Origins of Life: The Protein Folding Problem all over again?

How did specific useful protein sequences arise from simpler molecules at the origin of life? This seemingly needle-in-a-haystack problem has remarkably close resemblance to the old Protein Folding Problem, for which the solution is now known from statistical physics. Based on the logic that Origins must have come only after there was an operative evolution mechanism-which selects on phenotype, not genotype-we give a perspective that proteins and their folding processes are likely to have been the primary driver of the early stages of the origin of life.

The evolutionary arch of bioenergetics from prebiotic mechanisms to the emergence of a cellular respiratory chain.

This article proposes an evolutionary trajectory for the development of biological energy producing systems. Six main stages of energy producing system evolution are described, from early evolutionary pyrite-pulled mechanism through the Last Universal Common Ancestor (LUCA) to contemporary systems. We define the Last Pure Chemical Entity (LPCE) as the last completely non-enzymatic entity. LPCE could have had some life-like properties, but lacked genetic information carriers, thus showed greater instability and environmental dependence than LUCA. A double bubble model is proposed for compartmentalization and cellularization as a prerequisite to both highly efficient protein synthesis and transmembrane ion-gradient. The article finds that although LUCA predominantly functioned anaerobically, it was a non-exclusive anaerobe, and sulfur dominated metabolism preceded phosphate dominated one.

Understanding the Role of Layered Minerals in the Emergence and Preservation of Proto-Proteins and Detection of Traces of Early Life.

ConspectusThe origin of life remains one of the most profound mysteries in science. Over millennia, theories have evolved, yet the question persists: How did life emerge from inanimate matter? At its core, the study of life's origin offers insights into our place in the universe and the nature of life itself. By delving into the chemical and geological processes that led to life's emergence, scientists gain a deeper understanding of the fundamental principles that govern living systems. This knowledge not only expands our scientific understanding but also has profound implications for fields ranging from astrobiology to synthetic biology.This research employs a multidisciplinary approach, combining a diverse array of techniques, from space missions to wet laboratory experiments to theoretical modeling. Investigations into the formation of the first proto-biomolecules are tailored to explore both the complex molecular processes that underpin life and the geological contexts in which these processes may have occurred. While laboratory experiments are aimed at mimicking the processes of early planets, not every process and sample is attainable. To this end, we demonstrate the use of molecular modeling techniques to complement experimental efforts and extraterrestrial missions. The simulations enable researchers to test hypotheses and explore scenarios that are difficult or impossible to replicate in the laboratory, bridging gaps in our understanding of prebiotic processes across vast time and space scales.Minerals, particularly layered structures like clays and hydrotalcites, play diverse and pivotal roles in the origin of life. They concentrate organic species, catalyze polymerization reactions (such as peptide formation), and provide protective environments for the molecules. Minerals have also been suggested to have acted as primitive genetic materials. Nevertheless, they may lack the ability for long-term information replication. Instead, we suggest that minerals may act as transcribers of information encoded in environmental cyclic phenomena, such as tidal or seasonal changes. We argue that extensive protection of the produced polymer will immobilize it, making it inactive for any further function. Therefore, in order to generate a functional polymer, it is essential that it remains mobile and chemically active. Furthermore, we suggest a route to the identification of pseudobiosignatures, a polymer that was polymerized on the same mineral surface and consequently retained through overprotection.This Account presents a comprehensive evaluation of the current understanding of the role of layered mineral surfaces on life's origin and biosignature preservation. It highlights the complexity of mineral-organic interactions and proposes pathways for proto-biomolecule emergence and methods for identifying and interpreting potential biosignatures. Ultimately, the quest to uncover the origin of life continues to drive scientific exploration and innovation, offering profound insights into the fundamental nature of existence and our place in the universe.

Kinetic Resolution as a General Approach to Enantioenrichment in Prebiotic Chemistry.

