Is Life Unique?

Abel, David

doi:10.3390/life2010106

Cited by 17 publications

(12 citation statements)

References 143 publications

(160 reference statements)

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“…Another vote for an insufficiency of dissipative systems for understanding life's origin is a statement [ 148 , p. 211, 149 ] that dissipative structures ‘occur spontaneously according to natural “law” propensities and are purely physicodynamic’, but that they cannot fully account for life's origin because they ‘involve no steering toward algorithmic success' provided by ‘prescriptive information’. We assert that mainstream science pursues what can be understood via physical and chemical laws, and that any suggested exception belongs to the realm of pseudo-science.…”

Section: Gard Is a Dissipative Systemmentioning

confidence: 99%

Systems protobiology: origin of life in lipid catalytic networks

Lancet

Zidovetzki

Markovitch

2018

J. R. Soc. Interface.

127

183

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Life is that which replicates and evolves, but there is no consensus on how life emerged. We advocate a systems protobiology view, whereby the first replicators were assemblies of spontaneously accreting, heterogeneous and mostly non-canonical amphiphiles. This view is substantiated by rigorous chemical kinetics simulations of the graded autocatalysis replication domain (GARD) model, based on the notion that the replication or reproduction of compositional information predated that of sequence information. GARD reveals the emergence of privileged non-equilibrium assemblies (composomes), which portray catalysis-based homeostatic (concentration-preserving) growth. Such a process, along with occasional assembly fission, embodies cell-like reproduction. GARD pre-RNA evolution is evidenced in the selection of different composomes within a sparse fitness landscape, in response to environmental chemical changes. These observations refute claims that GARD assemblies (or other mutually catalytic networks in the metabolism first scenario) cannot evolve. Composomes represent both a genotype and a selectable phenotype, anteceding present-day biology in which the two are mostly separated. Detailed GARD analyses show attractor-like transitions from random assemblies to self-organized composomes, with negative entropy change, thus establishing composomes as dissipative systems—hallmarks of life. We show a preliminary new version of our model, metabolic GARD (M-GARD), in which lipid covalent modifications are orchestrated by non-enzymatic lipid catalysts, themselves compositionally reproduced. M-GARD fills the gap of the lack of true metabolism in basic GARD, and is rewardingly supported by a published experimental instance of a lipid-based mutually catalytic network. Anticipating near-future far-reaching progress of molecular dynamics, M-GARD is slated to quantitatively depict elaborate protocells, with orchestrated reproduction of both lipid bilayer and lumenal content. Finally, a GARD analysis in a whole-planet context offers the potential for estimating the probability of life's emergence. The invigorated GARD scrutiny presented in this review enhances the validity of autocatalytic sets as a bona fide early evolution scenario and provides essential infrastructure for a paradigm shift towards a systems protobiology view of life's origin.

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Section: Gard Is a Dissipative Systemmentioning

confidence: 99%

Systems protobiology: origin of life in lipid catalytic networks

Lancet

Zidovetzki

Markovitch

2018

J. R. Soc. Interface.

127

183

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“…32-35] as durable physiochemical mechanisms exhibiting a high degree of complexity, and capable of self-regulation and homeostasis via metabolic processes that involve an exchange of energy and matter with their surroundings. Since Henderson's day, many other authors have formulated definitions of life and organisms [6], most of which include the same basic elements alluded to by Henderson…”

Section: Carbonmentioning

confidence: 99%

“…Finally, the majority of all aquatic organisms, derive little if any direct adaptive utility from water's high latent heat of evaporation. 6 The high thermal capacity of water also poses a challenge for exotherms seeking to warm themselves on cold mornings. Small terrestrial organisms like bumble bees and dragonflies must shiver to raise the temperature of their muscles before flying.…”

Section: Watermentioning

confidence: 99%

“…A complex cardiovascular system for the circulation of nutrients, the elimination of waste, and the exchange of gases is an essential aspect of the design of all advanced metabolically active organisms. In contrast, simple, single-celled, carbon-based life forms can obtain the nutrients to supply their metabolic needs 6 The high evaporative cooling of water does play an important role in maintaining the temperature stability of the hydrosphere, which is of benefit indirectly for all life on earth. Henderson discusses the importance of this property of water in The Fitness (3: 92-102).…”

