Natural Philosophy of Protoplanetary and Planetary Discs: On the Origin and Evolution of Life

This paper examines the four pivotal and most contentious issues within the field of abiogenesis by analyzing the life-originating processes centred on protoplanetary and planetary discs. These include: 1. Geological environment; 2. Source of nutrients/initial molecules; 3. Source of energy; 4. RNA world versus metabolic world: which came first? To date, scientists have been unable to reach a consensus on these questions. Regarding geological environment, the distinct conditions within the inner, middle, snow line, and outer regions of the protoplanetary disc—including solar, cosmic, and isotopic radiation—along with the exchange of dust and gases between these zones, provided an exceptional reaction platform for prebiotic chemistry. Concerning the origin of life's food/precursor molecules, the protoplanetary disc—the stellar gas and dust disc formed during star formation—served as a crucial transitional stage linking interstellar matter to life's chemical potential. Transition metals, short- and long-lived radioactive isotopes, polycyclic aromatic hydrocarbons (PAHs), fullerenes, and the metal-organic compounds formed from these substances play a crucial role in life's composition. Analysis of meteorites reinforces the credibility of the protoplanetary and planetary discs as potential sites for the origin of life. Quantum mechanics may significantly influence the possibility of life emerging within protoplanetary discs. Regarding energy sources, the energy required for the emergence of life is quantifiable. The energy driving life's birth and evolution within protoplanetary and planetary discs can be summarized by the equations F = ma and ΔE = Δm × c². These energy sources derive not only from the kinetic energy of the protoplanetary disc and interactions between dust particles, expressed by F=ma, but this kinetic energy can also be converted into chemical reactions, ultimately yielding prebiotic effects. Energy generated by radiation from the decay of radioactive isotopes within the protoplanetary and planetary discs, alongside energy produced by solar nuclear fusion, can be expressed by the formula ΔE = Δm × c². This energy not only generates heat but, crucially, produces radiolysis effects through solar radiation, cosmic rays, and isotope decay. These effects facilitate prebiotic chemical reactions and provide sustenance and nutrients for life within the planetary disc. Concerning the RNA-world versus metabolism-first debate, the high concentrations of PAHs and fullerenes in protoplanetary discs and planetary discs, coupled with their influence on the formation of aromatic amino acids and aromatic hydrophobic proteins affecting nucleic acid molecular chirality, underscore the metabolism-first theory. The discovery of Hemolithin in meteorites and its implications for RNA generation reinforce the "metabolism precedes genetics" theoretical framework. Starting from Hemolithin and primitive metabolic systems found in meteorites, lipid membrane vesicles encapsulated metabolic small molecules and informational polymers. Sustained by external energy sources, these gradually evolved into primitive systems possessing the tripartite functions of "replication–metabolism–boundary". It subsequently led to the integration of energy, protein metabolism, and membrane–genetic systems within protoplanetary and planetary discs. Ultimately, a self-maintaining and self-replicating cycle system was established within the planetary disc. The core emphasis of this paper lies in the continuity and consistency, spanning hundreds of millions of years, of the gas and molecular dust composition within the protoplanetary disc and the gases and molecules that could be generated within planetary disc planetesimals. It provided a stable energy source and an excellent sanctuary for the birth of life within the protoplanetary disc and the evolution of life within planetary disc planetesimals. The philosophical coherence that life should emerge wherever gases and molecules exist elucidates the availability of protoplanetary disc gases and molecules (such as H2, CO, and electrons) alongside the bacteria consuming these substances within the disc's planetesimals. These gases and molecules are generated within planetary disc planetesimals by radioactive isotopes (such as 26AL,60F, 238U, ⁴⁰K), simultaneously producing oxygen radicals and hydrogen peroxide (e.g., H₂O₂, •OH, O₂•⁻, NO₃⁻). Thus, isotopes provided both the energy for bacterial survival and the nutrients required for bacterial metabolism, while simultaneously generating oxygen-free radicals and hydrogen peroxide that constituted a hazard to these bacteria. Consequently, bacteria acquired the capacity to resist oxygen-free radicals and hydrogen peroxide while obtaining the nutrients essential for their metabolism. The core of this process lies in the "radiation-metabolism coupling" and "radiation-metabolism co-evolution" hypotheses