Rodrigo Siqueira-Batista1,2*†
Ricardo Alves-Ferreira3*†
Rafaela Lacerda Pedra Maroca-de-Avelar4†Maria Isabel Cristina Batista Mayrink5†Eugênio Silva6,7†
Felipe Gómez8†- 1Department of Medicine, Faculdade Dinâmica do Vale do Piranga, Ponte Nova, Minas Gerais, Brazil
- 2Department of Medicine and Nursing, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
- 3Center of Bioethics and Applied Ethics, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- 4Department of Medicine, Faculdade Dinâmica do Vale do Piranga, Ponte Nova, Brazil
- 5Department of Pharmacy and Department of Nutrition, Faculdade Dinâmica do Vale do Piranga, Ponte Nova, Minas Gerais, Brazil
- 6Department of Exact Sciences and Engineering, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
- 7Department of Computer Science, Centro Universitário Serra dos Órgãos, Rio de Janeiro, Brazil
- 8Department of Planetary Geology and Habitability, Centro de Astrobiología, Madrid, Spain
Throughout the 20th and 21st centuries, studies into prebiotic chemistry have made a decisive contribution to research into the origins of life. This is the theme of this article, conceived as an integrative bibliographic review, carried out by consulting descriptors in DeCS (https://decs.bvsalud.org/) and MeSH (https://www.ncbi.nlm.nih.gov/mesh/), which enabled the design of the search strategies used to retrieve articles in PubMed (https://pubmed.ncbi.nlm.nih.gov/) and SciELo (https://scielo.org/). After the article selection process, 45 texts were chosen and used to prepare this manuscript. The information collected was organized into six sections – (i) Primordial chemistry of the Earth; (ii) First organic compounds; (iii) Prebiotic chemical structures; (iv) Original living beings; (v) Scientific perspectives; and (vi) (bio)ethical implications–in which the main results and respective discussions were gathered. It is important to highlight the long road that has been traveled towards a better understanding of the events that culminated in the origins of life. The link between science and ethics in this process is essential as a prerequisite for building responsible knowledge that considers the value of all forms of existence.
1 Introduction
The question of the origin of life on Earth has been the subject of significant studies, which drive the development of several explanatory models for what is considered one of the greatest enigmas of science (Tursi and Ribeiro, 2024). In fact, the understanding of the natural terrestrial environment and the living beings that inhabit it has demanded efforts to understand the emergence of current biological complexity (Lubenow et al., 2023).
Different views on the origin of terrestrial living beings have been produced throughout the history of thought, particularly from the 18th century (Zaia and Zaia, 2008). It is important to highlight the debate among the defenders of the spontaneous generation theory (abiogenesis) – such as John Turberville Needham (1713–1781) – and the proposers of the theory of biogenesis–p. ex., Francesco Redi (1626–1697) and Lazzaro Spallanzani (1729–1799) (Zaia and Zaia, 2008). After carrying out different experiments, in theory corroborating one and the other hypothesis, the question remained unsolved from a scientific point of view. Louis Pasteur (1822–1895), on the occasion of reactivated controversies with Félix Archimède Pouchet (1800–1872), provided greater support to the idea that life could only come from another form of life (Pasteur, 1922).
The question that arose from a scientific point of view, based on the supposed refutation of abiogenesis, could be formulated as follows: if living forms only arise from already existing living beings, how can we explain–scientifically–the emergence of life on Earth? This question can be answered with two main groups of explanatory proposals: (1) the (allochthonous) ex hypothesi, which considers that life was “imported” (e.g., brought by a meteor); and (2) the (autochthonous) in hypothesi, which formulates a local origin for terrestrial life forms. A third possibility would be the combination of both: alien, non-living molecules and components could have arrived on Earth and found favorable conditions to develop living beings.
Concerning the first set of ex hypothesi, it is noteworthy that the emergence of terrestrial life may be associated with explosions of stars, a phenomenon in which different chemical elements are formed. These elements, when combined, could give rise to different molecules essential for the formation of living organisms (Matsuura et al., 2011; Wuensche, 2019). In contrast, the Panspermia Theory proposes that life originated from meteors that arrived on Earth (Romeu, 2024). Aqueous alteration on meteorite provided the key mechanism for advancing organic chemistry. This environment enabled the mobilization and dissolution of prebiotic precursors (Kebukawa et al., 2020). As presented by The European Space Agency (ESA), this concept continues to be the subject of intense studies, since a comet has been investigated for bringing evidence of the amino acid glycine (C2H5NO2), an important precursor of proteins essential for survival (Altwegg et al., 2016).
Regarding the in hypothesi, the challenge of proposing a consistent explanation was independently faced by the Russian biochemist Aleksandr Ivanovich Oparin (1894–1980) and the English evolutionary biologist John Burdon Sanderson Haldane (1892–1964). The authors demonstrated that inorganic compounds such as methane (CH4), carbon monoxide (CO), carbon dioxide (CO2), hydrogen gas (H2), water (H2O), sulphidic acid (H2S) and ammonia (NH3) can react with each other to form biomolecules such as lipids, sugars, amino acids and nucleic acids. The union of these biomolecules is able to produce biopolymers such as peptides, polysaccharides and nucleotides, which in turn form structures called coacervates–microscopic structure formed by liquid microdroplets originated by spontaneous aggregation of biopolymers in the associative liquid-liquid phase separation (LLPS) (Lin et al., 2023) -, possible way for the emergence of life on primitive Earth (Moraes et al., 2024). Recent studies (Rodriguez LE. et al., 2024) detail the geological and chemical context of the Hadean (4.56–4.0 Ga), period in which the Earth passed from a hostile environment (ocean magma, intense bombardment) to stable conditions with anoxic oceans and atmosphere rich in CO2 and N2. In this scenario, processes such as serpentinization in alkaline hydrothermal sources generated gradients of pH and H2, fundamental for synthesis of organic molecules. In addition, mechanisms such as HCN polymerization, Fischer-Tropsch reactions and protometabolic cycles in microenvironments (such as coacervates) explain the transition from abiotic chemistry to biological systems. Geological evidence, such as 3.7 Ga stromatolites, reinforce the plausibility of these models. Decades later, Stanley L. Miller demonstrated that amino acids could be formed from gases such as hydrogen (H2), ammonia (NH3) and methane (CH4), by means of lightning-like electrical discharges propagating energy. This experiment reproduced the conditions of the prebiotic environment of the Earth and enabled the formation of compounds such as aspartic acid (C2 H5 NO2) and glycine (C H NO) (Zaia and Zaia, 2008; Luisi, 2016). These ideas are linked to the modern conception of the existence of original hydrothermal springs, high temperature and mineral-rich environments, which may have served as habitat for terrestrial primitive species (Georgieva et al., 2021).
