Current origin of life proposals
http://reasonandscience.heavenforum.org/t2468-current-origin-of-life-proposals
Regularly science journals and papers come up with new OOL ( origin of life ) scenarios.
1. The Emergence of Life as a First-Order Phase Transition
2. Molecules assemble in water, hint at origins of life
3. Meteorite Chemicals May Have Started Life on Earth—and Space
4. Thermodynamic origin of life
5. Life on Earth may have begun as dividing droplets
6. Hydrothermal vent models transform the origins of life from unlikely to near-inevitable.
7. The origins of life -- the 'protein interaction world' hypothesis
8. Primordial soup hypothesis
9. Electric Spark hypothesis
10. The minimotif synthesis hypothesis for the origin of life
11. The Oparin-Haldane Hypothesis
12. Origin of Life: The Heterotroph Hypothesis
13. Bubbles May Have Speeded Life's Origins on Earth
14. The Origin Of Life Dual Origin Hypothesis
15. Thermodynamic dissipation theory for the origin of life
16. Protein World Hypothesis on the Origin of Life
17. The Zinc world hypothesis
18. Origin of Life - The Sweet Crystal Hypothesis
19. Pyrite formation, the first energy source for life: a hypothesis
20. Hypothesis: the origin of life in a hydrogel environment
21. Submarine hot springs and the origin of life
22. Organic Aerosols and the Origin of Life: An Hypothesis
23. Thermoreduction, a hypothesis for the origin of prokaryotes
24. The [GADV]‐protein world hypothesis
25. The RNA first hypothesis
26. The metabolism first hypothesis
http://www.molevol.de/gallery/Origin-of-life_high.mp4
Serpintinisation
Serpentinization is a process whereby rock (usually ultramafic) is changed, with the addition of water into the crystal structure of the minerals found in the rock.
Transition metal sulfides
From the biological side, many phylogenomic studies conclude that clades exclusive to hydrothermal vents are the deepest branches in the tree of life. Further, most metabolic enzymes that catalyze anaerobic reactions with small gas molecules depend on transition metal sulfide clusters that have been noted to resemble minerals common to vents
The emergence of life from iron monosulphide bubbles at a submarine hydrothermal redox and pH front
Life on Earth may have begun as dividing droplets
In a primordial soup on ancient Earth, droplets of chemicals may have paved the way for the first cells. Shape-shifting droplets split, grow and split again in new computer simulations. The result indicates that simple chemical blobs can exhibit replication, one of the most basic properties of life, physicist Rabea Seyboldt of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, reported March 16 at a meeting of the American Physical Society.
https://www.sciencenews.org/article/life-earth-may-have-begun-dividing-droplets
Universal ancestor of all life on Earth was only half alive
One characteristic of almost all living cells is that they pump ions across a membrane to generate an electrochemical gradient, then use that gradient to make the energy-rich molecule ATP. Martin’s results suggest LUCA could not generate such a gradient but could harness an existing one to make ATP.
That fits in beautifully with the idea that the first life got its energy from the natural gradient between vent water and seawater, and so was bound to these vents. Only later did the ability to generate gradients evolve, allowing life to break away from the vents on at least two occasions – one giving rise to the first archaea, the other to bacteria.
https://www.newscientist.com/article/2098564-universal-ancestor-of-all-life-on-earth-was-only-half-alive/
The Emergence of Life as a First-Order Phase Transition
March 1, 2017
Here we present a model for the emergence of life in which replicators are explicitly coupled to their environment through the recycling of a finite supply of resources. The model exhibits a dynamic, first-order phase transition from nonlife to life, where the life phase is distinguished by selection on replicators. We show that environmental coupling plays an important role in the dynamics of the transition. The transition corresponds to a redistribution of matter in replicators and their environment, driven by selection on replicators, exhibiting an explosive growth in diversity as replicators are selected.
http://online.liebertpub.com/doi/abs/10.1089/ast.2016.1481?journalCode=ast&#utm_source=ETOC&utm_medium=email&utm_campaign=ast
Molecules assemble in water, hint at origins of life
February 20, 2013
Researchers are exploring an alternate theory for the origin of RNA: they think the RNA bases may have evolved from a pair of molecules distinct from the bases we have today. This theory looks increasingly attractive, as researchers were able to achieve efficient, highly ordered self-assembly in water with small molecules that are similar to the bases of RNA.
https://www.sciencedaily.com/releases/2013/02/130220123332.htm
Meteorite Chemicals May Have Started Life on Earth—and Space
April 16, 2015
https://www.scientificamerican.com/article/meteorite-chemicals-may-have-started-life-on-earth-and-space/
The molecules that kick-started life on primordial Earth could have been made in space and delivered by meteorites, according to researchers in Italy. The group synthesised sugars, amino acids and nucleobases with nothing more than formamide, meteorite material and the power of a simulated solar wind, replicating a process they believe cooked up a prebiotic soup long before life existed on Earth.
NASA Has Found The Ingredients For Life On Saturn’s Moon Enceladus
(Reuters) – Ice plumes shooting into space from Saturn’s ocean-bearing moon Enceladus contain hydrogen from hydrothermal vents, an environment that some scientists believe led to the rise of life on Earth, research published on Thursday showed.The discovery makes Enceladus the only place beyond Earth where scientists have found direct evidence of a possible energy source for life, according to the findings in the journal Science.Similar conditions, in which hot rocks meet ocean water, may have been the cradle for the appearance of microbial life on Earth more than 4 billion years ago.
https://www.galaxymonitor.com/nasa-has-found-the-ingredients-for-life-on-saturns-moon-enceladus/
Thermodynamic origin of life
9 September 2010
Understanding the thermodynamic function of life may shed light on its origin. Life, as are all irreversible processes, is contingent on entropy production. Entropy production is a measure of the rate of the tendency of Nature to explore available microstates. The most important irreversible process generating entropy in the biosphere, and thus facilitating this exploration, is the absorption and transformation of sunlight into heat. Here we hypothesize that life began, and persists today, as a catalyst for the absorption and dissipation of sunlight at the surface of shallow seas. The resulting heat is then efficiently harvested by other irreversible processes such as the water cycle, hurricanes, and ocean and wind currents. RNA and DNA are the most efficient of all known molecules for absorbing the intense ultraviolet light that could have penetrated the dense early atmosphere, and are remarkably rapid in transforming this light into heat in the presence of liquid water. From this perspective, the origin and evolution of life, inseparable from water and the water cycle, can be understood as resulting from the natural thermodynamic imperative of increasing the entropy production of the Earth in its interaction with its solar environment. A mechanism is proposed for the reproduction of RNA and DNA without the need for enzymes, promoted instead through UV light dissipation and the ambient conditions of prebiotic Earth.
