What is Life? On Earth and Beyond

Chapter Abstracts

Approaches from the sciences, philosophy and theology, including the emerging field of astrobiology, can provide fresh perspectives to the age-old question 'What is Life?'. Has the secret of life been unveiled and is it nothing more than physical chemistry? Modern philosophers will ask if we can even define life at all, as we still don't know much about its origins here on Earth. Others regard life as something that cannot simply be reduced to just physics and chemistry, while biologists emphasize the historical component intrinsic to life on Earth. How can theology constructively interpret scientific findings? Can it contribute constructively to scientific discussions? Written for a broad interdisciplinary audience, this probing volume discusses life, intelligence and more against the background of contemporary biology and the wider contexts of astrobiology and cosmology. It also considers the challenging implications for science and theology if extraterrestrial life is discovered in the future.

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Kathrin Altwegg


Andreas Losch



Marie-Christine Maurel

Reflections on the Origins, Life, and the Origins of Life

The term origin has at least two meanings: (1) that which is located at the origin, at the beginnings; and (2) that which is the basis, the foundation on which something is grounded. What do we know about the origins of life? Does a plan exist concerning the basis of the origins? Can one think of the occurrence of biological entities as the artisan thinks of his own project, his own plan? Science demonstrates that things are not a Kantian thing-in-itself, and most current theories on the origins of life propose that organic molecules present on the early Earth became the raw material from which biological systems developed. This chapter presents some general epistemological reflections, then summarizes the current understanding of the conditions that led to macromolecules from simple monomers abiotically synthesized that led to some of the earliest chemical steps from which the basic metabolic steps first appeared. A model is proposed for the development of replicative systems from random polymers that evolved through mutation and selection. One can say that the origin of life marks the start of biological evolution.


Joshua Krissansen-Totton and David C. Catling

The Search for another Earth-like Planet and Life elsewhere

In the coming decades, life could be discovered on exoplanets – planets around other stars – using telescopes. This chapter explores the science behind such a remarkable prediction. Progress in astronomy has led to the discovery of thousands of exoplanets. Telescopic data can be used not only to find exoplanets, but also to determine the composition of exoplanet atmospheres, surfaces temperatures, and even the presence of clouds or oceans. From these properties and an understanding of the requirements for life as we know it, the potential habitability of a planet can be assessed. Life might be discovered on these habitable exoplanets by identifying gases produced by organisms or detecting living material on the surface. An alternative approach to finding life is the search for extraterrestrial intelligence (SETI), which looks for artificial electromagnetic transmissions or megastructures. This chapter concludes by considering when and how life might be detected in the near future.


Beda Hofmann

The Shape of Life: Morphological Signatures of ancient Microbial Life in Rocks

Characteristic morphologies of higher (eukaryotic) life may be preserved as fossils for millions of years. In contrast, prokaryotic microbial cells lack characteristic morphologies and leave poor fossils. But unique morphologies from complex microbial communities may be preserved in rocks: Stromatolites result from sediment accumulation due to the stickiness of excreted slimy substances. Other life-based textures consist of filamentous microbes preserved by mineral precipitation. Mineralization of flexible filaments leads to gravity-oriented textures resembling stalactites. Fossilized filaments permit the recognition of ancient microbial life in subsurface environments such as cavities in volcanics. Stromatolites and mineralized filaments are targets in the search for life on Mars. They may be identified using camera systems on current or planned Mars missions. Mineralized microbial fabrics are easily visible signatures of life but identification needs confirmation by other methods. The morphology of fossilized microbial textures is caused by basic characteristics of life: The stickiness of excreted substances and the tendency of many microbes to produce flexible filaments.


Antonio Lazcano

Precellular Evolution and the Origin of Life: some Notes on Reductionism, Complexity and Historical Contingency

The secular vision of biological phenomena is a major intellectual watershed that permeates the scientific and philosophical treatises written from the start of the 19th century onwards. Although Darwin consciously avoided discussing the origin of life, he favored the possibility that it could appear by natural processes from simple inorganic compounds, and provided an evolutionary framework that implicitly assumed that assumed that living organisms were the outcome of a gradual transformation of lifeless matter. The heterotrophic origin proposed by Oparin, Haldane and few others in the 1920’s was a scientific outcome of such evolutionary perspective. The debates that followed represent not only contrasting views of the nature of life, but also led to ideological discussions that reached a surprising intensity in the years following the 1953 Miller-Urey experiment, which demonstrated the ease with which organic compounds could be synthesized under primitive reducing conditions. Following the Miller-Urey experiment attempts to understand the origin of life were shaped to a considerable extent by the development of molecular biology and, in socio-political terms, by the atmosphere created by Cold War tensions. Although as late as 1942 the possibility that bacteria were endowed with genetic material was held in doubt, the molecularization of biology led to what can be termed today the RNA World.