ConspectusThe origin of the single chirality of the chemical building blocks of life remains an intriguing topic of research, even after decades of experimental and theoretical work proposing processes that may break symmetry and induce chiral amplification, a term that may be defined as the enhancement of enantiomeric excess starting from prochiral substrates or from a racemic mixture or a small imbalance between enantiomers. Studies aimed at understanding prebiotically plausible pathways to these molecules have often neglected the issue of chirality, with a focus on the stereochemical direction of these reactions generally being pursued after reaction discovery. Our work has explored how the stereochemical outcome for the synthesis of amino acids and sugars might be guided to rationalize the origin of biological homochirality. The mechanistic interconnection between enantioenrichment in these two groups of molecules provides insights concerning the handedness extant in modern biology. In five separate examples involving the synthesis of life's building blocks, including sugars, RNA precursors, amino acids, and peptides, kinetic resolution emerges as a key protocol for enantioenrichment from racemic molecules directed by chiral source molecules. Several of these examples involve means not only for chiral amplification but also symmetry breaking and chirality transfer across a range of racemic monomer molecules. Several important implications emerge from these studies: one, kinetic resolution of the primordial chiral sugar, glyceraldehyde, plays a key role in a number of different prebiotically plausible reactions; two, the emergence of homochirality in sugars and amino acids is inherently intertwined, with clear synergy between the biological hand of each molecule class; three, the origin story for the homochirality of enzymes and modern metabolism points toward kinetic resolution of racemic amino acids in networks that later evolved to include sophisticated and complete catalytic and co-catalytic cycles; four, a preference for heterochiral ligation forming product molecules that cannot lead to biologically competent polymers can in fact be a driving force for a route to homochiral polymer chains; and five, enantioenrichment in complex mixtures need not be addressed one compound at a time, because kinetic resolution induces symmetry breaking and chirality transfer that may lead to general protocols rather than specific cases tailored to each individual molecule. Such chirality transfer mechanisms perhaps presage strategies utilized in modern biology.Our latest work extends the study of monomer enantioenrichment to the ligation of these molecules into the extended homochiral chains leading to the complex polymers of modern biology. A central theme in all of these reactions is the key role that kinetic resolution of a racemic mixture of amino acids or sugars plays in enabling enantioenrichment under prebiotically plausible conditions. This work has uncovered important trends in symmetry breaking, chirality transfer, and chiral amplification. Kinetic resolution of racemic mixtures emerges as a general solution for chiral amplification in prebiotic chemistry, leading to the single chirality of complex biological molecules and genetic polymers.

A Bayesian Analysis of the Probability of the Origin of Life Per Site Conducive to Abiogenesis.

The emergence of life from nonlife, or abiogenesis, remains a fundamental question in scientific inquiry. In this article, we investigate the probability of the origin of life (per conducive site) by leveraging insights from Earth's environments. If life originated endogenously on Earth, its existence is indeed endowed with informative value, although the interpretation of the attendant significance hinges critically upon prior assumptions. By adopting a Bayesian framework, for an agnostic prior, we establish a direct connection between the number of potential locations for abiogenesis on Earth and the probability of life's emergence per site. Our findings suggest that constraints on the availability of suitable environments for the origin(s) of life on Earth may offer valuable insights into the probability of abiogenesis and the frequency of life in the universe.

Peptides En Route from Prebiotic to Biotic Catalysis.

ConspectusIn the quest to understand prebiotic catalysis, different molecular entities, mainly minerals, metal ions, organic cofactors, and ribozymes, have been implied as key players. Of these, inorganic and organic cofactors have gained attention for their ability to catalyze a wide array of reactions central to modern metabolism and frequently participate in these reactions within modern enzymes. Nevertheless, bridging the gap between prebiotic and modern metabolism remains a fundamental question in the origins of life.In this Account, peptides are investigated as a potential bridge linking prebiotic catalysis by minerals/cofactors to enzymes that dominate modern life's chemical reactions. Before ribosomal synthesis emerged, peptides of random sequences were plausible on early Earth. This was made possible by different sources of amino acid delivery and synthesis, as well as their condensation under a variety of conditions. Early peptides and proteins probably exhibited distinct compositions, enriched in small aliphatic and acidic residues. An increase in abundance of amino acids with larger side chains and canonical basic groups was most likely dependent on the emergence of their more challenging (bio)synthesis. Pressing questions thus arise: how did this composition influence the early peptide properties, and to what extent could they contribute to early metabolism?Recent research from our group and colleagues shows that highly acidic peptides/proteins comprising only the presumably "early" amino acids are in fact competent at secondary structure formation and even possess adaptive folding characteristics such as spontaneous refoldability and chaperone independence to achieve soluble structures. Moreover, we showed that highly acidic proteins of presumably "early" composition can still bind RNA by utilizing metal ions as cofactors to bridge carboxylate and phosphoester functional groups. And finally, ancient organic cofactors were shown to be capable of binding to sequences from amino acids considered prebiotically plausible, supporting their folding properties and providing functional groups, which would nominate them as catalytic hubs of great prebiotic relevance.These findings underscore the biochemical plausibility of an early peptide/protein world devoid of more complex amino acids yet collaborating with other catalytic species. Drawing from the mechanistic properties of protein-cofactor catalysis, it is speculated here that the early peptide/protein-cofactor ensemble could facilitate a similar range of chemical reactions, albeit with lower catalytic rates. This hypothesis invites a systematic experimental test.Nonetheless, this Account does not exclude other scenarios of prebiotic-to-biotic catalysis or prioritize any specific pathways of prebiotic syntheses. The objective is to examine peptide availability, composition, and functional potential among the various factors involved in the emergence of early life.