Regardless of the theoretical model for the origin of life–ex or in –, chemistry acquires a central place in the proposition of hypotheses, an idea expressed, for example, in the conceptions of negentropy and metabolism (Schrodinger, 1994). In this context, prebiotic chemistry has great potential for the elaboration of consistent explanations for the origin of life. At first, the goal would be to understand how simple molecules such as methane (CH4), hydrogen (H2) and ammonia (NH3) could react and form biomolecules of sugars, lipids and amino acids (Zaia, 2004; JWST. James Webb Space Telescope, 2020). In this scenario, the energy required for molecular synthesis was supplied by diverse energetic processes, such as interactions with ionizing solar particles and the development of atmospheric photochemical networks–a complex, interconnected set of chemical reactions in the air, initiated and driven by sunlight. A web of interactions where the products of one reaction become the starting materials for others. These networks are responsible for creating and destroying various pollutants and natural compounds, shaping the chemical composition of our atmosphere. The most well-known example of an atmospheric photochemical network is the creation of ground-level ozone and smog in cities (McDonald et., 2025).
Based on these preliminary considerations, this article aims to review the main studies of prebiotic chemistry in relation to the origin of life and discuss the potential scientific developments and ethical issues of these investigations, with emphasis on the following points: (a) Earth’s primordial chemistry, (b) early organic compounds, (c) prebiotic chemical structures, (d) original living beings, (e) scientific perspectives and (f) (bio)ethical implications.
2 Methods
2.1 Keywords
The first step was the selection of uniterms–in DeCS (Health Science Descriptors: https://decs.bvsalud.org/) and in MeSH (https://www.ncbi.nlm.nih.gov/mesh/) – below related: (1) “Biochemistry”; (2) “Bioethics”; (3) “Biotic Factors”; (4) Chemistry; (5) “Ethics”; (6) “Extreme Environments”; (7) “Origin of Life”; and (8) “Planet Earth”. The descriptors were combined in search strategies, which were used for bibliographic research in PubMed (https://pubmed.ncbi.nlm.nih.gov/) and SciELo (https://scielo.org/) as presented in Table 1.
Table 1. Keywords used in the literature review and the number of articles found.
2.2 Study characteristics, selection of articles and exclusion/inclusion criteria
The exclusion criteria adopted were as follows: i) Articles that were not original research (e.g., dissertations, theses, abstracts, letters to the editor). Literature reviews were included only in exceptional cases, when they provided new insights on the topic under investigation; ii) Articles that did not address or relate to the central elements of this study, namely, the origin of life, prebiotic chemistry, or bioethics; iii) Articles that did not present current scientific perspectives on these subjects. Additionally, only articles published in Spanish, French, Italian, English, or Portuguese were considered. Figure 1 details the method used to perform the integrative literature review.
Figure 1. Method adopted for the integrative review in PubMed and SciELO. Source: The authors.
The application of the search strategy resulted in the recovery of 12,545 citations (PubMed = 12,503; SciELO = 42) (Table 1). Duplicates and articles that were not relevant to the purpose of this manuscript were removed after the titles and abstracts were read and found to be inadequate for the theme. Subsequently, the full texts were read, and articles with substantive information for addressing prebiotic chemistry and the origin of living beings were selected. At the end, 47 articles were selected and used for the organization of the results and discussion (Table 2), as discussed in the next section.
Table 2. Articles used in the composition of the integrative literature review.
3 Results and discussion
The information collected in the different articles selected to compose this study are summarized in Table 2.
The data obtained allowed, in a continuous act, the organization of the subjects relevant to the subject of the research into six topics – (1) Primordial chemistry of the Earth; (2) First organic compounds; (3) Prebiotic chemical structures; (4) Original living beings; (5) Scientific perspectives; and (6) (bio)ethical implications–which will be explained in detail below.
3.1 Primordial chemistry of the earth
The studies reviewed in this field share the fundamental idea that life, as it is known, may have originated from simple chemical reactions under specific conditions, favored by natural processes. This view is supported by a series of research that explores the different ways in which life-essential compounds may have formed, both on Earth and in other celestial bodies. For example, Miller’s work (Figure 2) pioneered experimentally demonstrating that organic compounds such as amino acids can form in a context that simulates the environment of the early Earth (Miller, 1953), reinforcing the hypothesis that life could have arisen from a prebiotic soup formed by simple molecules such as ammonia (NH3), methane (CH4) and hydrogen (H2). This concept–that organic compounds can arise spontaneously under suitable conditions–is reflected in Portilla (2011), which details the origin of the chemical elements essential to life through processes such as stellar nucleosynthesis and their subsequent dispersion in space, until they are incorporated into the formation of planets and eventually to Earth.
