Biogeny (Formation of Primitive Life)

What is Biogeny (Formation of Primitive Life)?

• Biogeny​‍​‌‍​‍‌​‍​‌‍​‍‌ is the term given to the phase in origin-of-life research when the non-living organic molecules were arranged in the first living things.
• It was considered the next stage after Chemogeny, which supported the chain of events through prebiotic chemistry by supplying monomers (amino acids, sugars, nucleotide precursors).
• The transition from non-living to living was usually interpreted by the Oparin–Haldane model, and this concept was brought back to life with current experiments.
• The formation of the first life was suggested to be led by informational polymers (mainly RNA), and the genetic + catalytic roles explained by the RNA World hypothesis were in line with this.
• Fox reported simple peptides (proteinoids) to be synthesized upon heating, and those were considered as primitive catalysts.
• As far as the issue of compartmentalization was concerned, coacervates (liquid droplets obtained by phase-separation) were identified as the possible precursor of the protocell.
• Coacervates were thought to concentrate RNA/proteins and cofactors (Mg²⁺ etc.) thus facilitating catalysis and replication, and this solved the chicken-egg paradox.
• Membrane-like boundaries were assembled later around such droplets (fatty acids/phospholipids assembling), thus hybrid protocells, which were more stable, being formed.
• This led to a cell-like entity of the earliest kind integrating information, catalysis, and compartment called an Eobiont (pre-cell), which could perform the most basic metabolism and growth.
• Their energy was described to be derived only from the ‘organic soup’ which allowed them to be chemoheterotrophic, and at first, the eobionts were portrayed as anaerobic, prokaryotic, and chemoheterotrophic; from there a few could have transitioned chemoautotrophic then photoautotrophic.
• The biogeny event needed replicators, a constant energy supply, and some isolation from the environment, and these conditions were assumed to be met by the early Earth environment.
• Put simply, Biogeny is the moment when chemistry was made to behave like life — chemistry → organized, self-sustaining biology, the turning point where evolution could come into play, however, the details are still researched and ​‍​‌‍​‍‌​‍​‌‍​‍‌debated.

1. Formation of nucleic acids and nucleoproteins

The formation of nucleic acids and nucleoproteins considered as one of the key transition in Biogeny where information molecules begin to store and transmit life instructions.

It started after Chemogeny produced small organic monomers like nucleobases, sugars, phosphates, etc.

Prebiotic synthesis of these monomers was supported by experiments—like the Miller–Urey experiment, which shown how simple gases (CH₄, NH₃, H₂, H₂O) could give amino acids and precursors.

Later, Joan Oró (1961) produced adenine from hydrogen cyanide (HCN) and ammonia, proving nucleobases could form abiotically.

Formamide chemistry also suggested as plausible route, as heating formamide with minerals produced nucleic bases and acyclonucleosides.

Some evidences from Murchison meteorite indicated that nucleobases and sugars may also come from space — this idea referred as pseudo-panspermia.

After monomers existed, condensation or polymerization occurred forming longer chains (nucleotides → RNA/DNA), though in water it was thermodynamically unfavorable.

Drying cycles or mineral surfaces (like clay, silica) were thought to aid this polymerization by concentrating reactants and removing water.

RNA World Hypothesis proposed that RNA appeared before DNA/proteins, acting both as genetic carrier and catalyst (ribozyme activity).

Thus RNA probably functioned as first replicator, later DNA evolved from it when systems became membrane enclosed.

Proteins (or proto-peptides) formed from amino acids under heat — as demonstrated by Sydney Fox, producing proteinoids with catalytic behavior.

The interaction of RNA and these peptides resulted in nucleoproteins—complexes where genetic material was coupled with functional molecules.

These complexes increased molecular stability, allowing information and catalysis to coexist, an essential leap towards living organization.

Inside primitive water bodies, such assemblies sometimes concentrated into coacervates, forming droplets rich in nucleic acids and peptides, giving small compartments for reactions.

Within coacervates, ribozymes remained active and replication reactions were enhanced since ions like Mg²⁺ were trapped at optimal levels.

Formation of such nucleoprotein–coacervate systems viewed as the immediate precursor to protocells, having both replication capacity and primitive metabolism.

Eventually these coacervates stabilized by lipid layers (fatty acids/phospholipids), forming the first boundary-enclosed life units — small pre-cells that later evolved into Eobionts.

Hence, the synthesis and association of nucleic acids with peptides provided the earliest molecular architecture of life, bridging chemical evolution to biological function.