Evolutionary Abilities of Minimalistic Physicochemical Models of Life Processes.

The ability of living organisms to persist, grow, evolve and invade environments seemingly challenges physical laws. Emerging Autonomous Systems representing autocatalytic cycles constituted of energized components in a state of Dynamic Kinetic Stability feature some of these properties. These simple theoretical models can grow, can be transferred but need an initiation to emerge and can collapse. Moreover, they can undergo kinetic selection in a way consistent with Darwinian behaviour, though they lack the ability to undergo change. The mere existence of these systems and their open-ended growth potential are proposed to constitute a transmissible factor of a non-coded kind. The onset and selection of epigenetic factors may therefore have preceded that of genetic polymers. Here is addressed the question of how these systems may arise from the diversity exhibited by abiotic organic matter, sometimes associated with intractable mixtures, which may actually be useful in providing initiators. The Darwinian description of evolution may therefore be merged without critical discontinuity within an origin scenario. Accordingly, such a theory would rests solely on physicochemical laws beginning with the potential of emerging autonomous systems to compete and invade the space dimension, and to further develop along other available dimensions including variability and, possibly, cognition.

Ichthyosporea: a window into the origin of animals.

Ichthyosporea is an underexplored group of unicellular eukaryotes closely related to animals. Thanks to their phylogenetic position, genomic content, and development through a multinucleate coenocyte reminiscent of some animal embryos, the members of Ichthyosporea are being increasingly recognized as pivotal to the study of animal origins. We delve into the existing knowledge of Ichthyosporea, identify existing gaps and discuss their life cycles, genomic insights, development, and potential to be model organisms. We also discuss the underestimated diversity of ichthyosporeans, based on new environmental data analyses. This review will be an essential resource for researchers venturing into the study of ichthyosporeans.

The astrochemical evolutionary traits of phospholipid membrane homochirality.

Compartmentalization is crucial for the evolution of life. Present-day phospholipid membranes exhibit a high level of complexity and species-dependent homochirality, the so-called lipid divide. It is possible that less stable, yet more dynamic systems, promoting out-of-equilibrium environments, facilitated the evolution of life at its early stages. The composition of the preceding primitive membranes and the evolutionary route towards complexity and homochirality remain unexplained. Organics-rich carbonaceous chondrites are evidence of the ample diversity of interstellar chemistry, which may have enriched the prebiotic milieu on early Earth. This Review evaluates the detections of simple amphiphiles - likely ancestors of membrane phospholipids - in extraterrestrial samples and analogues, along with potential pathways to form primitive compartments on primeval Earth. The chiroptical properties of the chiral backbones of phospholipids provide a guide for future investigations into the origins of phospholipid membrane homochirality. We highlight a plausible common pathway towards homochirality of lipids, amino acids, and sugars starting from enantioenriched monomers. Finally, given their high recalcitrance and resistance to degradation, lipids are among the best candidate biomarkers in exobiology.

Prebiotic N-(2-Aminoethyl)-Glycine (AEG)-Assisted Synthesis of Proto-RNA?

Quantum mechanical calculations are used to explore the thermodynamics of possible prebiotic synthesis of the building blocks of nucleic acids. Different combinations of D-ribofuranose (Ribf) and N-(2-aminoethyl)-glycine (AEG) (trifunctional connectors (TCs)); the nature of the Ribf, its anomeric form, and its ring puckering (conformation); and the nature of the nucleobases (recognition units (RUs)) are considered. The combinatorial explosion of possible nucleosides has been drastically reduced on physicochemical grounds followed by a detailed thermodynamic evaluation of alternative synthetic pathways. The synthesis of nucleosides containing N-(2-aminoethyl)-glycine (AEG) is predicted to be thermodynamically favored suggesting a possible role of AEG as a component of an ancestral proto-RNA that may have preceded today's nucleic acids. A new pathway for the building of free nucleotides (exemplified by 5'-uridine monophosphate (UMP)) and of AEG dipeptides is proposed. This new pathway leads to a spontaneous formation of free UMP assisted by an AEG nucleoside in an aqueous environment. This appears to be a workaround to the "water problem" that prohibits the synthesis of nucleotides in water.

