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Astrophysical Sources of Energy for Life

 

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Origin of Life research – welcome to a new initiative

Whence do we come? Throughout the history of human thinking, these four words expressed a deep and nagging metaphysical conundrum. The idea of evolution lets us pose the same question from a material viewpoint and, followed back in time, it ultimately takes the form of How did life originate? Coming to grips with the problem within the realm of accepted standards of science is an almost overwhelmingly complex undertaking, frought with many uncertainties. Any such enterprise necessarily starts from one (and only one) fundamental postulate: Life did originate, which means to say our universe had a defined starting point and early in its history it exclusively contained inanimate matter which, at some later stage, by a process still unknown, gave rise to living organisms. Approaching a valid description of that process is the objective of scientific research into the origins of life.

Chances are slim, the true sequence of events will ever be reconstructed with precision. This leaves to Origin of Life research the task of determining a corridor of possibilities within which the historic trajectory can reasonably be assumed to fall and of narrowing down this corridor by stepwise elimination of implausible or outright impossible options. Occasionally, the corridor has to be expanded in other places as new insight opens up scenarios not considered before – salient examples being the discoveries of hydrothermal vents along mid-ocean ridges in the 1970s and of catalytic RNA in the 1980s and also the presently growing awareness and appreciation of the deep biosphere.

The foundations upon which to build a heuristic edifice of this kind must be laid by an inventory of constraining physical conditions that prevailed at any relevant point in space and time. For the period from the formation of our solar system to the earliest undisputed existence of life on Earth, material evidence on which to base a clear picture is sparse. This leaves us with constraints of a somewhat diffuse nature and sharpening these is, obviously, a continuing task of utmost importance. Encouragingly, progress in Earth and space sciences indicates that we have not nearly reached maximal resolution yet.

For the time being, all we can do is to lend preliminary credibility to the conceptual framework defined by the constraints as we presently understand them and to fill it with creative conjecture – followed, at each step, by sober, merciless criticism. Experimental falsification is the gold standard in Origin of Life research as it is elsewhere in science – the difference being that any hypothesis of how life arose is bound to have far too many variables and ramifications to be tested in toto in one single experiment. Rather, one has to investigate, one at a time, individual elements that are supposed to have contributed to the grand overall process at a certain point in a certain way.

One line of reasoning proceeds forward in time: Early Earth scenarios are elaborated into models of primordial geochemistry culminating in organic compounds apt as bona fide precursors of contemporary metabolism and macromolecular biosynthesis. Wholesale import of organic material by impactors may have supplemented early Earth chemistry to a decisive degree (it never completely faded until present days). The history of these compounds is not different in principle but is so with respect to assumed time, location and modes of their synthesis. Taken to the extreme, this train of thought leads to the controversial notion of panspermia, which implies an already hospitable but still sterile planet having been seeded with live organisms from interstellar space.

A second line does the reverse: Characteristics shared by all present organisms (like, e.g., the Genetic Code) are used to infer properties and attributes of a lost, hypothetical, last common ancestor. A handshake between the two approaches is not in sight; the geohistoric 'record in the rocks', however, is an ideal complement which provides not only solid landmarks on the time scale but also a wealth of information on past physical and chemical conditions, both experienced and shaped by early life on the planet.

Even though geology and palaeontology deal with hard evidence in the literal sense of the word, there still remains the sometimes slippery problem of interpretation: Is the suggestive morphology of a particular 'microfossil' or an equally suggestive isotope ratio found in a sample of carbonaceous matter a reliable indicator of life or an 'artifact' of inanimate processes? Once such a material trace is generally accepted as trustworthy: How close is it to the true origin of life?

The working group Origin of Life of Göttingen Academy of Sciences and Humanities was founded in 2011 in cooperation with the Courant Research Centre Geobiology - with the aim to foster a multidisciplinary discourse on the subject and to instigate and carry out new practical work. With the website you are presently visiting we give an account of our activities and make publicly available abstracts and literature lists of talks given by group members and invited speakers. (For viewing and downloads click on seminar titles listed under "Events"). In the long run, we wish to develop this website into an open resource for use by the entire Origin of Life research community. With this in mind, additional functions are presently being developed and will be installed in due time. The "News" column will occasionally be updated by fresh reports on current developments in Göttingen and elsewhere. Please visit us again soon.

Göttingen, March 28, 2012
Hans-Joachim Fritz
Joachim Reitner

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