Section: Watermentioning

confidence: 99%

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The Place of Life and Man in Nature: Defending the Anthropocentric Thesis

Denton¹

2013

BIO-Complexity

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Here I review the claim that the order of nature is uniquely suitable for life as it exists on earth (Terran life), and specifically for living beings similar to modern humans. I reassess Henderson's claim from The Fitness of the Environment that the ensemble of core biochemicals that make up Terran life possess a unique synergistic fitness for the assembly of the complex chemical systems characteristic of life. I show that Henderson's analysis is still remarkably consistent with the facts one century after it was written. It is still widely accepted even among researchers in astrobiology. I also review the evidence for believing that many of the properties of the same core set of biochemicals are specifically fit for the physiology of complex terrestrial beings resembling modern humans. I show that none of the recent advances in the field of extremophile biology, alternative biochemistries, or recent allusions to apparent defects in the fitness of nature for Terran life significantly undermine the core argument, that nature is peculiarly fit for carbon-based Terran life, and especially for the physiology of complex terrestrial beings resembling modern humans.

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“…Of all the intricate relationships in biological organization, the emergence of coded protein synthesis is often said to represent the most enigmatic hindrance to comprehending life’s emergence in terms of physical principles, which is exceedingly difficult to overcome. David Abel has even gone so far as to seriously question the feasibility of such a quest on ontological grounds [ 150 , 151 ]. In an overbearing tone he denounces rational attempts to understand part of the problem by refining physicodynamic theories as ‘wishful thinking’ for so long as no counter-example can be produced of “ non trivial, unaided spontaneous optimization of formal function by truly natural process ” to falsify his self-proclaimed “ null hypothesis ” that “ physicodynamics alone cannot organize itself into formally functional systems requiring algorithmic optimization ” [ 150 ].…”

Section: Integrative Perspectivesmentioning

confidence: 99%

Life’s Order, Complexity, Organization, and Its Thermodynamic–Holistic Imperatives

Egel

2012

Life

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In memoriam Jeffrey S. Wicken (1942–2002)—the evolutionarily minded biochemist, who in the 1970/80s strived for a synthesis of biological and physical theories to fathom the tentative origins of life. Several integrative concepts are worth remembering from Wicken’s legacy. (i) Connecting life’s origins and complex organization to a preexisting physical world demands a thermodynamically sound transition. (ii) Energetic ‘charging’ of the prebiosphere must precede the emergence of biological organization. (iii) Environmental energy gradients are exploited progressively, approaching maximum interactive structure and minimum dissipation. (iv) Dynamic self-assembly of prebiotic organic matter is driven by hydrophobic tension between water and amphiphilic building blocks, such as aggregating peptides from non-polar amino acids and base stacking in nucleic acids. (v) The dynamics of autocatalytic self-organization are facilitated by a multiplicity of weak interactions, such as hydrogen bonding, within and between macromolecular assemblies. (vi) The coevolution of (initially uncoded) proteins and nucleic acids in energy-coupled and metabolically active so-called ‘microspheres’ is more realistic as a kinetic transition model of primal biogenesis than ‘hypercycle replication’ theories for nucleic acid replicators on their own. All these considerations blend well with the current understanding that sunlight UV-induced photo-electronic excitation of colloidal metal sulfide particles appears most suitable as a prebiotic driver of organic synthesis reactions, in tight cooperation with organic, phase-separated, catalytic ‘microspheres’. On the ‘continuist vs. miraculist’ schism described by Iris Fry for origins-of-life considerations (Table 1), Wicken was a fervent early protagonist of holistic ‘continuist’ views and agenda.

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Is Life Unique?

Cited by 17 publications

References 143 publications

Systems protobiology: origin of life in lipid catalytic networks

Systems protobiology: origin of life in lipid catalytic networks

The Place of Life and Man in Nature: Defending the Anthropocentric Thesis

Life’s Order, Complexity, Organization, and Its Thermodynamic–Holistic Imperatives

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