Dynamics of the osmotic lysis of mineral protocells and its avoidance at the origins of life.

The osmotic rupture of a cell, its osmotic lysis or cytolysis, is a phenomenon that active biological cell volume regulation mechanisms have evolved in the cell membrane to avoid. How then, at the origin of life, did the first protocells survive prior to such active processes? The pores of alkaline hydrothermal vents in the oceans form natural nanoreactors in which osmosis across a mineral membrane plays a fundamental role. Here, we discuss the dynamics of lysis and its avoidance in an abiotic system without any active mechanisms, reliant upon self-organized behaviour, similar to the first self-organized mineral membranes within which complex chemistry may have begun to evolve into metabolism. We show that such mineral nanoreactors could function as protocells without exploding because their self-organized dynamics have a large regime in parameter space where osmotic lysis does not occur and homeostasis is possible. The beginnings of Darwinian evolution in proto-biochemistry must have involved the survival of protocells that remained within such a safe regime.

Reactions Driven by Primitive Nonbiological Polyesters.

ConspectusAll life on Earth is composed of cells, which are built from and run by biological reactions and structures. These reactions and structures are generally the result of action by cellular biomolecules, which are indispensable for the function and survival of all living organisms. Specifically, biological catalysis, namely by protein enzymes, but also by other biomolecules including nucleic acids, is an essential component of life. How the biomolecules themselves that perform biological catalysis came to exist in the first place is a major unanswered question that plagues researchers to this day, which is generally the focus of the origins of life (OoL) research field. Based on current knowledge, it is generally postulated that early Earth was full of a myriad of different chemicals, and that these chemicals reacted in specific ways that led to the emergence of biochemistry, cells, and later, life. In particular, a significant part of OoL research focuses on the synthesis, evolution, and function of biomolecules potentially present under early Earth conditions, as a way to understand their eventual transition into modern life. However, this narrative overlooks possibilities that other molecules contributed to the OoL, as while biomolecules that led to life were certainly present on early Earth, at the same time, other molecules that may not have strict, direct biological lineage were also widely and abundantly present. For example, hydroxy acids, although playing a role in metabolism or as parts of certain biological structures, are not generally considered to be as essential to modern biology as amino acids (a chemically similar monomer), and thus research in the OoL field tends to perhaps focus more on amino acids than hydroxy acids. However, their likely abundance on early Earth coupled with their ability to spontaneously condense into polymers (i.e., polyesters) make hydroxy acids, and their subsequent products, functions, and reactions, a reasonable target of investigation for prebiotic chemists. Whether "non-biological" hydroxy acids or polyesters can contribute to the emergence of life on early Earth is an inquiry that deserves attention within the OoL community, as this knowledge can also contribute to our understanding of the plausibility of extraterrestrial life that does not exactly use the biochemical set found in terrestrial organisms. While some demonstrations have been made with respect to compartment assembly, compartmentalization, and growth of primitive polyester-based systems, whether these "non-biological" polymers can contribute any catalytic function and/or drive primitive reactions is still an important step toward the development of early life. Here, we review research both from the OoL field as well as from industry and applied sciences regarding potential catalysis or reaction driven by "non-biological" polyesters in various forms: as linear polymers, as hyperbranched polyesters, and as membraneless microdroplets.

Circular at the very beginning: on the initial genomes in the RNA world.

It is likely that an RNA world existed in early life, when RNA played both the roles of the genome and functional molecules, thereby undergoing Darwinian evolution. However, even with only one type of polymer, it seems quite necessary to introduce a labour division concerning these two roles because folding is required for functional molecules (ribozymes) but unfavourable for the genome (as a template in replication). Notably, while ribozymes tend to have adopted a linear form for folding without constraints, a circular form, which might have been topologically hindered in folding, seems more suitable for an RNA template. Another advantage of involving a circular genome could have been to resist RNA's end-degradation. Here, we explore the scenario of a circular RNA genome plus linear ribozyme(s) at the precellular stage of the RNA world through computer modelling. The results suggest that a one-gene scene could have been 'maintained', albeit with rather a low efficiency for the circular genome to produce the ribozyme, which required precise chain-break or chain-synthesis. This strict requirement may have been relieved by introducing a 'noncoding' sequence into the genome, which had the potential to derive a second gene through mutation. A two-gene scene may have 'run well' with the two corresponding ribozymes promoting the replication of the circular genome from different respects. Circular genomes with more genes might have arisen later in RNA-based protocells. Therefore, circular genomes, which are common in the modern living world, may have had their 'root' at the very beginning of life.