Figure 2. Miller-Urey Experiment. Source: The authors (Produced by Midjourney).
In 1953, Stanley Miller (University of Chicago) developed an experiment whose goal was to recreate the atmosphere of the Earth billions of years ago. In a closed glass apparatus (Figure 2), he mixed the gases they thought were common on the young planet–methane (CH4), ammonia (NH3), hydrogen (H2) and water vapor (H2O). These gases circulated through the system and continuously passed through electrical discharges that simulated lightning, generating free radicals. After 1 week of operation, the water in the system became red and cloudy, and analysis by paper chromatography identified the formation of amino acids such as glycine, α-alanine and β-alanine, in addition to other organic compounds. The process demonstrated that complex organic molecules, essential for life, can arise spontaneously in pre-biotic conditions with electrical energy. Sterilization (boiling water and HgCl2) eliminated biological contamination.
This pioneering result highlighted the importance of prebiotic chemistry for understanding the formation of life. This theme is articulated to the discussion conducted by authors such as Mariscal et al. (2019), who emphasize the philosophical and scientific issues that permeate the definition of life and the processes involved in its origin, arguing that over time, the transition from non-living matter to more complex forms of living can be better understood through a multidisciplinary approach, combining physical, chemical and biological sciences. In this sense, studies have proposed that the initial sources of hydrogen peroxide (H2O2) and molecular oxygen (O2) on early Earth could have been derived from mineral interactions, particularly at silicate–water interfaces (He et al., 2023), or could have originated from interactions between minerals and organic molecules, either through a biotic (Shang et al., 2022) or an abiotic (Shang, 2023) process (Figure 3). Similarly, Diederich et al. (2023) analyze how chemical processes such as the addition of emerging carbon (C2) units of acetylene (C2H2) and nickel sulfide (NiS) in hydrothermal conditions, may have promoted an important molecular diversity for the development of more complex systems, parallel to the formation of biological compounds. This concept of chemical evolution–which is reflected in the work of Rodríguez et al. (2024a) on the geochemistry of the primitive Earth –, also highlights the essential role of cycles of elements such as carbon, hydrogen, nitrogen, phosphorus, oxygen and sulfur in the formation of the fundamental blocks of life.
Figure 3. Fragments of possible mechanisms for H2O2 and O2 production at silicate mineral-water abrasive interfaces. Source: He et al. (2023).
Clark et al. (2021) research on Mars, for example, supports this view by suggesting that past Martian conditions could have been favorable for the formation of independent life, given the presence of liquid water and simple organic compounds. This is in line with the study by Huang (2024), which investigates the role of inorganic nanoparticles, such as iron oxide (FeO), in the first chemical reactions of the early Earth, suggesting that these particles could have acted as essential catalysts for the formation of complex molecules. This type of catalysis, also discussed by Edri et al. (2024), was fundamental for the advancement of chemical reactions that gradually led to life. In addition, Papineau et al. (2023) explore how Chemically Oscillating Reactions (COR) can mimic biological metabolic pathways, suggesting that self-similar patterns in abiotic reactions could have helped organize primordial chemistry in a way that favored the emergence of life.
The study of Ziurys (2024) on astrochemistry, especially aimed at the formation of complex organic compounds in space, reinforces this idea, showing that interstellar conditions can be a fertile ground for the origin of molecules essential to life, as amino acids and sugars, which could later be delivered to the Earth by meteorites, such as Murchison, in which the presence of amino acids had already been demonstrated in its composition. Similarly, the work of García-Sánchez et al. (2022) on molecular complexity in space, using a computational model to simulate interactive networks of chemical compounds, proposes that the formation of complex molecules in interstellar clouds can follow a path similar to that observed on early Earth, favoring the transition from chemistry to biology.
These investigations converge to an expanded understanding of the origins of life, suggesting that the chemical processes that occurred on early Earth–and possibly in other planetary environments–not only generated essential molecules, but also created the necessary conditions for the evolution of increasingly complex systems. Whether through simple chemical reactions in hydrothermal environments, by the formation of molecular networks in space or by the action of inorganic catalysts, the various researches present a panorama that not only reinforces the viability of the origin of life on Earth, from a scientific perspective, but also open up new possibilities for the search of living forms on other planets, demonstrating that events pertaining to prebiotic chemistry–from which living beings originated–can be a common phenomenon in the universe.
3.2 First organic compounds
The articles analyzed offer distinct but complementary perspectives on how life may have arisen from simple molecules, highlighting the importance of chemical interactions in the formation of complex organic compounds. The study by García-Sánchez et al. (2022), for example, presents a digital model that simulates the emergence of molecular complexity in environments such as interstellar space, suggesting that the chemical diversity observed in1 can be explained by the interactions between simple molecules under specific environmental conditions. This is directly connected with the idea of Vincent et al. (2021), who propose the concept of “prebiotic soups” – chemical mixtures created in the laboratory to simulate the conditions of the early Earth. Both studies indicate that, through simple interactions between molecules, more complex and essential forms for life could have been formed.
Another common point among the studies is the formation of key organic compounds such as sugars. The formose cycle (Figure 4), investigated by Kua and Tripoli (2024), is an important example, since it shows how some substances, such as formaldehyde, could generate sugars, fundamental for the formation of RNA, essential molecule for life. This study connects well with the research of Kankia (2023), which proposes the “quadruple world” hypothesis–a theory that suggests that guanine could have formed self-organized structures, functioning as a precursor to more complex biological systems. The idea is that these molecules could have given rise to the primordial genetic material, without relying on complex evolutionary processes.
Figure 4. Central autocatalytic cycle of the formose reaction. Source: Kua and Tripoli (2024).