https://arxiv.org/pdf/0907.0042.pdf
The Emergence of Cells During the Origin of Life
Science 08 Dec 2006:
simple physicochemical properties of elementary protocells can give rise to essential cellular behaviors, including primitive forms of Darwinian competition and energy storage. Such preexisting, cooperative interactions between the membrane and encapsulated contents could greatly simplify the transition from replicating molecules to true cells. They also suggest intriguing possibilities for further investigation. For example, a corollary of vesicle competition is that a charged genetic polymer, such as nucleic acid, would be much more effective at driving membrane uptake than an electrically neutral polymer, because most of the osmotic pressure is due to counterions associated with the charged polymer. Could this influence the natural selection of the genetic material itself? Furthermore, competition for membrane molecules would favor stabilized membranes, suggesting a selective advantage for the evolution of cross-linked fatty acids (e.g., di- and triglycerides) and even the phospholipids of today. Greater membrane stability leads to decreased dynamics, however, and the evolutionary solutions to this problem (e.g., permeases, synthetic enzymes) could cause a “snowball” effect on the complexity of early life (16). Exploration of these minimal systems promises to lead to more exciting insights into the origins of biological complexity.
http://science.sciencemag.org/content/314/5805/1558.full?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=irene%20chen&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT
Chemists may be zeroing in on chemical reactions that sparked the first life
By Robert F. ServiceMay. 19, 2017 , 6:00 AM
DNA is better known, but many researchers today believe that life on Earth got started with its cousin RNA, because that nucleic acid can act as both a repository of genetic information and a catalyst to speed up biochemical reactions. But those favoring this “RNA world” hypothesis have struggled for decades to explain how the molecule’s four building blocks could have arisen from the simpler compounds present during our planet’s early days. Now, chemists have identified simple reactions that, using the raw materials on early Earth, can synthesize close cousins of all four building blocks. The resemblance isn’t perfect, but it suggests scientists may be closing in on a plausible scenario for how life on Earth began.
RNA’s four building blocks are called nucleotides. Each is composed of ribose, a ring-shaped sugar molecule, connected to one of four different ring-shaped “bases,” adenine (A), guanine (G), cytosine (C), and uracil (U). C and U are structurally similar to each other and collectively known as pyrimidines, whereas A and G resemble each other and are known as purines. In 2009, researchers led by Matthew Powner and John Sutherland at the Medical Research Council in Cambridge, U.K., came up with the first plausible chemical reactions that could have synthesized pyrimidines on early Earth. But very different reactions, in different conditions, seemed necessary to make purines. That begged the question of how all four nucleotides could have wound up in the same place to give rise to the first “living” RNA molecules.
http://www.sciencemag.org/news/2017/05/chemists-may-be-zeroing-chemical-reactions-sparked-first-life?utm_source=newsfromscience&utm_medium=facebook-text&utm_campaign=firstlife-13132
Life on Earth may have begun as dividing droplets
In a primordial soup on ancient Earth, droplets of chemicals may have paved the way for the first cells. Shape-shifting droplets split, grow and split again in new computer simulations. The result indicates that simple chemical blobs can exhibit replication, one of the most basic properties of life, physicist Rabea Seyboldt of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, reported March 16 at a meeting of the American Physical Society.
Within a liquid, small droplets of particular chemicals can separate out, like beads of oil in water. Such globules typically remain spherical, growing as they merge with other drops. But in simulations, Seyboldt and colleagues found that droplets might behave in a counterintuitive way under certain conditions, elongating and eventually dividing into two.
https://www.sciencenews.org/article/life-earth-may-have-begun-dividing-droplets?tgt=nr
Hydrothermal vent models transform the origins of life from unlikely to near-inevitable.
Evolution only seems to move toward greater order; in the larger scheme, it’s downhill all the way. Vent models posit that given the initial conditions, the emergence of life was not a near-miracle. It was inevitable.
http://nautil.us/issue/37/currents/the-fly-in-the-primordial-soup
The origins of life -- the 'protein interaction world' hypothesis: protein interactions were the first form of self-reproducing life and nucleic acids evolved later as memory molecules.
The 'protein interaction world' (PIW) hypothesis of the origins of life assumes that life emerged as a self-reproducing and expanding system of protein interactions. In mainstream molecular biology, 'replication' refers to the material copying of molecules such as nucleic acids. However, PIW is conceptualized as an abstract communication system constituted by the interactions between proteins, in which 'replication' happens at the level of self-reproduction of these interactions between proteins.
https://www.ncbi.nlm.nih.gov/pubmed/15694682
Primordial soup hypothesis
Life on Earth began more than 3 billion years ago, evolving from the most basic of microbes into a dazzling array of complexity over time. But how did the first organisms on the only known home to life in the universe develop from the primordial soup? One theory involved a "shocking" start. Another idea is utterly chilling. And one theory is out of this world! Inside you'll learn just how mysterious this all is, as we reveal the different scientific theories on the origins of life on Earth.
https://www.livescience.com/13363-7-theories-origin-life.html
Electric Spark hypothesis
Lightning may have provided the spark needed for life to begin.
Electric sparks can generate amino acids and sugars from an atmosphere loaded with water, methane, ammonia and hydrogen, as was shown in the famous Miller-Urey experiment reported in 1953, suggesting that lightning might have helped create the key building blocks of life on Earth in its early days. Over millions of years, larger and more complex molecules could form. Although research since then has revealed the early atmosphere of Earth was actually hydrogen-poor, scientists have suggested that volcanic clouds in the early atmosphere might have held methane, ammonia and hydrogen and been filled with lightning as well.
Or could simple clay have fueled life’s beginning? Read on to find out.