Michel Morange

Science and Philosophy faced with the Question of Life in the 21st Century

Scientists in general, and biologists in particular, have always addressed the question of life, implicitly or explicitly. Biological sciences have rapidly developed and transformed in the last decades, and it is important for philosophers to scrutinize these transformations. Philosophers are not prisoners of the discourses of scientists, but they cannot ignore them. In this contribution, I characterize these recent evolutions, and the philosophical issues that they raise. The informational vision of molecular biology has progressively faded with the hypothesis of an RNA world, the development of epigenetics, and the return of a metabolic vision of life. The partial failure of the search for a minimal genome, and the important role attributed to viruses in the transformations of organisms support a more systemic view of life. The increasing place of contingency in evolutionary scenarios, and the demonstration of its importance at the molecular level, are not without consequence for the question of the origin of life: well-designed scenarios left the place to an historical, contingent, process. Building artificial organisms has become a reasonable scientific project. The question of life is considered as solved, and separated from the questions of mind and consciousness that remain so far beyond the power of scientists.


Claus Beisbart

What is Life? And why is the Question still open?

The question of what life is has elicited numerous attempts to define life, none of which has achieved widespread consensus. This chapter assesses the difficulties of defining life and makes a proposal how to proceed. It brings work about definition to bear on the question of what life is. Under a natural interpretation, this question asks for a descriptive definition of “life”, i.e. an account of our concept of life. The chapter discusses objections that Cleland and Chyba have raised against the project of providing a descriptive definition of “life”. It is argued that a descriptive definition may contain significant insights. Nevertheless, the most fruitful method for such a definition, analysis in terms of necessary and jointly sufficient conditions, is unlikely to succeed for life. This by itself is not problematic, since other concepts escape analysis too and since there are alternative ways to obtain a descriptive definition. We nevertheless face a dilemma: Every account of life will either be unprincipled or incompatible with some ways in which we talk about life. I reject a recent attempt by Cleland and Chyba to escape this dilemma and instead propose a Carnapian explication of life for the purposes of biological research.


Christian Weidemann

Is the Origin of Life a Fluke? Why the Chance Hypothesis should not be dismissed too quickly

The origin of life on Earth is one of the great unsolved mysteries of science. Although no complete account of life’s beginnings is available and although no life forms that emerged independently on other planets have been discovered, most origin-of-life-researchers and astrobiologists dismiss a chance scenario out of hand. I argue that this is a mistake for at least two reasons. Firstly, given a sufficiently big and adequately variegated cosmos any finite chance of life emerging on Earth-like planets will virtually guarantee the formation of life somewhere. An observational selection effect could then explain why the cosmic neighbourhood we find ourselves in is a very special place (Vast Cosmos Argument). Secondly, as White (2007) has pointed out, there seems to be no conceivable a priori reason to suppose that processes by which complex molecules arise are more likely to be unintentionally biased towards self-replicating, life-producing molecules than to other types of molecules (Indifferent Nature Argument). Objections to both arguments are discussed and rejected.


Milan M. Ćirković 

Some contemporary – and persistent – Fallacies about Astrobiology

We are witnessing a paradox: the whole “astrobiological revolution” since about 1995 has brought about great expansion of our knowledge, but has not, so far, dispelled some of the most serious older prejudices and fallacies about the search for life in the most general cosmic context. Some of those fallacies date back to the time of Alfred Russel Wallace and have been reinforced by persistent opposition to the broadest acceptance of neodarwinian evolution. Others have emerged as a reaction to both the beginning of the Space Age and the onset of SETI programs in 1960s. Finally, a strand of confusion stems from the controversies surrounding anthropocentrism and its new “lease on life” obtained as a consequence of various antiscientific, postmodern, social constructivist, creationist, and quasihumanist ideologies in the last couple of decades. All these fallacies offer a fine opportunity for highlighting some of the basics of contemporary epistemology and philosophy of science.


Susan Schneider

Superintelligent Artificial Intelligence and the Postbiological Cosmos Approach

Superintelligent artificial intelligence (SAI) is a hypothetical form of AI which is able to exceed the best in human-level intelligence in every field – social skills, general wisdom, scientific creativity, and so on. The last few years have seen the widespread recognition that sophisticated AI is under development on Earth. In the domain of astrobiology, several people have argued that it is likely that the most intelligent aliens will be postbiological. In this piece, I bring these two domains together. First, I’ll identify new directions for the postbiological intelligence approach in astrobiology based on work on superintelligence.  Second, while much discussion of SAI has focused on the control problem, it is also important to consider under what circumstances we can understand the computations of SAI.  For anticipating ways that we can understand SAI may assist our efforts to control it. I identify several developments from cognitive science and philosophy that may yield some understanding into SAI. I also discuss the social implications of these issues.