Furthermore, other works highlight the crucial role of initial chemical reactions for the formation of biochemical systems. The study by Maguire et al. (2024), Figure 5, which explores the role of histidyl peptides in catalyzing reactions, is a good example of how some molecules may have facilitated fundamental metabolic processes.
Figure 5. The histidyl peptide-catalyzed prebiotic phosphate transfer system for the phosphorylation of organic building blocks of life (R–OH). Source: Maguire et al. (2024).
Similarly, Roche et al. (2023) investigate how the formation of proto-RNA nucleotides through supramolecular assemblies could have been a crucial step in the creation of primitive genetic systems. And the study by Krishnamurthy et al. (2022), in identifying nucleobases in meteorites, suggests that the fundamental blocks of life may have come to earth from space, offering another important piece in this puzzle. Together, these researches show us how, from certain interactions and specific chemical conditions, molecules and structures fundamental to life may have formed, beginning the biological complexity that is known today.
3.3 Prebiotic chemical structures
Studies on the origin of life and prebiotic chemical structures highlight a recurring theme among articles in this line: the central role of RNA in early life forms. Meyer et al. (2023) explore how RNA, besides being genetic material, would also have essential catalytic functions in the first biochemical reactions. They suggest that natural modifications in RNA molecules helped stabilize their structures, making them more functional in a prebiotic environment. They highlight how the concept of RNA stability aligns with the “RNA world” theory, advocated by Goldman and Kacar, 2021, who propose that many modern coenzymes are vestiges of an ancient world dominated by RNA, with essential catalytic functions at the beginning of life.
Another common point among the articles is the importance of prebiotic environments, where these molecules could form and evolve. Menor-Salván et al. (2022) investigate how nucleotides and pteridines (C6H4N4) could have emerged simultaneously, based on environmental conditions rich in urea (CH4 N2 O), a possible scenario of primitive life. The idea of chemical environments rich in essential life components is complemented by the work of Ding et al. (2024), which suggest that mineral protocells, surrounded by semipermeable membranes, could have solved challenges such as osmotic pressure. These membranes would have been vital to create a controlled environment, where the first chemical reactions could occur in a stable manner. The study by Cohen et al. (2024) on natural soda lakes also contributes to this view, suggesting that these environments could have provided ideal conditions for RNA polymerization and protocell formation. Already the study of Smith et al. (2021) discusses the similarities and differences between abiotic and biotic organic molecules (amino acids and sugars), highlighting the ambiguity in the distinction between them based on chirality and isotopic composition. Meteorites are presented as examples of abiotic end-members, while terrestrial biology represents biotic end-members. In their work Zhu et al. (2024) hypothesize that the abiogenic synthesis of carbon-based molecules, particularly long chain fatty acids, was a crucial stage in the emergence of life. Report the successful synthesis of long-chain carboxylic acids (C3-C7) with a remarkable yield of 42 mmol/g Co + Ni and a selectivity of 87.7% from the format, which is an intermediate in the acetyl-CoA route, indicating that the synergistic effect of the bimetallic catalyst increases C-C coupling, a vital process to generate longer carbon chains.
Moreover, the research of Huson et al. (2024) on self-generating autocatalytic networks brings an innovative approach to how chemical reactions could have evolved in a self-sustaining way in the early stages of life. The presented model of autocatalysis is also echoed in the work of Tekin et al. (2022), who explore the formation of lipid-stabilized foams, which could create moisture and drying cycles that favored the concentration and polymerization of molecules such as RNA. These conditions would help to form the first structures that gave rise to life. The research of Yin et al. (2019) on the transition from the world of RNA to protocells also complements this idea, showing that the emergence of protocells, or membranous compartments, was a crucial step for the evolution of more complex life forms, with the interaction between RNA, nucleotides and membranes becoming increasingly fundamental.
Finally, the work of Nitash et al. (2017) on digital evolution and self-replication of computer programs simulates the dynamics that may have occurred in early life forms. They investigate whether the first self-replicating was a single event or part of an ongoing evolutionary process, providing valuable insights into how life could have originated from self-generating systems, which suggests that the evolution of primitive life was a contingent and unpredictable process.
Together, the studies of these authors converge to the idea that the origin of life was not a single event, but rather a series of interconnected processes. The combination of RNA as a catalytic and informational molecule, the formation of protocells and autocatalysis in specific environments such as soda lakes or lipid foams all played crucial roles in the transition from non-living matter to complex biological systems. These studies not only explore different aspects of abiogenesis, but also help us understand that life as we know it today has deep roots in chemical and environmental processes that interacted to create the first living forms.
3.4 The original living beings
The articles selected in this area share a central theme related to the origin of life, whether in terms of its evolution on Earth, the search for life on other planets, or the definitions and characteristics that can help identify life in different contexts. McKay’s study (2011) focuses on the search for extraterrestrial life in the solar system–highlighting places like Enceladus, Europe, Mars and Titan–where conditions could allow life forms that may not be exactly as currently known. The author suggests that the detection of biomarkers and organic molecules could reveal that alien life, if it exists, would have different origins and biochemical than those found on Earth. In this sense, the article of Fernau, Braun and Dabrock (2020) deepens the discussion by exploring the concept of “life” within synthetic biology, where it seeks to create artificial forms of life. This is directly related to the McKay question, as the definition of life can be more flexible than one imagines, enabling new forms of existence in extraterrestrial environments.
