Department of Polymer Science, 170 University Avenue, University of Akron, Akron, OH 44325-3909, USA. Bactericidal and detoxification effects of TiO, Linear correlation between inactivation of. Methods to advance this programme include identifying the causal architecture of known biochemical networks by applying candidate measures (such as φ, or other measures of causal architecture [80,81]), and focusing on regulatory networks (information control networks) in ancient biochemical pathways to identify the minimal network architectures necessary to support the causal and informational narrative observed in extant life. Click here to explore this opportunity. (1977) in Encyclopaedia of Ignorance (Duncan, R. and Weston-Smith, M., eds), pp.
This was the problem von Neumann wished to solve. It is the functionality of the expressed RNAs and proteins—not the bits—that is biologically important.
Before enzymes and templates: theory of surface metabolism. However, the genome is only a small part of the story. Top-down causation has an extensive literature so will not be reviewed here [23,24,68–70,73–75]. are long-chain isoprenoid lipids found in plants. It makes sense to try to explain life's origin only if it resulted from processes of moderately high probability, so that we can reasonably expect to give an account in terms of known science.
Chemical synthesis of lipids and the origin of life. (1985) Photochemical reactions in interstellar grains-photolysis of CO, NH 3 and H 2 O. Biochemical Evolution II: Origin of Life in Tubular Microstructures on Weathered Feldspar Surfaces . Protocells, the first life-like entities, likely contained three molecular components: Mineral surface directed membrane assembly. In analogue chemical systems, information is contained in a continuously variable composition of an assembly of molecules rather than in a discrete string of digital bits. Get a printable copy (PDF file) of the complete article (161K), or click on a page image below to browse page by page. Vesicle encapsulation of a nonbiological photochemical system capable of reducing NAD.
Cast in the language of the previous section, trivial replicators process information strictly in the passive sense. For example, much of the information digitally stored in DNA must first be transcribed and translated before it becomes algorithmically meaningful in the context of the cell where it is then processed as analogue information through protein interaction networks. For example, a trivial replicator, such as a crystal, is one that may be specified by an algorithm containing far fewer bits than the system it describes. Although it has been notoriously difficult to pin down precisely what is it that makes life so distinctive and remarkable, there is general agreement that its informational aspect is one key property, perhaps the key property. 4 https: ... of the origin of life on other solid worlds beyond Earth. Identifying the parallels between biological systems, such as the human nervous system, and computers, and drawing inspiration from Turing's work on universal computation, von Neumann  sought a formalism that would include both natural and artificial systems. Reactive oxygen species at the oxide/water interface: formation mechanisms and implications for prebiotic chemistry and the origin of life. RNA world was the first biological world or whether some simpler world preceded it. It therefore provides a measure of the distributed information generated by the network as a whole as a result of its causal architecture. At least superficially, this appears to be very similar to the case presented by biological systems where the update rules change in response to information read-out from the current state (as we discuss below, both are an example of top-down causation via information control). Cadmium sulfide-particle-mediated transmembrane photoelectron transfer in surfactant vesicles. Is silica really an anomalous oxide? The modern experimental study of the origin of the first life on earth is now entering its fourth decade, if we date the inception of this field of research to Stanley Miller's pioneering work in the early 1950s. In so doing, it forces new thinking in how life might have arisen on a lifeless planet, by shifting emphasis to the origins of information control, rather than, for example, the onset of Darwinian evolution or the appearance of autocatalytic sets (i.e. Enter your email address below and we will send you the reset instructions.
In that respect, we regard the case of the RNA world as currently understood as falling short of being truly living. Synthesis of long prebiotic oligomers on mineral surfaces. Self-assembly of phosphate amphiphiles in mixtures of prebiotically plausible surfactants. The influence of mineral matrices on the thermal behavior of glycine. Micelles are usually formed by single-chain amphiphiles, since it is difficult to fit two chains into a micellar structure. Steep pH gradients and directed colloid transport in a microfluidic alkaline hydrothermal pore. Schrödinger recognized this key distinction in his take on What is life? and particle size of the mineral. A major unsolved problem is to determine how information control emerges ab initio, for example, in an RNA world setting, from chemical kinetics, as well as how primitive control mechanisms might evolve and become increasingly refined after ‘algorithmic takeover’ has occurred. This system would then have undergone further hardware upgrades or ‘genetic-takeovers’ to arrive at the DNA–protein world we observe today . S.I.W. For this rather deep reason, it may be that life had to be ‘bimolecular’ from the start. Walker et al. We point out a curious philosophical implication of the algorithmic perspective: if the origin of life is identified with the transition from trivial to non-trivial information processing—e.g. The origin of life may thus be identified when information gains top-down causal efficacy over the matter that instantiates it. This may explain Darwin's own reluctance to speculate on the subject, ‘One might as well speculate about the origin of matter’, he quipped. Unfortunately, the way that information operates in biology is not easily characterized [10,14].
