Minimum Viable Organism

The interdependence of multiple variations and the role of chance events in the history of life make calculations a challenge for scientists. Let’s begin with life arising from non-living materials, or abiogenesis.

Abiogenesis

Abiogenesis refers to a theoretical process by which life could have arisen from non-living matter. Various hypotheses have been proposed to explain this process, including the Miller-Urey experiment, which demonstrated the formation of amino acids from simple inorganic precursors under conditions thought to simulate the early Earth's atmosphere.

Several factors contribute to the difficulty of calculating the probability of abiogenesis:

Complexity of Life's Building Blocks: Life as we know it is based on complex molecules such as nucleic acids (DNA and RNA), proteins, and lipids. The formation and organization of these molecules into functional systems capable of self-replication and metabolism is a highly complex process.

Vast Parameter Space: The number of possible chemical reactions, combinations of molecules, and environmental conditions that could have been involved in the origin of life is vast. The sheer number of possibilities makes it challenging to estimate the likelihood of any particular pathway leading to life.

Unknown Prebiotic Conditions: While scientists have made significant progress in understanding the conditions that may have been present on the early Earth, many aspects of the prebiotic environment remain unknown. This uncertainty makes it difficult to accurately model the conditions under which abiogenesis may have occurred.

Lack of a Single Comprehensive Theory: Multiple hypotheses have been proposed to explain the origin of life, including the RNA world hypothesis, the metabolism-first hypothesis, and others. Each hypothesis has its own set of assumptions and considerations, making it challenging to calculate an overall probability for abiogenesis.

Functional Proteins

Amino acids are the building blocks of proteins, which are essential for life.

Precise probabilities for the spontaneous formation of functional proteins from amino acids in the prebiotic environment is not straightforward, because the process depends on numerous factors that are still not fully understood.

The formation of proteins involves the assembly of amino acids into specific sequences based on genetic information. In living organisms, this process is facilitated by ribosomes.

The spontaneous formation of functional proteins from amino acids in the prebiotic environment would likely have been a rare event due to the vast number of possible amino acid sequences.

Energy Synthesis

The ability to harness energy is a fundamental requirement for life.

The Great Oxygenation Event (GOE) refers to a significant increase in atmospheric oxygen levels that occurred approximately 2.4 billion years ago. The GOE is thought to have been caused by the activity of these early photosynthetic organisms, which were capable of performing oxygenic photosynthesis. This process involves using light energy to split water molecules, releasing molecular oxygen (O2) as a byproduct.

We know that sunlight was available at the time, and to simplify the process we will make the assumption based upon a theoretical ancestor of modern Cyanobacteria that would have a minimum viable system capable of photosynthesis and subsequently produce molecular oxygen as a byproduct.

The table below explains the description and inclusive rationale for each component, as well as the single point of failure rationale, which explains why the absence or malfunction of each component would have detrimental effects on the organism's viability.

Minimum Viable Photosynthetic Organism Requirements

System	Description	Components	Single Point of Failure
Genetic Information System	DNA or RNA encoding the organism's genetic blueprint. Encodes instructions for building and maintaining the organism	DNA, RNA, Transcription machinery, MRNA, TRNA,	Without genetic material, the organism lacks information for replication and metabolism.
Protein Synthesis	Ribosomes and mechanisms for translating RNA to proteins	Produces functional proteins for various cellular functions	Without protein synthesis, critical cellular functions cannot be performed.
Photosynthetic Machinery	Pigments, photosystems, electron transport chain, ATP synthase	Enables capture of light energy, conversion to chemical energy, and oxygen release	Without photosynthetic machinery, the organism cannot generate energy or release oxygen.
Cell Membrane	Lipid bilayer or similar structure defining cell boundaries	Defines cell boundaries, regulates transport, maintains internal environment	Without a cell membrane, the organism lacks structural integrity and homeostasis.
Metabolism	Enzymes and biochemical pathways for energy generation and biosynthesis	Supports energy production, growth, repair, and synthesis of cellular components	Without metabolism, the organism cannot grow, repair, or maintain itself.
Energy Source	Availability of sunlight as an energy source for photosynthesis	Provides energy for cellular processes, metabolism, and maintenance	Without an energy source, the organism depletes energy reserves and cannot sustain life.
Reproduction	Mechanisms for cell division or replication (e.g., binary fission)	Allows for the propagation of genetic material and the continuation of life	Without reproduction, the organism cannot continue its lineage.
Regulation and Homeostasis	Mechanisms for regulating gene expression and maintaining internal balance	Ensures proper cellular functioning, response to environmental changes, and adaptation	Without regulation and homeostasis, the organism cannot adapt or maintain stability.
Catalysis	Enzymes and catalysts to accelerate biochemical reactions	Increases the rate of essential reactions, enables efficient metabolism	Without catalysis, essential reactions are too slow to sustain life.
Transport	Transport proteins and mechanisms for moving molecules across membranes	Facilitates intake of nutrients, removal of waste, and regulation of internal conditions	Without transport, the organism cannot acquire nutrients, excrete waste, or regulate ions.