On the other hand, the studies on the Last Universal Common Ancestor (LUCA) by Moody et al. (2024) and Delaye (2024) offer a fascinating insight into the first organisms that gave rise to life on Earth, highlighting that although the first beings are considered simple, its biological complexity was present in a rudimentary form. This opens a window to understand how life could have originated on other planets, possibly under similar conditions. The research of Wasik et al. (2019), with the hypothesis of the RNA world, also fits into this scenario, suggesting that the first life forms could have been based on RNA, molecules capable of replicating and evolving themselves, before the development of DNA and proteins. This theory broadens the possibilities of life in the universe, offering a basis for thinking about forms of life that could exist beyond the earth, in a completely different way from what we know.
These studies converge to a shared understanding that life–whether terrestrial, synthetic or alien–can arise from specific conditions that favor self-generating molecules and interconnected biological systems. Dick’s work (2012) also adds a philosophical and epistemological layer to this discussion, addressing the social and ethical implications of the search for extraterrestrial life. He highlights how astrobiology and scientific discoveries about life and its evolutionary foundations can change the human view of the universe. Together - as the work of Richards et al. (2024) advocates a cooperative and community-oriented approach to infer the set of genes from LECA (last eukaryotic common ancestor) providing recommendations for patterns in data sharing, methods of analysis and the need for transparency in the reconstruction process–these articles show that the origin of life, whether on Earth or beyond, involves a combination of scientific and philosophical factors. In addition, there is a growing recognition that life can be much more diverse than one imagines, and that its study requires interdisciplinary collaboration to expand the understanding of what it means to be alive.
3.5 Scientific perspectives
The advancement of scientific knowledge around the problem of the origins of life has opened a series of research frontiers, whose investigation could greatly expand the current understanding of the issue. Indeed, four main lines of study can be proposed: (1) the search for Earth analogues, studied in relation to chemical composition and possibilities for the origin of life; (2) metabolic studies with extremophiles, providing new insights into prebiotic chemistry; (3) the applicability of synthetic biology to research on the prebiotic chemical transition to life; and (4) the importance of computational techniques for clarifying the origins of life, which will be briefly discussed below.
3.5.1 The search for Earth analogues and the possibilities of the origin of life
The investigation of planets similar to Earth–using different technologies –, represents one of the most promising frontiers of astrobiology at the moment (JWST. James Webb Space Telescope, 2020). Historically, the search for other potentially habitable worlds began with the identification of exoplanets in the 1990s, when the radial velocity technique allowed the identification of giant celestial bodies orbiting nearby stars. Since then, methods such as planetary transit and astrometry have evolved, allowing the detection of rocky planets in habitable zones (Trifonov, 2024). The Kepler mission, launched in 2009, revolutionized the area by discovering thousands of exoplanets, including candidates for Earth analogues (Bienias and Szabó, 2025).
The identification of planets located in the habitable zone of their stars–with the possible presence of liquid water–increased the possibilities to find worlds with favorable conditions for the development of life (Mamajek and Stapelfeldt, 2023). These studies not only focus on the identification of exoplanets similar to Earth, but also investigate their atmospheres for chemical biosignatures–components that may indicate biological activity –, such as oxygen, methane and water vapor.
In this field, more recently, the James Webb telescope has brought an unprecedented breakthrough, given its ability to analyze exoplanet atmospheres through transmission spectroscopy. By observing starlight as it passes through the atmospheres of transiting planets, James Webb has the potential to identify these bio-signatures (Phillips et al., 2021). Studies using this telescope have the potential to detect water in exoplanets, which may suggest the possibility of habitable environments (Maltagliati, 2022). It is worth noting, however, that the interpretation of biosignatures still faces significant challenges. For example, compounds like methane and oxygen can be produced by abiotic processes such as volcanic activity or photochemical reactions. Indeed, it is essential to combine disparate lines of evidence to distinguish biological signals from natural geological processes. Such a multidisciplinary approach requires collaboration between astronomers, geochemists and astrobiologists to conduct investigations–beyond the direct and indirect observations of possible terrestrial analogues–using different scientific methods. Thus, climate and geochemical models have been used to simulate planetary conditions, allowing a better understanding of the variables that influence habitability (Charnay and Drossart, 2023; Vilovic et al., 2024). These simulations enhance the uses of biosignatures, increasing their predictability–and identification–in exoplanet atmospheres, which may contribute to the design of future space missions in the search for alien life.
3.5.2 Metabolic studies with extremophiles and prebiotic chemistry
Studies directed at extremophiles - organisms capable of living in extreme environmental conditions - have provided important insights into prebiotic chemistry and the origin of life (Amils and Gómez, 2021). By exploring how these life forms survive in high or low temperature environments, significant pH variations, boundary conditions of salinity/or high radiation exposure, open perspectives for the understanding of the limits of life and the possible conditions under which living organisms could have emerged on the primitive Earth or in other worlds (Aguzzi et al., 2024; Muscari Tomajoli et al., 2025; Rodriguez L. E. et al., 2024).
The research with extremophiles began to gain prominence in the 1960s, with the discovery by Thomas Brock of bacteria–more specifically, Thermus aquaticus–living in hydrothermal springs (Brock and Freeze, 1969). Since then, several extreme ecosystems have been identified, which has allowed the study of resident organisms, focusing on their metabolism, with a view to using alternative energy sources–p. e., chemosynthesis, rather than photosynthesis –, which can shed light on the chemical reactions that could have occurred in original living beings in a prebiotic environment (Palacios-Pérez and José, 2019; Rodriguez L. E. et al., 2024). In general, the biochemical apparatus of extremophiles consists of extremozymes, which are highly stable under hostile conditions and offer clues as to how the first biological reactions could have occurred in primitive contexts of life emergence (Gallo and Aulitto, 2024). For example, thermophilic bacteria, which thrive at temperatures above 100 °C, employ heat-resistant proteins that may have been instrumental in prebiotic chemistry in volcanic seas or hydrothermal springs.