How Droplets Can Accelerate Reactions─Coacervate Protocells as Catalytic Microcompartments.

ConspectusCoacervates are droplets formed by liquid-liquid phase separation (LLPS) and are often used as model protocells-primitive cell-like compartments that could have aided the emergence of life. Their continued presence as membraneless organelles in modern cells gives further credit to their relevance. The local physicochemical environment inside coacervates is distinctly different from the surrounding dilute solution and offers an interesting microenvironment for prebiotic reactions. Coacervates can selectively take up reactants and enhance their effective concentration, stabilize products, destabilize reactants and lower transition states, and can therefore play a similar role as micellar catalysts in providing rate enhancement and selectivity in reaction outcome. Rate enhancement and selectivity must have been essential for the origins of life by enabling chemical reactions to occur at appreciable rates and overcoming competition from hydrolysis.In this Accounts, we dissect the mechanisms by which coacervate protocells can accelerate reactions and provide selectivity. These mechanisms can similarly be exploited by membraneless organelles to control cellular processes. First, coacervates can affect the local concentration of reactants and accelerate reactions by copartitioning of reactants or exclusion of a product or inhibitor. Second, the local environment inside the coacervate can change the energy landscape for reactions taking place inside the droplets. The coacervate is more apolar than the surrounding solution and often rich in charged moieties, which can affect the stability of reactants, transition states and products. The crowded nature of the droplets can favor complexation of large molecules such as ribozymes. Their locally different proton and water activity can facilitate reactions involving a (de)protonation step, condensation reactions and reactions that are sensitive to hydrolysis. Not only the coacervate core, but also the surface can accelerate reactions and provides an interesting site for chemical reactions with gradients in pH, water activity and charge. The coacervate is often rich in catalytic amino acids and can localize catalysts like divalent metal ions, leading to further rate enhancement inside the droplets. Lastly, these coacervate properties can favor certain reaction pathways, and thereby give selectivity over the reaction outcome.These mechanisms are further illustrated with a case study on ribozyme reactions inside coacervates, for which there is a fine balance between concentration and reactivity that can be tuned by the coacervate composition. Furthermore, coacervates can both catalyze ribozyme reactions and provide product selectivity, demonstrating that coacervates could have functioned as enzyme-like catalytic microcompartments at the origins of life.

On the origin of life on earth.

The creation of the universe out of nothing (ex nihilo) is attributable to the eternal God. Would a direct divine intervention be needed for other singular events, such as the origin of life? Taking apart the human being, created to image and resemblance of God, we argue that current scientific knowledge allows us to rationally admit a continuity between the origins of the universe and the emergence of life on Earth. Although the irruption of living beings from inert matter is a leap or discontinuity in creation, a direct intervention of God would not be indispensable. The initial impulse of creation, with matter and energy in a space-time imbalance, could have triggered reactions between the different elements and a self-organization of metabolites, in accordance with natural physical-chemistry laws. This paradoxical increase of complexity ended with a transition from chemistry to biology. It happened when independence, metabolism, heritability, and life cycle took place in a protocellular unit. In this way, the emergence of life on earth could be part of an evolutionary dynamic of the timeless God's creative act.

Rethinking life and predicting its origin.

The definition, origin and recreation of life remain elusive. As others have suggested, only once we put life into reductionist physical terms will we be able to solve those questions. To that end, this work proposes the phenomenon of life to be the product of two dissipative mechanisms. From them, one characterises extant biological life and deduces a testable scenario for its origin. The proposed theory of life allows its replication, reinterprets ecological evolution and creates new constraints on the search for life.

The Origin of RNA and the Formose-Ribose-RNA Pathway.