Electric Spark Lightning may have provided the spark needed for life to begin. Electric sparks can generate amino acids and sugars from an atmosphere loaded with water, methane, ammonia and hydrogen, as was shown in the famous Miller-Urey experiment reported in 1953, suggesting that lightning might have helped create the key building blocks of life on Earth in its early days. Over millions of years, larger and more complex molecules could form. Although research since then has revealed the early atmosphere of Earth was actually hydrogen-poor, scientists have suggested that volcanic clouds in the early atmosphere might have held methane, ammonia and hydrogen and been filled with lightning as well. Or could simple clay have fueled life’s beginning? Read on to find out.
https://www.livescience.com/13363-7-theories-origin-life.html
The minimotif synthesis hypothesis for the origin of life
Several theories for the origin of life have gained widespread acceptance, led by primordial soup, chemical evolution, metabolism first, and the RNA world. However, while new and existing theories often address a key step, there is less focus on a comprehensive abiogenic continuum leading to the last universal common ancestor. Herein, I present the “minimotif synthesis” hypothesis unifying select origin of life theories with new and revised steps. The hypothesis is based on first principles, on the concept of selection over long time scales, and on a stepwise progression toward complexity. The major steps are the thermodynamically-driven origination of extant molecular specificity emerging from primordial soup leading to the rise of peptide catalysts, and a cyclic feed-forward catalytic diversification of compounds and peptides in the primordial soup. This is followed by degenerate, semi-partially conservative peptide replication to pass on catalytic knowledge to progeny protocells. At some point during this progression, the emergence of RNA and selection could drive the separation of catalytic and genetic functions, allowing peptides and proteins to permeate the catalytic space, and RNA to encode higher fidelity information transfer. Translation may have emerged from RNA template driven organization and successive ligation of activated amino acids as a predecessor to translation.
https://oatext.com/The-minimotif-synthesis-hypothesis-for-the-origin-of-life.php
The Oparin-Haldane Hypothesis
In the early decades of the 20th century, Aleksandr Oparin (in 1924), and John Haldane (in 1929, before Oparin's first book was translated into English), independently suggested that if the primitive atmosphere was reducing (as opposed to oxygen-rich), and if there was an appropriate supply of energy, such as lightning or ultraviolet light, then a wide range of organic compounds might be synthesised.
Oparin suggested that the organic compounds could have undergone a series of reactions leading to more and more complex molecules. He proposed that the molecules formed colloid aggregates, or 'coacervates', in an aqueous environment. The coacervates were able to absorb and assimilate organic compounds from the environment in a way reminiscent of metabolism. They would have taken part in evolutionary processes, eventually leading to the first lifeforms.
Haldane's ideas about the origin of life were very similar to Oparin's. Haldane proposed that the primordial sea served as a vast chemical laboratory powered by solar energy. The atmosphere was oxygen free, and the combination of carbon dioxide, ammonia and ultraviolet radiation gave rise to a host of organic compounds. The sea became a 'hot dilute soup' containing large populations of organic monomers and polymers. Haldane envisaged that groups of monomers and polymers aquired lipid membranes, and that further developments eventually led to the first living cells.
Haldane coined the term 'prebiotic soup', and this became a powerful symbol of the Oparin-Haldane view of the origin of life.
http://www.simsoup.info/Origin_Landmarks_Oparin_Haldane.html
Origin of Life: The Heterotroph Hypothesis
The anaerobic metabolic processes of the heterotrophs released carbon dioxide into the atmosphere, which allowed for the evolution of photosynthetic autotrophs, which could use light and CO2 to produce their own food. The autotrophs released oxygen into the atmosphere. For most of the original anaerobic heterotrophs, oxygen proved poisonous. The few heterotrophs that survived the change in environment generally evolved the capacity to carry out aerobic respiration. Over the subsequent billions of years, the aerobic autotrophs and heterotrophs became the dominant life-forms on the planet and evolved into all of the diversity of life now visible on Earth.
http://www.sparknotes.com/testprep/books/sat2/biology/chapter8section1.rhtml
Bubbles May Have Speeded Life's Origins on Earth
The role of bubbles in the creation of life on earth is one of the newest approaches to solving the scientific mystery that is probably second in importance only to the problem of how the universe itself began.
No one is suggesting that bubbles might explain everything. But in a new hypothesis receiving close attention, the multitudes of bubbles forming on the surface of the primordial seas must have collected chemicals and concentrated them for synthesis into complex molecules. Eventually, through multistage reactions constantly repeated by uncounted generations of bubbles, the molecules grew in size and ambition, ready for the transition to living, reproducing cells.
http://www.nytimes.com/1993/07/06/science/bubbles-may-have-speeded-life-s-origins-on-earth.html?pagewanted=all
The Origin Of Life Dual Origin Hypothesis
According to the dual origin hypothesis, the cerebral cortex of higher mammals evolved from two primordial brain structures, the amygdala and hippocampal formation. This developmental process defines the orderly principles of cortical connectivity and gives rise to functionally distinct ventral and dorsal systems within the cerebrum. This paper reviews the basic features of the dual origin theory. This model is then applied to understanding symptom production in a number of psychiatric illnesses, with particular reference to recent structural and functional imaging studies. In this paper I propose that psychiatric symptoms can be conceptualized as arising from abnormal processing within dorsal (time-space-motility) or ventral (meaning-motivation) systems, or from a disturbance in the functional interaction/balance between them. Within this framework, one can identify symptom-specific correlations that cross-traditional diagnostic boundaries, as well as potential mechanisms that may explain biologically valid diagnostic entities. Integrating evolutionary, connectional and functional bases across multiple species, the dual origin hypothesis offers a powerful neural systems model to help organize our understanding of psychiatric illness, therein suggesting novel approaches to diagnosis, prevention and treatment.