Staging life in an early warm ‘seltzer’ocean. This is not without good reason: the origin of translation—mediating what is known of the transition from trivial to non-trivial8—is notoriously difficult to pin down, amounting to an algorithmic takeover of information stored in one molecular species (nucleic acids) that becomes operable over another structurally and chemically very different species (peptides). A global scale scenario for prebiotic chemistry: silica-based self-assembled mineral structures and formamide. On the origin of biochemistry at an alkaline hydrothermal vent.
As remarked above, the proteome, and in fact nearly all biochemical interactions in the cell, processes information in an analogue format, i.e. In spite of the striking similarities between an UC and modern life, there are some important differences. RNA is unique in that it can fill both roles, acting as both a genetic polymer and a biochemical catalyst, with novel expanded roles for functional RNAs continually being discovered. The instructional, or algorithmic, nature of biological information was long ago identified as a key property, and an early attempt to formalize it was made by von Neumann. The manner in which information flows through and between cells and sub-cellular structures is quite unlike anything else observed in nature. All rights reserved. It is probable that non-trivial information processing systems with delocalized information are more evolutionarily robust given that information can be preserved in the face of changing environmental conditions due the physical separation of information and its material representation. Such a definition also addresses the vexed issue of what constitutes ‘almost life’. The utility of this approach is that it provides a clear definition of what one should look for: a transition from bottom-up to top-down causation and information flow. In this framework, the origin of life would mark the first appearance of this reversal in causal structure, and as such is a unique transition in the physical realm (marking the transition from trivial to non-trivial information processing as discussed earlier). Argarwal VK, Schutte W, Greenberg JM etal. In terms of computer language, in living systems chemistry corresponds to hardware and information (e.g. Mineral surfaces, geochemical complexities, and the origins of life. Fermentation –archaea Sugar ethyl alcohol + 2 units of energy 2. We make no attempt to engage this notorious philosophical topic here, because it is irrelevant for the present discussion whether information is in fact a fundamental causal agent (which would represent a radical departure from standard physics), or may be treated merely phenomenologically as an effective causal agent. thermodynamic phase transitions), with the crucial distinction that determining which phase (non-life or life) a given system is in requires dynamical information and therefore can only be inferred by identifying causal architecture. 5 The mapping between extant life and a von Neumann automaton is rather loose. The chemist George Whitesides, for example, has stated, ‘How remarkable is life? Amphiphilic components of the Murchison carbonaceous chondrite: surface properties and membrane formation.
either analogue or digital systems that lack information control), which, although certainly important to the story of life's emergence, do not rigorously define how/when life emerges as a function of chemical complexity.
Surface acidity and aqueous hydrolysis revisited. Energy transduction inside of amphiphilic vesicles: encapsulation of photochemically active semiconducting particles. It then follows from simple statistics that there will have been a large ensemble of systems proceeding down the pathway toward life, and no obvious reason why only one member successfully completed the journey. Download preview PDF.
It also permits a broader view of life, where the same underlying principles would permit understanding of living systems instantiated in different chemical substrates (including potentially non-organic substrates). a class of lipids that are an integral component of all cell membranes. As we discuss below, because of the organizational structure of systems capable of processing algorithmic (instructional) information, it is not at all clear that a monomolecular system, where a single polymer plays the role of catalyst and informational carrier, is even logically consistent with the organization of information flow in living systems, because there is no possibility of separating information storage from information processing (that being such a distinctive feature of modern life). An important feature of UCs is that they operate on universality classes.4 In principle, an UC is capable of constructing any object within a given universality class (including itself, if it is a member of the relevant class). Resolving the enigma of prebiotic C-O-P bond formation: prebiotic hydrothermal synthesis of important biological phosphate esters. The power of the Darwinian paradigm is precisely its capacity to unify such diverse phenomena, particularly across the tree of life—all that is required are the well-defined processes of replication with variation and selection. What are the biochemical simi- larities and differences among the many forms of life?