Prebiotic pre-Darwinian reactions continued throughout biochemical or Darwinian evolution. Early chemical processes could have occurred on Earth between 4.5 and 3.6 billion years ago when cellular life was about to come into being. Pre-Darwinian evolution assumes the development of hereditary elements but does not regard them as self-organizing processes. The presence of biochemical self-organization after the pre-Darwinian evolution did not justify distinguishing between different types of evolution. From the many possible solutions, evolution selected from among those stable reactions that led to catalytic networks, and under gradually changing external conditions produced a reproducible, yet constantly evolving and adaptable, living system. Major abiotic factors included sunlight, precipitation, air, minerals, soil and the Earth's atmosphere, hydrosphere and lithosphere. Abiotic sources of chemicals contributed to the formation of prebiotic RNA, the development of genetic RNA, the RNA World and the initial life forms on Earth and the transition of genRNA to the DNA Empire, and eventually to the multitude of life forms today. The transition from the RNA World to the DNA Empire generated new processes such as oxygenic photosynthesis and the hierarchical arrangement of processes involved in the transfer of genetic information. The objective of this work is to unite earlier work dealing with the formose, the origin and synthesis of ribose and RNA reactions that were published as a series of independent reactions. These reactions are now regarded as the first metabolic pathway.

Evaluating Pigments as a Biosignature: Abiotic/Prebiotic Synthesis of Pigments and Pigment Mimics in Planetary Environments.

Pigments serve a multitude of functions in biology including light harvesting for photosynthesis, radiation protection, membrane support, and defense. The ubiquity of pigments-especially within extremophiles found in high-radiation, high-salinity, and dry environments-and their detectability via mission-ready techniques have elevated these molecules as promising targets in the search for evidence of life elsewhere. Moreover, the detection of pigments has been proposed as a "smoking gun" for extraterrestrial life as it has been suggested that these molecules cannot be generated abiotically. However, while pigments may hold promise as a biosignature, current understanding of their possible prebiotic origins remains understudied and uncertain. Better understanding of the abiotic synthesis of pigments is critical for evaluating the biogenicity of any pigment detected during missions, including by the Mars Perseverance rover or from returned samples. Compounding this uncertainty is the broad definition of pigment as it includes any compound capable of absorbing visible light and by itself does not specify a particular chemical motif. While not experimentally verified, there are promising prebiotic routes for generating pigments including hemes, chlorophylls, and carotenoids. Herein, we review the biochemistry of pigments, the inherent assumptions made when searching for these molecules in the field, their abiotic synthesis in industry and prebiotic reactions, prebiotically relevant molecules that can mimic their spectral signatures, and implications/recommendations for future work.

UV Transmission in Prebiotic Environments on Early Earth.

Ultraviolet (UV) light is likely to have played important roles in surficial origins of life scenarios, potentially as a productive source of energy and molecular activation, as a selective means to remove unwanted side products, or as a destructive mechanism resulting in loss of molecules/biomolecules over time. The transmission of UV light through prebiotic waters depends upon the chemical constituents of such waters, but constraints on this transmission are limited. Here, we experimentally measure the molar decadic extinction coefficients for a number of small molecules used in various prebiotic synthetic schemes. We find that many small feedstock molecules absorb most at short (∼200 nm) wavelengths, with decreasing UV absorption at longer wavelengths. For comparison, we also measured the nucleobase adenine and found that adenine absorbs significantly more than the simpler molecules often invoked in prebiotic synthesis. Our results enable the calculation of UV photon penetration under varying chemical scenarios and allow further constraints on plausibility and self-consistency of such scenarios. While the precise path that prebiotic chemistry took remains elusive, improved understanding of the UV environment in prebiotically plausible waters can help constrain both the chemistry and the environmental conditions that may allow such chemistry to occur.

The bubble theory: exploring the transition from first replicators to cells and viruses in a landscape-based scenario.

This study proposes a landscape-based scenario for the origin of viruses and cells, focusing on the adaptability of preexisting replicons from the RNP (ribonucleoprotein) world. The scenario postulates that life emerged in a subterranean "warm little pond" where organic matter accumulated, resulting in a prebiotic soup rich in nucleotides, amino acids, and lipids, which served as nutrients for the first self-replicating entities. Over time, the RNA world, followed by the RNP world, came into existence. Replicators/replicons, along with the nutritious soup from the pond, were washed out into the river and diluted. Lipid bubbles, enclosing organic matter, provided the last suitable environment for replicons to replicate. Two survival strategies emerged under these conditions: cell-like structures that obtained nutrients by merging with new bubbles, and virus-like entities that developed various techniques to transmit themselves to fresh bubbles. The presented hypothesis provides the possibility for the common origin of cells and viruses on rocky worlds hosting liquid water, like Earth.