https://www.ncbi.nlm.nih.gov/pubmed/16356547
Thermodynamic dissipation theory for the origin of life
Understanding the thermodynamic function of life may shed light on its origin. Life, as are all irreversible processes, is contingent on entropy production. Entropy production is a measure of the rate of the tendency of Nature
to explore available microstates. The most important irreversible process generating entropy in the biosphere and, thus, facilitating this exploration, is the absorption and transformation of sunlight into heat. Here we hypothesize that life began, and persists today, as a catalyst for the absorption and dissipation of sunlight on the surface of Archean seas. The resulting heat could then be efficiently harvested by other irreversible processes such as the water cycle, hurricanes, and ocean and wind currents. RNA and DNA are the most efficient of all known molecules for absorbing the intense ultraviolet light that penetrated the dense early atmosphere and are remarkably rapid in transforming this light into heat in the presence of liquid water. From this perspective, the origin and evolution of life, inseparable from water and the water cycle, can be understood as resulting from the natural thermodynamic imperative of increasing the entropy production of the Earth in its interaction with its solar environment. A mechanism is proposed for the reproduction of RNA and DNA without the need for enzymes, promoted instead through UV light dissipation and diurnal temperature cycling of the Archean sea-surface.
http://www.earth-syst-dynam.net/2/37/2011/esd-2-37-2011.pdf
Protein World Hypothesis on the Origin of Life
RNA world hypothesis is widely accepted still now, as an idea by which the origin of life might be explained. But, there are many weak points in the hypothesis. In contrast, I have proposed a more reasonable [GADV]-protein world hypothesis or GADV hypothesis, suggesting that life originated from the protein world, which was formed by pseudo-replication of [GADV]-proteins. In this communication, I will discuss about the origin of life from the point of view of the GADV hypothesis.
https://link.springer.com/article/10.1007/s11084-014-9383-4
The Zinc world hypothesis
The suggested "Zn world" scenario identifies the geological conditions under which photosynthesizing ZnS edifices of hydrothermal origin could emerge and persist on primordial Earth, includes a mechanism of the transient storage and utilization of solar light for the production of diverse organic compounds, and identifies the driving forces and selective factors that could have promoted the transition from the first simple, photostable polymers to more complex living organisms.
https://biologydirect.biomedcentral.com/articles/10.1186/1745-6150-4-26
Origin of Life - The Sweet Crystal Hypothesis
When Cairns-Smith formulated his theory of crystalline ancestry - which accounts for the main mechanism by which life can form from inorganic precursors - he was percieved as not having provided a very detailed scenario for the introduction of organic material. Rather he showed how life can form, demonstrated that genetic takeovers were possible, illustrated that there would be selection pressure for carbon-based systems once they arose, and then suggested that the rest of the story was simply a matter for natural selection.
This state of affairs apparently left some of those who had not read Genetic Takeover unsatisfied. They felt as though the origin of their sort of life had not really been explained at all. They did not see where nucleic acid came from - and the origin of cell walls was still a mystery.
While some of the details have no-doubt been lost to history, it seems that some of the subsequent paths in the early evolution of organisms can be identified with a reasonable level of confidence. Even where this is not the case, it may prove helpful to identify in some detail at least one plausible scenario by which evolution can lead away from crystalline organisms, towards ones more easily recognisable as our ancestors.
http://originoflife.net/sweet_crystal/
Pyrite formation, the first energy source for life: a hypothesis
I here propose a new energy source for an autotrophic origin of life. It is the exergonic formation of pyrite from hydrogen sulfide and ferrous ions
http://www.sciencedirect.com.sci-hub.cc/science/article/pii/S0723202088800018
Hypothesis: the origin of life in a hydrogel environment
A hypothesis is proposed that the first cell(s) on the Earth assembled in a hydrogel environment. Gel environments are capable of retaining water, oily hydrocarbons, solutes, and gas bubbles, and are capable of carrying out many functions, even in the absence of a membrane. Thus, the gel-like environment may have conferred distinct advantages for the assembly of the first cell(s).
http://www.sciencedirect.com.sci-hub.cc/science/article/pii/S0079610704000999
Submarine hot springs and the origin of life
The discovery of hydrothermal vents at oceanic ridge crests and the appreciation of their importance in the element balance of the oceans is one of the main recent advances in marine geochemistry1. It is likely that vents were present in the oceans of the primitive Earth because the process of hydrothermal circulation probably began early in the Earth's history2.
http://www.nature.com.ololo.sci-hub.cc/nature/journal/v334/n6183/abs/334609a0.html
Organic Aerosols and the Origin of Life: An Hypothesis
Recent experimental work has verified the prediction that marine aerosols could have an exterior film of amphiphiles; palmitic, stearic and oleic acids were predominant. Thermodynamic analysis has revealed that such aerosols are energetically capable of asymmetric division. In a prebiotic terrestrial environment, one of the products of such aerosol fission would have been bacterially sized (microns), the other would have been virally sized (tens of nanometers). Plausible avenues for chemical differentiation between the two particles are discussed, and the probabilities for the transition from geochemistry to biochemistry updated in light of recent palaeo fossil studies.
http://link.springer.com.ololo.sci-hub.cc/article/10.1023%2FB%3AORIG.0000009828.40846.b3?LI=true
Thermoreduction, a hypothesis for the origin of prokaryotes
https://www.researchgate.net/profile/Patrick_Forterre2/publication/15551510_Thermoreduction_a_hypothesis_for_the_origin_of_prokaryotes/links/0f317536bc0eb3e30e000000.pdf
The [GADV]‐protein world hypothesis
Based on the fact that RNA has not only a genetic function but also a catalytic function, the RNA world theory on the origin of life was first proposed about 20 years ago. The theory assumes that RNA was amplified by self-replication to increase RNA diversity on the primitive earth. Since then, the theory has been widely accepted as the most likely explanation for the emergence of life. In contrast, we reached another hypothesis, the [GADV]-protein world hypothesis, which is based on pseudo-replication of [GADV]-proteins. We reached this hypothesis during studies on the origins of genes and the genetic code, where [G], [A], [D], and [V] refer to Gly, Ala, Asp, and Val, respectively. In this review, possible steps to the emergence of life are discussed from the standpoint of the [GADV]-protein world hypothesis, comparing it in parallel with the RNA world theory. It is also shown that [GADV]-peptides, which were produced by repeated dry-heating cycles and by solid phase peptide synthesis, have catalytic activities, hydrolyzing peptide bonds in a natural protein, bovine serum albumin. These experimental results support the [GADV]-protein world hypothesis for the origin of life.
http://onlinelibrary.wiley.com.sci-hub.cc/doi/10.1002/tcr.20037/full
http://reasonandscience.heavenforum.org/t2468-current-origin-of-life-proposals
Regularly science journals and papers come up with new OOL ( origin of life ) scenarios.