Factors Involved For Calculating Probability of Success

Factor	Description	Formula
Solar Radiation	Availability of sunlight as an energy source	1:x1
Energy Conversion	Probability of energy conversion through efficient chemical reactions	1:x2
Light-Absorbing Pigments	Presence of pigments (e.g., chlorophyll) for capturing light energy	1:x3
Photosystem II (PSII)	Protein complex for splitting water, releasing oxygen, and initiating electron transfer	1:x4
Photosystem I (PSI)	Protein complex for capturing additional light energy and energizing electrons	1:x5
Electron Transport Chain	System for transferring electrons, generating proton gradient, and producing NADPH	1:x6
ATP Synthase	Enzyme for synthesizing ATP using proton gradient across membrane	1:x7
Energy Storage Molecules	Availability and formation of energy storage molecules (e.g., ATP)	1:x8
Catalysts	Presence of catalysts to facilitate energy synthesis reactions (e.g., enzymes, ribozymes)	1:x9
Membrane Transport	Probability of energy molecules and ions crossing membranes	1:x10
Redox Potential	Balance between reductive and oxidative conditions in environment	1:x11
Regulation	Probability of establishing regulatory mechanisms for energy synthesis and cellular homeostasis	1:x12
Amino Acid Pool	Availability of amino acids in prebiotic environment	1:x13
Protein Sequence/Folding	Chance of forming functional protein with correct sequence and 3D structure	1:x14 * 1:x15
Protein Chirality	Chance of having all L-amino acids in a functional protein	1:2^x14
Nucleotide Pool	Availability of nucleotides in prebiotic environment	1:x16
Nucleic Acid Sequence	Chance of forming functional nucleic acid with correct sequence and base pairing	1:x17 * 1:x18
Nucleic Acid Chirality	Chance of having all D-nucleotides for DNA or L-nucleotides for RNA	1:2^x17
Membrane Formation	Probability of forming lipid bilayers or similar structures	1:x19
Self-Replication	Probability that molecules assemble into system capable of self-replication	1:x20
Metabolism	Probability of establishing functional metabolic network	1:x21
Evolutionary Stability	Probability that system is stable enough to undergo evolution	1:x22
Functional Molecules	Probability of forming functional cofactors and small organic molecules	1:x23
Environmental Conditions	Suitability of environmental conditions (e.g., pH, temperature, minerals)	1:x24
Spatial Organization	Probability of achieving spatial organization and compartmentalization within cell	1:x25
Genetic Code	Probability of establishing a genetic code for translating genetic information	1:x26
Error Correction/Repair	Probability of having error correction and repair mechanisms for genetic material	1:x27
Interaction/Cooperation	Probability of interactions and cooperative behavior among molecules	ㅤ

Formula for Calculating Probability

To create a formula that comprises all of the estimated values, we can multiply them together. This formula represents the combined probability or estimate of all the factors listed in the table:

In this formula, each of the individual "Estimate" values from the table is multiplied together to get the total estimate or combined probability. Note that the terms "1:2^x9" and "1:2^x12" are included as specified in the original table.

Formula in LaTeX (copy for your use)


\text{Total\_Estimate} = (1:x_1) \cdot (1:x_2) \cdot (1:x_3) \cdot (1:x_4) \cdot (1:x_5) \cdot (1:x_6) \cdot (1:x_7) \cdot (1:x_8) \cdot (1:x_9) \cdot (1:2^{x_9}) \cdot (1:x_{10}) \cdot (1:x_{11}) \cdot (1:x_{12}) \cdot (1:2^{x_{12}}) \cdot (1:x_{13}) \cdot (1:x_{14}) \cdot (1:x_{15}) \cdot (1:x_{16}) \cdot (1:x_{17}) \cdot (1:x_{18})

In LaTeX, the underscore _is used to create subscripts for the variable names, and we use \cdotto indicate multiplication. The curly braces {} are used to group the subscripts when they have more than one digit (e.g., x_{10}). The 2^{x_9} notation is used to represent exponentiation.