concerning the origin of life in protoplanetary and planetary disks. Within this theoretical framework, radiation-generated gases, molecules, and oxygen free radicals coexisted long-term with bacterial metabolism and antioxidant functions, forming the "radiation-metabolism co-evolution" model for life's origin. Only this "radiation environment-metabolism co-evolution" hypothesis can explain the survival characteristics exhibited by all bacteria and viruses we observe today. The fundamental reason why bacteria, archaea, and viruses possess exponentially higher radiation resistance than mammals lies in the direct consequence of these microorganisms' prolonged coexistence with radiation within planetary disks. Affected by the reducing atmosphere of the protoplanetary disk, the internal environment of planetesimals in the protoplanetary disk is mainly reduced, while the internal environment of planetesimals in the planetary disk is mainly oxidized due to the influence of short- and long-lived isotopes.Evidence from the significantly higher abundances of short-lived radioactive isotopes (SLRs) and long-lived radioactive isotopes (LLRs) in Murchison meteorite and other meteorites compared to the Earth's crust has highlighted the central theme of ‘radiation-metabolism co-evolution’. Research on the Great Oxygenation Event (GOE) demonstrates that this event, dominated by cyanobacteria, represents a consistent progression from ‘radiation-metabolism coupling’ and ‘radiation-metabolism co-evolution’ to radiation-metabolism-atmosphere environmental change. Comparing sulphur isotope mass-independent fractionation (S-MIF, Δ³³S) before and after the Great Oxygenation Event (GOE) with planetary disc material reveals that the GOE effectively restored Earth's S-MIF state to the oxidized conditions present in the planetary disc. It further demonstrates that bacteria originating from the planetary disc transformed Earth's atmosphere into the oxidized environment they inhabited within the disc – the very environment that sustains our existence today. Finally, it is discussed that the highly efficient aerobic metabolism of eukaryotes is also directly descended from the antioxidant bacteria present in protoplanetary disc planetesimals. Migratory birds, which traverse Earth's magnetic field lines, share connections with bacterial antioxidant mechanisms and primordial genetic material. Finally, constructing a novel Tree of Life reveals that the evolutionary lineage of life differs entirely from our currently accepted model. The roots and trunk of this evolutionary tree do not originate on Earth, but rather on the planetary disc. Two branches diverge from the trunk: bacteria and archaea. The archaea branch further gives rise to a branch of eukaryotes, constituting the primary life forms on our planet today. Meanwhile, bacteria, archaea, and viruses continue to evolve both on the planetary disc and on Earth, exerting influence upon the life forms evolving on our planet. Given that fullerene (C₆₀) itself exhibits quantum wave-particle duality, akin to the quantum effects observed in light, electrons, protons, and neutrons, the associated electro-nutritive bacteria—which convert electrons into nutrients—also possess quantum properties. It constitutes the pivotal link in this paper's integration of quantum mechanics into the origins of life. This analytical discussion further suggests that the essence of life and consciousness may fundamentally be quantum in nature. Under this premise that the essence of life and consciousness is quantum, the boundaries between physics, life, and consciousness may dissolve. At a deeper philosophical level, electro-nutritive life embodies the biological manifestation of quantum order. The electron resonance, coherence, and wave-particle duality exhibited by fullerene do not vanish with the emergence of life but gain structural continuity at the cellular level. It indicates that life's metabolism and consciousness are not entities 'transcending' the physical, but rather self-organized stages of the physical quantum order. From the cosmos to life, electron flow constitutes the sole truly continuous language of energy. As 'cosmic quantum energy nodes', fullerenes become, in a metaphysical sense, the mediating symbols between matter and life. Life's existence depends on the flow of energy. From stellar radiation to molecular chemistry, through neural activity to conscious experience, energy remains uninterrupted, merely organized and encoded at different levels. At the cosmos's inception, energy existed as quantum field oscillations. Within protoplanetary discs, it underwent physical transformation through electron flow via fullerenes, PAHs, and Fe–S systems; within living organisms, this electron flow becomes the carrier of information, driving neural activity and metabolic equilibrium. Thus, spanning from the physical to the biological, from molecules to consciousness, there exists a continuous "quantum electron flow continuum"—one that not only con