1. The Emergence of Life as a First-Order Phase Transition
2. Molecules assemble in water, hint at origins of life
3. Meteorite Chemicals May Have Started Life on Earth—and Space
4. Thermodynamic origin of life
5. Life on Earth may have begun as dividing droplets
6. Hydrothermal vent models transform the origins of life from unlikely to near-inevitable.
7. The origins of life -- the 'protein interaction world' hypothesis
8. Primordial soup hypothesis
9. Electric Spark hypothesis
10. The minimotif synthesis hypothesis for the origin of life
11. The Oparin-Haldane Hypothesis
12. Origin of Life: The Heterotroph Hypothesis
13. Bubbles May Have Speeded Life's Origins on Earth
14. The Origin Of Life Dual Origin Hypothesis
15. Thermodynamic dissipation theory for the origin of life
16. Protein World Hypothesis on the Origin of Life
17. The Zinc world hypothesis
18. Origin of Life - The Sweet Crystal Hypothesis
19. Pyrite formation, the first energy source for life: a hypothesis
20. Hypothesis: the origin of life in a hydrogel environment
21. Submarine hot springs and the origin of life
22. Organic Aerosols and the Origin of Life: An Hypothesis
23. Thermoreduction, a hypothesis for the origin of prokaryotes
24. The [GADV]‐protein world hypothesis
25. The RNA first hypothesis
26. The metabolism first hypothesis
http://www.molevol.de/gallery/Origin-of-life_high.mp4
Serpintinisation
Serpentinization is a process whereby rock (usually ultramafic) is changed, with the addition of water into the crystal structure of the minerals found in the rock.
Transition metal sulfides
From the biological side, many phylogenomic studies conclude that clades exclusive to hydrothermal vents are the deepest branches in the tree of life. Further, most metabolic enzymes that catalyze anaerobic reactions with small gas molecules depend on transition metal sulfide clusters that have been noted to resemble minerals common to vents
The emergence of life from iron monosulphide bubbles at a submarine hydrothermal redox and pH front
Life on Earth may have begun as dividing droplets
In a primordial soup on ancient Earth, droplets of chemicals may have paved the way for the first cells. Shape-shifting droplets split, grow and split again in new computer simulations. The result indicates that simple chemical blobs can exhibit replication, one of the most basic properties of life, physicist Rabea Seyboldt of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, reported March 16 at a meeting of the American Physical Society.
https://www.sciencenews.org/article/life-earth-may-have-begun-dividing-droplets
Universal ancestor of all life on Earth was only half alive
One characteristic of almost all living cells is that they pump ions across a membrane to generate an electrochemical gradient, then use that gradient to make the energy-rich molecule ATP. Martin’s results suggest LUCA could not generate such a gradient but could harness an existing one to make ATP.
That fits in beautifully with the idea that the first life got its energy from the natural gradient between vent water and seawater, and so was bound to these vents. Only later did the ability to generate gradients evolve, allowing life to break away from the vents on at least two occasions – one giving rise to the first archaea, the other to bacteria.
https://www.newscientist.com/article/2098564-universal-ancestor-of-all-life-on-earth-was-only-half-alive/
The Emergence of Life as a First-Order Phase Transition
March 1, 2017
Here we present a model for the emergence of life in which replicators are explicitly coupled to their environment through the recycling of a finite supply of resources. The model exhibits a dynamic, first-order phase transition from nonlife to life, where the life phase is distinguished by selection on replicators. We show that environmental coupling plays an important role in the dynamics of the transition. The transition corresponds to a redistribution of matter in replicators and their environment, driven by selection on replicators, exhibiting an explosive growth in diversity as replicators are selected.
http://online.liebertpub.com/doi/abs/10.1089/ast.2016.1481?journalCode=ast&#utm_source=ETOC&utm_medium=email&utm_campaign=ast
Molecules assemble in water, hint at origins of life
February 20, 2013
Researchers are exploring an alternate theory for the origin of RNA: they think the RNA bases may have evolved from a pair of molecules distinct from the bases we have today. This theory looks increasingly attractive, as researchers were able to achieve efficient, highly ordered self-assembly in water with small molecules that are similar to the bases of RNA.
https://www.sciencedaily.com/releases/2013/02/130220123332.htm
Meteorite Chemicals May Have Started Life on Earth—and Space
April 16, 2015
https://www.scientificamerican.com/article/meteorite-chemicals-may-have-started-life-on-earth-and-space/
The molecules that kick-started life on primordial Earth could have been made in space and delivered by meteorites, according to researchers in Italy. The group synthesised sugars, amino acids and nucleobases with nothing more than formamide, meteorite material and the power of a simulated solar wind, replicating a process they believe cooked up a prebiotic soup long before life existed on Earth.
NASA Has Found The Ingredients For Life On Saturn’s Moon Enceladus
(Reuters) – Ice plumes shooting into space from Saturn’s ocean-bearing moon Enceladus contain hydrogen from hydrothermal vents, an environment that some scientists believe led to the rise of life on Earth, research published on Thursday showed.The discovery makes Enceladus the only place beyond Earth where scientists have found direct evidence of a possible energy source for life, according to the findings in the journal Science.Similar conditions, in which hot rocks meet ocean water, may have been the cradle for the appearance of microbial life on Earth more than 4 billion years ago.
https://www.galaxymonitor.com/nasa-has-found-the-ingredients-for-life-on-saturns-moon-enceladus/
Thermodynamic origin of life
9 September 2010
Understanding the thermodynamic function of life may shed light on its origin. Life, as are all irreversible processes, is contingent on entropy production. Entropy production is a measure of the rate of the tendency of Nature to explore available microstates. The most important irreversible process generating entropy in the biosphere, and thus facilitating this exploration, is the absorption and transformation of sunlight into heat. Here we hypothesize that life began, and persists today, as a catalyst for the absorption and dissipation of sunlight at the surface of shallow seas. The resulting heat is then efficiently harvested by other irreversible processes such as the water cycle, hurricanes, and ocean and wind currents. RNA and DNA are the most efficient of all known molecules for absorbing the intense ultraviolet light that could have penetrated the dense early atmosphere, and are remarkably rapid in transforming this light into heat in the presence of liquid water. From this perspective, the origin and evolution of life, inseparable from water and the water cycle, can be understood as resulting from the natural thermodynamic imperative of increasing the entropy production of the Earth in its interaction with its solar environment. A mechanism is proposed for the reproduction of RNA and DNA without the need for enzymes, promoted instead through UV light dissipation and the ambient conditions of prebiotic Earth.