Andreas Losch

What Theology can contribute to the Question "What is Life?"

While the concept of “life” in general is a rather broad one, in this chapter I want to sketch shortly how science and philosophy close to science have dealt with the big question what life is and I will ask whether the fundamental answers given may suffice. To pursue our task, we need to start with a contribution by Erwin Schrödinger; from the scientific beginnings, there was a focus on the physical and chemical level of life. The main body of the chapter then explores the potential contributions of theology to this question as a scientific one. Can theology contribute at all? The famous Swiss theologian Karl Barth preferred to keep the domains of science and theology separated. Nevertheless, misperceptions set aside, I think there are potential contributions of theology to science in our time. Theologian Michael Welker has dedicated a booklet to the issue and gives five answers which shall be applied on the question under consideration. Also, additional answers have been found.


Alexander Maßmann

Autopoietic Systems and the Theology of Creation: On the Nature of Life

Evolving life is autopoietic. By contrast, mechanistic science ignores teleological aspects of life, as in the structural coupling between a bacterium and its environment. While the range and extent of teleology requires careful consideration, this allows for fresh perspectives in the dialogue between theology, science, and philosophy. The purpose of this chapter is to explore this novel terrain. From this perspective, Kant’s half-way house of a regulative idea of teleology will be revised in both a more Darwinian, or mechanistic, and a more thoroughly teleological way. Judeo-Christian traditions, further, do not typically isolate mind and matter, as certain readings of the first creation account of the Bible would have it. Neither is the Apostle Paul a somatophobic spiritualizer. The close intertwining of meaning and physical organization that is characteristic of organisms also shares a feature with Biblical creation traditions. They have already been described in terms of autopoietic theory, but this should be fleshed out further in terms of their prominent notion of the boundary.


Ted Peters

Where there's Life there's Intelligence

This chapter advances the following hypothesis: where there is life there is intelligence. Intelligence is most adequately defined in terms of seven traits: (1) interiority; (2) intentionality; (3) communication; (4) adaptation; (5) problem-solving; (6) self-reflection; and (7) judgment. Humans along with many mammals exhibit all seven traits. This chapter shows how brainless microbes and simple organisms exhibit the first four traits. Reliance on such a spectrum of traits reveals that all life from the simplest to the most complex can be dubbed intelligent, even though they differ in levels of complexity. An important implication of this argument is this: the astrobiologist searching our solar system should look for various degrees of intelligence, not unintelligent life.


Juan Pablo Marrufo del Torro, SJ

Life in the universe, incarnation and salvation. A conversation between Christianity and the Scientific Possibilities of Extra Terrestrial Life

In this chapter, I address the implications that our search for Extra Terrestrial Intelligent life (ETI) has on the belief of the Incarnation. Our recent scientific understandings of life, intelligence, and the discovery of exoplanets prompts us to think on the possibilities of the existence of intelligent life in the universe. The possibility of its existence has implications in our theology and on our religious beliefs. In Christian theology, the question becomes: “Is Jesus of Nazareth the savior of the cosmos? Or is it possible to conceive of multiple incarnations? If incarnation is about salvation (the ontological argument) then one incarnation is enough; however, if incarnation is about relationships (the revelational argument), then it is possible to conceive of multiple incarnations. The best approach is “deep incarnation” in which the Word, or Logos, by becoming incarnate in Jesus, becomes not only human, but matter and atoms, therefore embodying all the elements of the universe and relating to the whole of creation because the Incarnation, more than salvation, is about a relationship between God and creation.


Taede Smedes

Talking Lions, intelligent Aliens, and knowing God – Some epistemological Reflections on a speculative Issue

This chapter offers some philosophical and theological reflections regarding the issue how and to what extent human expectations influence and bias reflecting on the possibility of extraterrestrial intelligence and extraterrestrial religiosity. It is argued, first of all, that because of our biological heritage (especially the cognitive niche that humans inhabit) and the cognitive constraints that result from this, we cannot rule out the possibility that we are unable to recognize extraterrestrial life even if it exists. This conclusion then is taken one step further and applied to discussions in the areas of philosophy of religion and theology. It is argued that if god concepts supervene on the cognitive functioning of human beings (as the cognitive science of religion claims), and if the cognitive functioning in turn supervenes on biological properties (without being reducible to them), then god concepts may be limited to humans only. If so, the possibility cannot be excluded that intelligent extraterrestrial beings lack religion and god concepts altogether.

Andreas Losch


Antonio Lazcano

A Sceptic's afterword

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