Another important research front with the use of extremophiles concerns the testing of hypotheses about life in other celestial bodies. In fact, experiments simulating the environmental conditions of Mars or the icy moons of Jupiter and Saturn–Europa and Enceladus–revealed that certain extremophiles could survive in extraterrestrial environments (Dos Santos et al., 2024). Indeed, life forms capable of developing in extreme contexts challenge the traditional definitions of habitability, suggesting that life can exist in conditions far beyond those considered ideal for terrestrial organisms, considering only the chemistry of carbon (that is, without taking into account other possible molecular arrangements for life) (Siqueira-Batista and Gómez, 2025). Such a scenario expands the search for extraterrestrial life, encouraging the exploration of environments previously considered inhospitable.
3.5.3 The applicability of synthetic biology to research on the prebiotic chemical transition to life
Synthetic biology – “a field of biological research combining engineering in the formulation, design, and building (synthesis) of novel biological structures, functions, and systems” (MeSH, 2025) – emerged as a frontier discipline for astrobiology, by providing important tools to investigate the transition of prebiotic chemistry to early living systems. The construction of artificial biological systems allows the study on the organization of simple molecules in complex structures with biological functions, elucidating potential paths for the emergence of life (Malaterre et al., 2022; Solé et al., 2024). This is a scientific approach that allows the construction of artificial protocells that behave like living systems–providing ideas about the ways in which chemical components could have organized themselves into functional structures–from which it is possible to formulate and test hypotheses on (i) the formation of original membranes, (ii) the first metabolisms and (iii) the development of molecular replication systems (Luisi, 2016).
The formation of protocellular membranes–composed by fatty acids and simple lipids–is essential for understanding how cell beginnings compartmentalized chemical reactions, which allowed the development of typical properties of biological systems, such as growth, maturation and division (Piedrafita et al., 2017; Pohorille et al., 2003). Such investigations are significant to allow the understanding of how the first biological compartments could have been organized, spontaneously, in prebiotic environments.
The construction of synthetic metabolisms is another emerging field, in which metabolic pathways are designed for the conversion of simple compounds into complex organic molecules (Abil et al., 2025; Haas and Nikel, 2023). This perspective supports the theoretical formulation that life could have started in chemosynthetic environments, such as hydrothermal sources, where energy gradients and concentration could have driven original metabolic reactions.
One of the promising approaches in synthetic biology is the construction of RNA and DNA replication systems. By synthesizing ribozymes and artificial polymerases, it is possible to study how the first molecules with “genetic” characteristics could have evolved, an event considered crucial for the emergence of mechanisms of heredity (Chaput et al., 2012; Peng et al., 2021). It is noteworthy that some of these investigations may offer, for example, support to the previously mentioned hypothesis of the “RNA World”.
3.5.4 The importance of computational techniques for clarifying the origins of life
Computational techniques have played an important role in research on the origins of life, allowing the analysis of significant volume of experimental data and the modeling of complex processes pertaining to the origins of life. These approaches assist in identifying patterns and producing correlations between chemical and prebiological data, accelerating the formulation and testing of hypotheses–about (i) the emergence of life on Earth and (ii) the possibility of identification of extraterrestrial life forms (Abramov et al., 2021; Shapshak, 2018; Witze, 2023) – which may allow the exploration of scenarios that would be difficult to test experimentally, with emphasis on primitive metabolic networks and the formation of biological polymers.
The potential use of data mining and machine learning techniques to analyze chemical databases–from the available knowledge about prebiotic Earth–represents an interesting frontier for research. The application of machine learning algorithms for the extraction of knowledge not immediately explicit may reveal the existence of emerging patterns, which would lead to eventual plausible chemical routes for the synthesis of essential biomolecules, as amino acids and nucleotides under conditions prior to the emergence of life (Clough et al., 2025).
Artificial intelligence techniques, in a general way, may be useful for modeling dynamic systems and predicting the evolution of primitive metabolic networks–which includes the simulation of molecular interactions and the study of protocell stability–investigations that can assist in understanding about how simple chemical systems could have evolved into self-replicating and adaptive entities (Wani and Banday, 2024).
Computational tools also have applicability in astrobiology, allowing the analysis of spectroscopic data from exoplanet atmospheres for the identification of potential biosignatures (Corenblit et al., 2023; Figueroa et al., 2024). Optimization techniques based on evolutionary computation, such as genetic algorithms, have been used to optimize habitability scores in exoplanets. Habitability scores, such as the Cobb-Douglas score, are a kind of metric to evaluate habitability, thus allowing the systematic evaluation of several exoplanets (Krishna and Pentapati, 2019). Such scientific endeavors are ideal for the search for extraterrestrial life, allowing the detection of subtle patterns in planetary spectra–from the use of AI algorithms –, which could indicate the presence of complex organic compounds and, in the best possible scenario, point out the possible existence of life forms.
3.6 (Bio)ethical implications
The bioethical implications associated with the origins of life and prebiotic chemistry, as described in the text, encompass philosophical, scientific and social issues that challenge understanding about what life is, its uniqueness and its place in the cosmos. The interdisciplinarity inherent in these studies–which combine chemistry, physics, biology, astrobiology and philosophy–reveals profound ethical dilemmas, especially when considering the possibility of extraterrestrial life, the creation of synthetic life and the manipulation of prebiotic processes in the laboratory. The difficulty in defining life unequivocally, as discussed by Mariscal et al. (2019), generates ethical uncertainties. If life is understood as a chemical continuum (Smith et al., 2021), how to categorize intermediate systems such as protocells or self-catalytic networks (Huson et al., 2024)? This ambiguity affects not only scientific research, but also biosafety policies and the regulation of experiments in synthetic biology. In fact, Fernau, Braun and Dabrock (2020) warn that the creation of synthetic organisms challenges ethical boundaries, since artificial systems can exhibit borderline properties between the living and the non-living, requiring a review of moral criteria for granting rights or protections.