https://arxiv.org/pdf/0907.0042.pdf
The Emergence of Cells During the Origin of Life
Science 08 Dec 2006:
simple physicochemical properties of elementary protocells can give rise to essential cellular behaviors, including primitive forms of Darwinian competition and energy storage. Such preexisting, cooperative interactions between the membrane and encapsulated contents could greatly simplify the transition from replicating molecules to true cells. They also suggest intriguing possibilities for further investigation. For example, a corollary of vesicle competition is that a charged genetic polymer, such as nucleic acid, would be much more effective at driving membrane uptake than an electrically neutral polymer, because most of the osmotic pressure is due to counterions associated with the charged polymer. Could this influence the natural selection of the genetic material itself? Furthermore, competition for membrane molecules would favor stabilized membranes, suggesting a selective advantage for the evolution of cross-linked fatty acids (e.g., di- and triglycerides) and even the phospholipids of today. Greater membrane stability leads to decreased dynamics, however, and the evolutionary solutions to this problem (e.g., permeases, synthetic enzymes) could cause a “snowball” effect on the complexity of early life (16). Exploration of these minimal systems promises to lead to more exciting insights into the origins of biological complexity.
http://science.sciencemag.org/content/314/5805/1558.full?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=irene%20chen&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT
Chemists may be zeroing in on chemical reactions that sparked the first life
By Robert F. ServiceMay. 19, 2017 , 6:00 AM
DNA is better known, but many researchers today believe that life on Earth got started with its cousin RNA, because that nucleic acid can act as both a repository of genetic information and a catalyst to speed up biochemical reactions. But those favoring this “RNA world” hypothesis have struggled for decades to explain how the molecule’s four building blocks could have arisen from the simpler compounds present during our planet’s early days. Now, chemists have identified simple reactions that, using the raw materials on early Earth, can synthesize close cousins of all four building blocks. The resemblance isn’t perfect, but it suggests scientists may be closing in on a plausible scenario for how life on Earth began.
RNA’s four building blocks are called nucleotides. Each is composed of ribose, a ring-shaped sugar molecule, connected to one of four different ring-shaped “bases,” adenine (A), guanine (G), cytosine (C), and uracil (U). C and U are structurally similar to each other and collectively known as pyrimidines, whereas A and G resemble each other and are known as purines. In 2009, researchers led by Matthew Powner and John Sutherland at the Medical Research Council in Cambridge, U.K., came up with the first plausible chemical reactions that could have synthesized pyrimidines on early Earth. But very different reactions, in different conditions, seemed necessary to make purines. That begged the question of how all four nucleotides could have wound up in the same place to give rise to the first “living” RNA molecules.
http://www.sciencemag.org/news/2017/05/chemists-may-be-zeroing-chemical-reactions-sparked-first-life?utm_source=newsfromscience&utm_medium=facebook-text&utm_campaign=firstlife-13132
Life on Earth may have begun as dividing droplets
In a primordial soup on ancient Earth, droplets of chemicals may have paved the way for the first cells. Shape-shifting droplets split, grow and split again in new computer simulations. The result indicates that simple chemical blobs can exhibit replication, one of the most basic properties of life, physicist Rabea Seyboldt of the Max Planck Institute for the Physics of Complex Systems in Dresden, Germany, reported March 16 at a meeting of the American Physical Society.
Within a liquid, small droplets of particular chemicals can separate out, like beads of oil in water. Such globules typically remain spherical, growing as they merge with other drops. But in simulations, Seyboldt and colleagues found that droplets might behave in a counterintuitive way under certain conditions, elongating and eventually dividing into two.
https://www.sciencenews.org/article/life-earth-may-have-begun-dividing-droplets?tgt=nr
Hydrothermal vent models transform the origins of life from unlikely to near-inevitable.
Evolution only seems to move toward greater order; in the larger scheme, it’s downhill all the way. Vent models posit that given the initial conditions, the emergence of life was not a near-miracle. It was inevitable.
http://nautil.us/issue/37/currents/the-fly-in-the-primordial-soup
The origins of life -- the 'protein interaction world' hypothesis: protein interactions were the first form of self-reproducing life and nucleic acids evolved later as memory molecules.
The 'protein interaction world' (PIW) hypothesis of the origins of life assumes that life emerged as a self-reproducing and expanding system of protein interactions. In mainstream molecular biology, 'replication' refers to the material copying of molecules such as nucleic acids. However, PIW is conceptualized as an abstract communication system constituted by the interactions between proteins, in which 'replication' happens at the level of self-reproduction of these interactions between proteins.
https://www.ncbi.nlm.nih.gov/pubmed/15694682
Primordial soup hypothesis
Life on Earth began more than 3 billion years ago, evolving from the most basic of microbes into a dazzling array of complexity over time. But how did the first organisms on the only known home to life in the universe develop from the primordial soup? One theory involved a "shocking" start. Another idea is utterly chilling. And one theory is out of this world! Inside you'll learn just how mysterious this all is, as we reveal the different scientific theories on the origins of life on Earth.
https://www.livescience.com/13363-7-theories-origin-life.html
Electric Spark hypothesis
Lightning may have provided the spark needed for life to begin.
Electric sparks can generate amino acids and sugars from an atmosphere loaded with water, methane, ammonia and hydrogen, as was shown in the famous Miller-Urey experiment reported in 1953, suggesting that lightning might have helped create the key building blocks of life on Earth in its early days. Over millions of years, larger and more complex molecules could form. Although research since then has revealed the early atmosphere of Earth was actually hydrogen-poor, scientists have suggested that volcanic clouds in the early atmosphere might have held methane, ammonia and hydrogen and been filled with lightning as well.
Or could simple clay have fueled life’s beginning? Read on to find out.
