopus—complicates the linkages between animality and embodiment. Odd, and strangely compelling, _Vampyroteuthis Infernalis_ offers up a unique posthumanist philosophical understanding of phenomenology and opens the way for a non-philosophy of life. (shrink)

Here I pursue a deconstructive reading of astrobiology, the emerging science dedicated to a double quest: solving the mystery of life's origin and discovering life beyond Earth. Astrobiology, I argue, is organized as a response to the aporetic formulation assumed by the origin of life in modern molecular biology, where (as Derrida's argues in Life Death) it becomes the origin of textuality. Because all Earth life shares a single genetic code, astrobiologists are seeking a second; hoping that a sort (...) of multi-planetary comparative genomics may reveal the secret to life's origin. But the aporia repeats in the figure of the biosignature, the trace of life. (shrink)

The interdisciplinary field of astrobiology constitutes a joint arena where provocative discoveries are coalescing concerning, e.g. the prevalence of exoplanets, the diversity and hardiness of life, and its chances for emergence. Biologists, astrophysicists, (bio)-chemists, geoscientists and space scientists share this exciting mission of revealing the origin and commonality of life in the Universe. With its overview articles and its definitions the Encyclopedia of Astrobiology not only provides a common language and understanding for the members of the different disciplines but also (...) serves for educating a new generation of young astrobiologists who are no longer separated by the jargon of individual scientific disciplines. -/- This new edition offers ~170 new entries. More than half of the existing entries were updated, expanded or supplemented with figures supporting the understanding of the text. Especially in the fields of astrochemistry and terrestrial extremophiles but also in exoplanets and space sciences in general there is a huge body of new results that have been taken into account in this new edition. (shrink)

This is a digest of how various researchers in biology and astrobiology have explored questions of what defines living organisms—definitions based on functions or structures observed in organisms, or on systems terms, or on mathematical conceptions like closure, chirality, quantum mechanics and thermodynamics, or on biosemiotics, or on Darwinian evolution—to clarify the field and make it easier for endeavors in artificial intelligence to make progress. Current ideas are described to promote work between astrobiologists and computer scientists, each concerned with (...) living organisms. A four-parameter framework is presented as a scaffold that is later developed into what machines lack to be considered alive: systems, evolution, energy and consciousness, and includes Jagers operators and the idea of dual closure. A novel definition of consciousness is developed which describes mental objects both with and without communicable properties, and this helps to clarify how consciousness in machines may be studied as an emergent process related to choice functions in systems. A perspective on how quantization, acting on nucleic acids, sets up natural limits to system behavior is offered as a partial address to the problem of biogenesis. (shrink)

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. (shrink)