The application of synthetic biology to recreate prebiotic processes, such as the formation of protocellular membranes (Piedrafita et al., 2017) or primitive metabolisms (Haas and Nikel, 2023), places the scientific community before the dilemma of “playing God”. The synthetic artificial life, although rudimentary, implies risks of accidental release or misuse (Malaterre et al., 2022). In addition, as pointed out by Dick (2012), the manipulation of self-replicating systems (e.g.,: synthetic RNA, Meyer et al., 2023) requires strict protocols to avoid unforeseeable consequences on natural ecosystems, reinforcing the need for global governance in high-impact research. The search for biosignatures in exoplanets (Phillips et al., 2021) and the exploration of environments such as Mars (Clark et al., 2021) raise questions about cross-contamination. McKay (2011) argues that the accidental introduction of terrestrial microorganisms into other planets could destroy nascent alien ecosystems, violating the ethical principle of non-interference. NASA plays a critical role in planetary protection, balancing scientific exploration with the prevention of cross-contamination between celestial bodies. Based on studies such as The Limits of Organic Life in Planetary Systems (2007), the agency recognizes that terrestrial life, adaptable to extremes like hydrothermal springs (Kashefi and Lovley, 2003), could colonize environments like Mars or Europe, as extraterrestrial life forms with alternative biochemistries (e.g., non-DNA based polymers) require advanced detection instrumentation (Benner et al., 2004). NASA revises sterilization protocols and missions, incorporating research in synthetic biology and terrestrial analogue environments, to avoid false negatives and contamination. Its strategy, still centered on “following the water,” evolves to include non-aqueous solvents and universal biomarkers, reflecting an ethical and scientific commitment: exploring the unknown without compromising extraterrestrial ecosystems or the integrity of the alien life hunt. On the other hand, the detection of extraterrestrial life would require guidelines for public communication, avoiding panic or cultural appropriation, as discussed by Dick (2012). Astrobiological ethics therefore demands a balance between scientific curiosity, precaution and protection.
The hypothesis that life is a universal phenomenon (Ziurys, 2024) destabilizes the anthropocentric notion of human singularity. Mariscal et al. (2019) question whether terrestrial life is a cosmic accident or part of an inevitable evolutionary pattern, which influences our ethical responsibility towards other forms of life. The discovery of life based on alternative biochemists, as proposed by García-Sánchez et al. (2022), would require rethinking concepts of intrinsic value, extending the scope of environmental ethics beyond the terrestrial biosphere and to the cosmos–involving all beings–as proposed by Siqueira-Batista (2020). Research with extremophiles (Rodriguez et al., 2024a) not only illuminates the origins of life but also allows the exploitation of resources in hostile environments such as hydrothermal springs or Martian subsoils. This creates dilemmas about bioprospecting and exploration rights in extraterrestrial ecosystems. The applicability of (bio)ethics for all beings to astrobiology, as discussed by Siqueira-Batista and Gómez (2025), should consider the preservation of extreme habitats on Earth and in space as repositories of unique biodiversity.
Studies on the Last Universal Common Ancestor (LUCA), such as those of Moody et al. (2024), reveal that primitive life already exhibited biochemical complexity. This challenges reductionist narratives about the “simplicity” of early life, with implications for scientific education and public dialogue. The reconstruction of ancestral genomes, as proposed by Richards et al. (2024), also raises questions about the manipulation of archaic genetic sequences, which could be patented or used in controversial biotechnologies. The interaction between prebiotic chemistry, astrobiology and synthetic biology requires an adaptive ethical framework capable of integrating philosophical uncertainties and technological risks. Authors such as Dick (2012) and Mariscal et al. (2019) emphasize that bioethical reflection should be intrinsic to the scientific process, promoting interdisciplinary collaboration and dialogue with society. After all, understanding the cosmic origins of life is not just a search for ancestral molecules, but a journey to redefine the place of the human species in–and its responsibility towards–the universe.
4 Final thoughts
Prebiotic chemistry faces the central challenge of elucidating how life emerged from abiotic chemical processes on the early Earth. This challenge is organized into three main axes of debate, which constitute the core of this manuscript. In the current studies, it is highlighted the persistence of divergences between endogenous models (such as the synthesis of amino acids in experiments like Miller-Urey, reactions in hydrothermal sources and the formation of coacervates) and exogenous (panspermia, with evidence of organic molecules in meteorites such as Murchison). Recent research explores the catalysis by iron oxides minerals (FeO and Fe2O3), autocatalytic cycles (formose) and the role of primordial RNA, as well as computational simulations of interstellar environments and protocells. In scientific perspectives, the search for terrestrial analogues in exoplanets (through James Webb telescope), the use of synthetic biology to recreate primitive metabolisms and the exploration of extremophiles to understand biochemical limits can be highlighted, expanding the notion of cosmic habitability. Ethical questions involve dilemmas such as the contamination of extraterrestrial ecosystems during space missions, the risks of creating synthetic life in the laboratory and the philosophical implications of discovering alternative biochemistries, which will require the review of anthropocentric paradigms and guidelines for cosmic preservation. These fronts reflect the complexity of combining empirical evidence, technological innovation and ethical responsibility to unravel the origins of life.