Electric Spark Lightning may have provided the spark needed for life to begin. Electric sparks can generate amino acids and sugars from an atmosphere loaded with water, methane, ammonia and hydrogen, as was shown in the famous Miller-Urey experiment reported in 1953, suggesting that lightning might have helped create the key building blocks of life on Earth in its early days. Over millions of years, larger and more complex molecules could form. Although research since then has revealed the early atmosphere of Earth was actually hydrogen-poor, scientists have suggested that volcanic clouds in the early atmosphere might have held methane, ammonia and hydrogen and been filled with lightning as well. Or could simple clay have fueled life’s beginning? Read on to find out.
https://www.livescience.com/13363-7-theories-origin-life.html
The minimotif synthesis hypothesis for the origin of life
Several theories for the origin of life have gained widespread acceptance, led by primordial soup, chemical evolution, metabolism first, and the RNA world. However, while new and existing theories often address a key step, there is less focus on a comprehensive abiogenic continuum leading to the last universal common ancestor. Herein, I present the “minimotif synthesis” hypothesis unifying select origin of life theories with new and revised steps. The hypothesis is based on first principles, on the concept of selection over long time scales, and on a stepwise progression toward complexity. The major steps are the thermodynamically-driven origination of extant molecular specificity emerging from primordial soup leading to the rise of peptide catalysts, and a cyclic feed-forward catalytic diversification of compounds and peptides in the primordial soup. This is followed by degenerate, semi-partially conservative peptide replication to pass on catalytic knowledge to progeny protocells. At some point during this progression, the emergence of RNA and selection could drive the separation of catalytic and genetic functions, allowing peptides and proteins to permeate the catalytic space, and RNA to encode higher fidelity information transfer. Translation may have emerged from RNA template driven organization and successive ligation of activated amino acids as a predecessor to translation.
https://oatext.com/The-minimotif-synthesis-hypothesis-for-the-origin-of-life.php
The Oparin-Haldane Hypothesis
In the early decades of the 20th century, Aleksandr Oparin (in 1924), and John Haldane (in 1929, before Oparin's first book was translated into English), independently suggested that if the primitive atmosphere was reducing (as opposed to oxygen-rich), and if there was an appropriate supply of energy, such as lightning or ultraviolet light, then a wide range of organic compounds might be synthesised.
Oparin suggested that the organic compounds could have undergone a series of reactions leading to more and more complex molecules. He proposed that the molecules formed colloid aggregates, or 'coacervates', in an aqueous environment. The coacervates were able to absorb and assimilate organic compounds from the environment in a way reminiscent of metabolism. They would have taken part in evolutionary processes, eventually leading to the first lifeforms.
Haldane's ideas about the origin of life were very similar to Oparin's. Haldane proposed that the primordial sea served as a vast chemical laboratory powered by solar energy. The atmosphere was oxygen free, and the combination of carbon dioxide, ammonia and ultraviolet radiation gave rise to a host of organic compounds. The sea became a 'hot dilute soup' containing large populations of organic monomers and polymers. Haldane envisaged that groups of monomers and polymers aquired lipid membranes, and that further developments eventually led to the first living cells.
Haldane coined the term 'prebiotic soup', and this became a powerful symbol of the Oparin-Haldane view of the origin of life.
http://www.simsoup.info/Origin_Landmarks_Oparin_Haldane.html
Origin of Life: The Heterotroph Hypothesis
The anaerobic metabolic processes of the heterotrophs released carbon dioxide into the atmosphere, which allowed for the evolution of photosynthetic autotrophs, which could use light and CO2 to produce their own food. The autotrophs released oxygen into the atmosphere. For most of the original anaerobic heterotrophs, oxygen proved poisonous. The few heterotrophs that survived the change in environment generally evolved the capacity to carry out aerobic respiration. Over the subsequent billions of years, the aerobic autotrophs and heterotrophs became the dominant life-forms on the planet and evolved into all of the diversity of life now visible on Earth.
http://www.sparknotes.com/testprep/books/sat2/biology/chapter8section1.rhtml
Bubbles May Have Speeded Life's Origins on Earth
The role of bubbles in the creation of life on earth is one of the newest approaches to solving the scientific mystery that is probably second in importance only to the problem of how the universe itself began.
No one is suggesting that bubbles might explain everything. But in a new hypothesis receiving close attention, the multitudes of bubbles forming on the surface of the primordial seas must have collected chemicals and concentrated them for synthesis into complex molecules. Eventually, through multistage reactions constantly repeated by uncounted generations of bubbles, the molecules grew in size and ambition, ready for the transition to living, reproducing cells.
http://www.nytimes.com/1993/07/06/science/bubbles-may-have-speeded-life-s-origins-on-earth.html?pagewanted=all
The Origin Of Life Dual Origin Hypothesis
According to the dual origin hypothesis, the cerebral cortex of higher mammals evolved from two primordial brain structures, the amygdala and hippocampal formation. This developmental process defines the orderly principles of cortical connectivity and gives rise to functionally distinct ventral and dorsal systems within the cerebrum. This paper reviews the basic features of the dual origin theory. This model is then applied to understanding symptom production in a number of psychiatric illnesses, with particular reference to recent structural and functional imaging studies. In this paper I propose that psychiatric symptoms can be conceptualized as arising from abnormal processing within dorsal (time-space-motility) or ventral (meaning-motivation) systems, or from a disturbance in the functional interaction/balance between them. Within this framework, one can identify symptom-specific correlations that cross-traditional diagnostic boundaries, as well as potential mechanisms that may explain biologically valid diagnostic entities. Integrating evolutionary, connectional and functional bases across multiple species, the dual origin hypothesis offers a powerful neural systems model to help organize our understanding of psychiatric illness, therein suggesting novel approaches to diagnosis, prevention and treatment.
