Abiogenesis is possible under current environmental conditions on Earth.
the verdict
INSUFFICIENT LEANING
refutedsupported
the weight of evidence
2 sources for · 0 against
Scientific sources indicate that abiogenesis occurred or requires conditions strikingly different from those found on Earth today, implying it is not currently supported by modern environmental conditions.
He proved that complex life forms, like flies or bacteria, do not just pop into existence from nothing.[2] But modern abiogenesis is different from that old idea. It does not say that complex life just appears. Instead, it suggests that life slowly formed over time through natural chemical reactions on the early Earth. These reactions may have turned simple non-living molecules into the first building blocks of life. One important experiment in 1952 helped support this idea. Two scientists, Miller and Urey, created an experiment, the Miller–Urey experiment, to copy what Earth’s atmosphere may have been like billions of years ago. They used water, methane, ammonia, and electricity (to act like lightning), and they were able to create amino acids, tiny molecules that make up proteins in living things. This showed that the basic parts of life could form naturally under the right conditions.[1][3]
Scientists today think that life on Earth began in a series of steps, not all at once. First, simple organic molecules, tiny building blocks like amino acids, formed from non-living materials.
Abiogenesis or the origin of life (sometimes called biopoiesis) is the natural process by which life arises from non-living matter, such as simple organic compounds. The prevailing scientific hypothesis is that the transition from non-living to living entities on Earth was not a single event, but a process of increasing complexity involving the formation of a habitable planet, the prebiotic synthesis of organic molecules, molecular self-replication, self-assembly, autocatalysis, and the emergence of cell membranes. The transition from non-life to life has not been observed experimentally, but many proposals have been made for different stages of the process.
The study of abiogenesis aims to determine how pre-life chemical reactions gave rise to life under conditions strikingly different from those on Earth today. It uses tools from biology and chemistry, attempting a synthesis of many sciences. Life functions through the chemistry of carbon and water, and builds on four chemical families: lipids for cell membranes, carbohydrates such as sugars, amino acids for protein metabolism, and the nucleic acids DNA and RNA for heredity. A theory of abiogenesis must explain the origins and interactions of these classes of molecules.
Many approaches investigate how self-replicating molecules came into existence. Researchers think that life descends from an RNA world, although other self-replicating and self-catalyzing molecules may have preceded RNA. Other approaches ("metabolism-first" hypotheses) focus on how catalysis on the early Earth might have provided the precursor molecules for self-replication. The 1952 Miller–Urey experiment demonstrated that amino acids can be synthesized from inorganic compounds under conditions like early Earth's. Subsequently, amino acids have been found in meteorites, comets, asteroids, and star-forming regions of space.
While the last universal common ancestor of all modern organisms (LUCA) existed millions of years after the origin of life, its study can guide research into early universal characteristics. A genomics approach has sought to characterize LUCA by identifying the genes shared by Archaea and Bacteria, major branches of life. It appears there are 60 proteins common to all life and 355 prokaryotic genes that trace to LUCA; their functions imply that LUCA was anaerobic with the Wood–Ljungdahl pathway, deriving energy by chemiosmosis, and used DNA, the genetic code, and ribosomes. Earlier cells might have had a leaky membrane and been powered by a naturally occurring proton gradient near a deep-sea white smoker hydrothermal vent; or, life may have originated inside the continental crust or in water at Earth's surface.
Although Earth is the only place known to harbor life, astrobiologists assume that life exists and came into being by similar processes on other planets. Geochemical and fossil evidence informs most studies. The Earth was formed at 4.54 Gya, and the earliest evidence of life on Earth dates from 3.8 Gya from Western Australia. Fossil micro-organisms may have lived in hydrothermal vent precipitates from Quebec, soon after ocean formation during the Hadean, so the process appears to have been relatively rapid in terms of geological time.
The largest unanswered question in evolution is how simple protocells first arose and differed in reproductive contribution to the following generation, thus initiating evolution. The lipid world theory postulates that the first self-replicating object was lipid-like. Phospholipids form lipid bilayers (as in cell membranes) in water while under agitation. These molecules were not present on early Earth, but other membrane-forming amphiphilic long-chain molecules were. These bodies may expand by insertion of additional lipids, and may spontaneously split into two offspring of similar size and composition. Lipid bodies may have provided sheltering envelopes for information storage, allowing the evolution of information-storing polymers like RNA. Only one or two types of vesicle-forming amphiphiles have been studied. There is an enormous number of possible arrangements of lipid bilayer membranes, and those with the best reproductive characteristics would have converged toward a hypercycle reaction, a positive feedback composed of two mutual catalysts represented by a membrane site and a specific compound trapped in the vesicle. Such site/compound pairs are transmissible to the daughter vesicles, leading to the emergence of distinct lineages of vesicles, subject to natural selection.