2. Formation of Coacervates

The term Coacervate was first coined when scientists Bungenberg-de Jong and Kruyt described the process of coacervation, meaning separation of mixed colloids into two liquid phases.

Later, A.I. Oparin (1930s) proposed that primitive cell-like structures on early Earth were formed by this same mechanism.

He suggested that organic molecules (proteins, polysaccharides, nucleic acids etc.) in the primordial soup spontaneously separated into dense droplets — known as coacervates.

These droplets were rich in solute species and surrounded by a dilute outer medium, making them phase-separated compartments.

The mechanism occurred by associative interactions between oppositely charged macromolecules, leading to condensation of a dense inner phase.

Example – positively charged polylysine (pLys) and negatively charged RNA can form complex coacervates under mild conditions.

Other models shown coacervates could form also by mixing short peptides with nucleotides (ATP/ADP/AMP), or using polyamines like spermine with oligonucleotides.

These are considered prebiotically plausible since small peptides and nucleotides likely existed on early Earth.

The interior of coacervates was highly crowded, concentrating important molecules like RNA, peptides, and cofactors such as Mg²⁺, which improved catalytic efficiency.

Such concentration made possible faster reaction rates and molecular binding, providing a stable reaction space.

Coacervates contained water both inside and outside (unlike emulsions), allowing free diffusion and maintaining biochemical conditions similar to living cytoplasm.

Physical stability of coacervates was improved when small molecules like polylysine/ATP were used; they remained stable from pH 4–10 and even at 90°C.

Early critics called them molecular garbage bags, as they lacked selectivity and identity, but newer studies show controlled uptake of RNA and cofactors inside them.

Modern research demonstrated that ribozyme activity remains functional inside coacervates, supporting that such droplets could assist RNA replication.

A further improvement was the assembly of fatty acid or phospholipid membranes around coacervates—forming hybrid protocells, more resistant to merging and leakage.

These lipid-covered coacervates bridged the step between simple droplets and the first Eobionts (pre-cells), capable of primitive metabolism and division.

In this view, coacervates acted as natural microreactors, concentrating life’s ingredients and preparing ground for first living cell systems.

Therefore, the formation of coacervates marked one of the most drastic transitions in Biogeny, connecting the chemical soup to structured protocells.

3. Formation of Primary organism

The formation of primary organism known as the final phase of Biogeny, where complex chemical systems turned into the first living body (often called Eobiont or Pre-cell).

This step followed Chemogeny and coacervate formation, marking the boundary between non-living and living world.

For this conversion, three things were essential — continuous supply of replicating molecules, energy source, and some kind of isolation from outside environment.

Inside coacervate droplets, nucleic acids and enzymatic peptides became concentrated, creating the internal “cytoplasm-like” region.

A thin membrane developed around that cytoplasm, possibly by self-assembly of fatty acids or phospholipids, forming the earliest cell membrane.

These fatty layers (oleic acid, phospholipid vesicles, etc.) could assemble spontaneously by electrostatic attraction at the coacervate surface.

Studies suggested that simple molecules, like cysteine and choline thioester, could react on silica surface to produce lipids, showing prebiotic plausibility of such membranes.

With this boundary, protocells gained stability, preventing merging (coalescence) and protecting internal contents from dilution.

Once the boundary stabilized, internal metabolism begin to appear, supported by enzymatic reactions powered by molecules like ATP.

Modern simulation showed a “fueled” coacervate system using pyruvate kinase and hexokinase enzymes, where ATP formation and breakdown drove droplet growth and dissolution.

This type of dissipative chemical network helped protocells stay active—consuming fuel to remain far from equilibrium, just like modern life.

Growth occurred as internal material accumulated; eventually droplets divided, sometimes by budding or fragmentation, forming new units.

A theoretical model by Zwicker et al. proposed spontaneous division by shape instability when metabolic reaction exceeded threshold growth.

Experimental work by te Brinke et al. used bacterial protein FtsZ with GTP, where FtsZ filaments actively split droplets—an early mimic of biological division.

Thus, the first organism integrated three systems: information (RNA), catalysis (proteins/ribozymes), and compartment (membrane-bound coacervate).

That organism, called Eobiont, considered the earliest living structure capable of growth, replication, and energy use.

It was anaerobic because early Earth lacked free O₂, chemoheterotrophic as it used organic molecules from the soup for food, and prokaryotic—without true nucleus.

Over time, depletion of organic food led some to evolve into chemoautotrophs, then photoautotrophs, and later oxygen-producing forms like cyanobacteria.

The rise of the Eobiont therefore completed Biogeny — the moment chemistry first learned to self-renew, setting the ground for evolution to begin.