https://www.ncbi.nlm.nih.gov/pubmed/16356547
Thermodynamic dissipation theory for the origin of life
Understanding the thermodynamic function of life may shed light on its origin. Life, as are all irreversible processes, is contingent on entropy production. Entropy production is a measure of the rate of the tendency of Nature
to explore available microstates. The most important irreversible process generating entropy in the biosphere and, thus, facilitating this exploration, is the absorption and transformation of sunlight into heat. Here we hypothesize that life began, and persists today, as a catalyst for the absorption and dissipation of sunlight on the surface of Archean seas. The resulting heat could then be efficiently harvested by other irreversible processes such as the water cycle, hurricanes, and ocean and wind currents. RNA and DNA are the most efficient of all known molecules for absorbing the intense ultraviolet light that penetrated the dense early atmosphere and are remarkably rapid in transforming this light into heat in the presence of liquid water. From this perspective, the origin and evolution of life, inseparable from water and the water cycle, can be understood as resulting from the natural thermodynamic imperative of increasing the entropy production of the Earth in its interaction with its solar environment. A mechanism is proposed for the reproduction of RNA and DNA without the need for enzymes, promoted instead through UV light dissipation and diurnal temperature cycling of the Archean sea-surface.
http://www.earth-syst-dynam.net/2/37/2011/esd-2-37-2011.pdf
Protein World Hypothesis on the Origin of Life
RNA world hypothesis is widely accepted still now, as an idea by which the origin of life might be explained. But, there are many weak points in the hypothesis. In contrast, I have proposed a more reasonable [GADV]-protein world hypothesis or GADV hypothesis, suggesting that life originated from the protein world, which was formed by pseudo-replication of [GADV]-proteins. In this communication, I will discuss about the origin of life from the point of view of the GADV hypothesis.
https://link.springer.com/article/10.1007/s11084-014-9383-4
The Zinc world hypothesis
The suggested "Zn world" scenario identifies the geological conditions under which photosynthesizing ZnS edifices of hydrothermal origin could emerge and persist on primordial Earth, includes a mechanism of the transient storage and utilization of solar light for the production of diverse organic compounds, and identifies the driving forces and selective factors that could have promoted the transition from the first simple, photostable polymers to more complex living organisms.
https://biologydirect.biomedcentral.com/articles/10.1186/1745-6150-4-26
Origin of Life - The Sweet Crystal Hypothesis
When Cairns-Smith formulated his theory of crystalline ancestry - which accounts for the main mechanism by which life can form from inorganic precursors - he was percieved as not having provided a very detailed scenario for the introduction of organic material. Rather he showed how life can form, demonstrated that genetic takeovers were possible, illustrated that there would be selection pressure for carbon-based systems once they arose, and then suggested that the rest of the story was simply a matter for natural selection.
This state of affairs apparently left some of those who had not read Genetic Takeover unsatisfied. They felt as though the origin of their sort of life had not really been explained at all. They did not see where nucleic acid came from - and the origin of cell walls was still a mystery.
While some of the details have no-doubt been lost to history, it seems that some of the subsequent paths in the early evolution of organisms can be identified with a reasonable level of confidence. Even where this is not the case, it may prove helpful to identify in some detail at least one plausible scenario by which evolution can lead away from crystalline organisms, towards ones more easily recognisable as our ancestors.
http://originoflife.net/sweet_crystal/
Pyrite formation, the first energy source for life: a hypothesis
I here propose a new energy source for an autotrophic origin of life. It is the exergonic formation of pyrite from hydrogen sulfide and ferrous ions
http://www.sciencedirect.com.sci-hub.cc/science/article/pii/S0723202088800018
Hypothesis: the origin of life in a hydrogel environment
A hypothesis is proposed that the first cell(s) on the Earth assembled in a hydrogel environment. Gel environments are capable of retaining water, oily hydrocarbons, solutes, and gas bubbles, and are capable of carrying out many functions, even in the absence of a membrane. Thus, the gel-like environment may have conferred distinct advantages for the assembly of the first cell(s).
http://www.sciencedirect.com.sci-hub.cc/science/article/pii/S0079610704000999
Submarine hot springs and the origin of life
The discovery of hydrothermal vents at oceanic ridge crests and the appreciation of their importance in the element balance of the oceans is one of the main recent advances in marine geochemistry1. It is likely that vents were present in the oceans of the primitive Earth because the process of hydrothermal circulation probably began early in the Earth's history2.
http://www.nature.com.ololo.sci-hub.cc/nature/journal/v334/n6183/abs/334609a0.html
Organic Aerosols and the Origin of Life: An Hypothesis
Recent experimental work has verified the prediction that marine aerosols could have an exterior film of amphiphiles; palmitic, stearic and oleic acids were predominant. Thermodynamic analysis has revealed that such aerosols are energetically capable of asymmetric division. In a prebiotic terrestrial environment, one of the products of such aerosol fission would have been bacterially sized (microns), the other would have been virally sized (tens of nanometers). Plausible avenues for chemical differentiation between the two particles are discussed, and the probabilities for the transition from geochemistry to biochemistry updated in light of recent palaeo fossil studies.
http://link.springer.com.ololo.sci-hub.cc/article/10.1023%2FB%3AORIG.0000009828.40846.b3?LI=true
Thermoreduction, a hypothesis for the origin of prokaryotes
https://www.researchgate.net/profile/Patrick_Forterre2/publication/15551510_Thermoreduction_a_hypothesis_for_the_origin_of_prokaryotes/links/0f317536bc0eb3e30e000000.pdf
The [GADV]‐protein world hypothesis
Based on the fact that RNA has not only a genetic function but also a catalytic function, the RNA world theory on the origin of life was first proposed about 20 years ago. The theory assumes that RNA was amplified by self-replication to increase RNA diversity on the primitive earth. Since then, the theory has been widely accepted as the most likely explanation for the emergence of life. In contrast, we reached another hypothesis, the [GADV]-protein world hypothesis, which is based on pseudo-replication of [GADV]-proteins. We reached this hypothesis during studies on the origins of genes and the genetic code, where [G], [A], [D], and [V] refer to Gly, Ala, Asp, and Val, respectively. In this review, possible steps to the emergence of life are discussed from the standpoint of the [GADV]-protein world hypothesis, comparing it in parallel with the RNA world theory. It is also shown that [GADV]-peptides, which were produced by repeated dry-heating cycles and by solid phase peptide synthesis, have catalytic activities, hydrolyzing peptide bonds in a natural protein, bovine serum albumin. These experimental results support the [GADV]-protein world hypothesis for the origin of life.
http://onlinelibrary.wiley.com.sci-hub.cc/doi/10.1002/tcr.20037/full