A protocell is a self-organized, self-ordered, spherical collection of lipids proposed as a stepping-stone to life, that is capable of evolving. Self-assembled vesicles are essential components of primitive cells. The theory of classical irreversible thermodynamics treats self-assembly under a generalized chemical potential within the framework of
The origin of life (OoL) is a fundamental and long-standing scientific question. Although a variety of plausible hypotheses had been put forward, how life began on the prebiotic Earth from a pile of prehistoric inert chemicals (gases) is still a puzzle to us. Here, to unify the existing hypotheses to cover the entire scenarios, the author proposed the "nanozymes hypothesis" of the OoL on Earth, in which natural mineral nanozymes (MN-zymes) and their later upgraded organic/inorganic hybridized nanozymes played multiple key roles in the initial emergence of life molecules, especially in the manner of "inorganic photosynthesis" under primitive Earth conditions. Under the hypothesis framework, proteins, DNA, and RNA might emerged near-simultaneously, as a result of the diversity of nanozymes and catalyses, and multiple physical and chemical key roles of the MN-zymes. Besides nanozyme aspects, several fundamental and key issues on the topic are briefly discussed and several essential elements and conditions for the natural selection and survival of life molecules are proposed.
It is well known that biological enzymes played important roles in the evolution of existing organisms and living organisms today, but strangely, the possible similar roles of their initial inorganic analogs, MN-zymes of the Earth, in the creation of living materials and the birth of life on early Earth were completely overlooked. In fact, naturally formed NPs of minerals are plentiful on Earth.
Annually, thousands of terragrams (Tg) (1 Tg = 10 12 g) of mineral NPs on Earth move around in natural ecosystems; some of them exhibit intrinsic enzyme-like characteristics (termed MN-zymes), which are ubiquitous in the oceans, waters, atmosphere, and soils, and play critical roles in environmental biogeochemical cycles [ 13 ].
Therefore, based on these and my long thinking on the fascinating topic and current explosion advances in artificial nanozymes, the author proposes herein the “nanozymes hypothesis” of the OoL (on
They gradually catalyzed the generation of prehistoric small life molecules from nonliving matter, a bunch of prehistoric inert chemicals (gases), via complex chemical (and physical) processes in the main way of “inorganic photosynthesis” under primitive Earth conditions.
With the advancement of science and renewal of knowledge, I, maybe we, believed that the primordial Earth environments itself actually had the basic conditions to initiate and support the emergence of life. In fact, the Earth itself has the ability to gradually cultivate organic life and world from a completely all-inorganic primordial Earth environment and harsh conditions in the long history of the birth and evolution of life on Earth (akin to previous abiogenesis opinion) [ 5 ]. Within the framework of the OoL hypothesis, the Earth is a natural “all-in-one” big and sustainable chemistry laboratory. As schematically depicted in Fig.
In addition, the natural sunlight conditions and lightning phenomena also provide sufficient photocatalytic and electrocatalytic reaction conditions for the upgraded mass production of primordial natural nanozymes and their later organic hybrid nanozymes, and the generation of rich prebiotic molecules on the Earth’s surface. Table 1 presents a preliminary summary of the literature survey [ 9 , 11 , 19 – 26 ], showing possible reaction activities and prebiotic molecules generable on Earth by some main MN-zymes (earth-abundant NMs) with (protoenzyme-like) catalytic activity, such as magnetite (Fe 3 O 4 ), FeS, and ZnS NPs.
Recently, more and more scholars have come to realize that natural AuNPs are an important component of gold under various geological conditions of the Earth, such as hydrothermal fluids, black chimneys on the seabed, hydrothermal gold deposits, and supergenic gold deposits; so far, natural AuNPs have been discovered in gold deposits such as Carlin-type gold deposits, orogenic gold deposits, skarn-type deposits, weathering crust gold deposits, and sedimentary rock-type gold deposits [ 38 , 39 ].
To better understand basic principles of the OoL from a physical and chemical perspective, the author proposed herein further 4 essential elements and conditions for the natural selection and survival of life molecules regarding the OoL on Earth, as shown in Box 2 , namely, wet–dry cycling and amphiphilism, self-assembly and self-organization, catalytic and protoenzyme activity, and pairing symbiosis and stabilization. Box 2.
Nature has its own set of rules and ways for the de novo synthesis of life (i.e., constructing a new form of life based on completely synthetic components) [ 57 ], and we should also keep in mind that under non-equilibrium conditions, the overall catalytic performance (of the nanozyme systems and vesicular systems) will be enhanced [ 58 ]. Also notably, CoA is vital to all life on Earth, as its functional subunit, pantetheine, is crucial in many origin-of-life scenarios.
Furthermore, besides the established prebiotic surface catalysis (FeS/Fe clays, montmorillonite, ZnS, etc.), we should not overlook the geochemistry of impact craters, especially the adenosine phosphorylation assisted by meteorites under proton irradiation conditions [ 66 ], which could solve the major hurdle of the abiotic phosphorylation of nucleosides in OoL studies, providing an alternative explanation for the “Phosphate problem” of OoL on Earth by using reduced phosphorus sources like pyrophosphite or amidophosphite.
However, each of these hypotheses can only explain relatively narrow parts of whole scenarios, no convincing “one-piece” hypothesis so far can unify them, to provide complete and credible scenarios of how original life can arise from a bunch of inert chemicals on the planet. In the nanozymes hypothesis, natural MN-zymes and their later upgraded organic/inorganic hybridized nanozymes played multiple key roles in the initial emergence of life molecules under primitive Earth conditions.
Everything we examined (2)
This check searched the claim as stated. It did not run a separate search for evidence against it.