The primordial chemistry of the Earth has been investigated using models that simulate prebiotic environments, such as hydrothermal sources and mineral-water interfaces. In these environments, reactions between simple compounds, including CH4, NH3, and H2, could generate essential biomolecules, such as amino acids and sugars, as demonstrated by classic experiments like those of Miller (1953). The first organic compounds, including nucleobases and polymers, probably emerged from autocatalytic cycles (e.g.,: formose), catalysis by nanoparticles (FeO, NiS) and exogenous contribution via meteorites (Murchison). It should be noted that computational models seem to suggest universal patterns of molecular complexification. Prebiotic chemical structures, such as coacervates and protocells with lipid or mineral membranes, demonstrate the compartmentalization of reactions, while RNA stands out as a key molecule (RNA World) for its catalytic and genetic functions. On the original living beings, the Last Universal Common Ancestor (LUCA) is associated with thermophilic environments and geochemical energy dependence, which allows the establishment of correlations with contemporary extremophiles. At the same time, the search for extraterrestrial life (e.g., on Mars and other celestial bodies) and synthetic biology broaden perspectives on alternative biochemistry of pre-biotic systems.
The scientific perspectives covered, as was sought to delimit, four important scientific frontiers: the search for Earth analogues, considering that the possibility of identifying habitable environments will depend on the integration of astronomical observations with theoretical models and laboratory experiments; the study of extremophiles, recognizing that as these organisms are better characterized–including those yet to be described –, their aspects may reveal crucial information about the chemical processes that led to the emergence of life on Earth; synthetic biology, which can offer a significant platform for the investigation of the pre-biotic chemical transition to life, which includes the possibility of creating artificial life forms in the laboratory; and computational techniques, which provide substantive tools for data analysis, the modeling of complex systems and the prediction of evolutionary scenarios, in order to articulate the pre-biotic chemistry and the emergence of life.
The studies on the origin of life confronts multidimensional bioethical challenges, from the ambiguous definition of “life” – which makes it difficult to categorize boundary organizations as protocells and autocatalytic networks (Huson et al., 2024) – to the risks of synthetic biology, where the creation of artificial organisms (Fernau et al., 2020) and the synthesis of protocellular membranes (Piedrafita et al., 2017) raise moral dilemmas about human intervention in these systems as well as expose impasses around biosafety. Space exploration requires strict protocols, such as those reviewed by NASA, to avoid cross-contamination in environments like Mars (McKay, 2011), while the hypothesis of universal life (Ziurys, 2024) demands a cosmic environmental ethic–perhaps (Bio)ethics for all beings (Siqueira-Batista and Gómez, 2025) –, able to preserve alternative biochemical (Benner et al., 2004) and extreme habitats beyond the Earth. Studies on LUCA (Moody et al., 2024) and the reconstruction of ancestral genomes (Richards et al., 2024) broaden debates about bioprospecting and patents, while interdisciplinarity (Mariscal et al., 2019) reinforces the need for an adaptive ethical framework, integrating precaution, innovation and social dialogue.
There is still much to be done in scientific terms for the elucidation–likely–of the origins of life. In this scenario, it is possible that substantive advances can be obtained in the coming years, perhaps from the research fronts listed in this article. One cannot forget, however, the necessary articulation between knowledge and ethics, in favor of the balance involving curiosity for the unknown and the responsibility to preserve the diversity of existence, terrestrial or cosmic, in a universe where life can be as singular as it is plural.
Author contributions
RS-B: Conceptualization, Data curation, Investigation, Project administration, Supervision, Validation, Visualization, Writing – original draft, Writing – review and editing. RA-F: Data curation, Formal Analysis, Investigation, Methodology, Writing – original draft, Writing – review and editing, Conceptualization, Supervision, Validation, Visualization. RM-d-A: Data curation, Formal Analysis, Investigation, Methodology, Visualization, Writing – review and editing. MM: Conceptualization, Data curation, Formal Analysis, Investigation, Supervision, Validation, Visualization, Writing – review and editing. ES: Conceptualization, Data curation, Methodology, Project administration, Supervision, Writing – review and editing, Validation, Visualization. FG: Data curation, Formal Analysis, Project administration, Supervision, Validation, Visualization, Writing – review and editing, Investigation.
Funding
The author(s) declared that financial support was received for this work and/or its publication. The authors are grateful to the Centro de Astrobiología (CAB/CSIC/INTA) for financial support for the article processing charge (APC).
Conflict of interest
The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Keywords: biochemistry, bioethics, biotic factors, chemistry, ethics, extreme environments, origin of life, planet earth
Citation: Siqueira-Batista R, Alves-Ferreira R, Maroca-de-Avelar RLP, Mayrink MICB, Silva E and Gómez F (2026) Prebiotic chemistry and origin of living beings: current state, scientific perspectives and (bio)ethical issues. Front. Astron. Space Sci. 12:1682489. doi: 10.3389/fspas.2025.1682489
Received: 09 August 2025; Accepted: 08 December 2025;
Published: 04 February 2026.
Edited by:
Alejandro Heredia-Barbero, Universidad Nacional Autónoma de México, MexicoReviewed by:
Jianxi Ying, Ningbo University, ChinaHaitao Shang, The University of Texas at El Paso, United States
Copyright © 2026 Siqueira-Batista, Alves-Ferreira, Maroca-de-Avelar, Mayrink, Silva and Gómez. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Rodrigo Siqueira-Batista, cnNiYXRpc3RhQHVmdi5icg==; Ricardo Alves-Ferreira, ZGllc2VsZmVycmVpcmFAZ21haWwuY29t
†ORCID: Rodrigo Siqueira-Batista, doi.org/0000-0002-3661-1570; Ricardo Alves-Ferreira, doi.org/0009-0007-1544-7701; Rafaela Lacerda Pedra Maroca-de-Avelar, doi.org/0009-0001-0013-9606; Maria Isabel Cristina Batista Mayrink, doi.org/0000-0002-7422-2066; Eugênio Silva, doi.org/0000-0002-9030-2242; Felipe Gómez, doi.org/0000-0001-9977-7060