Rosa Rubicondior: Abiogenesis News - Closing Creationism's Favourite God-Shaped Gap

Diagram of an early cell membrane.

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How membranes may have brought about the chemistry of life on Earth | Department of Biology

Another hefty spadeful of science has just been shovelled into one of creationism’s favourite god-shaped gaps: the ever-shrinking mystery of abiogenesis. This is the gap that, through the intellectually dishonest tactic of the false dichotomy, creationists claim as evidence for their chosen deity.

Not only is this approach scientifically bankrupt, it also conveniently spares them the bother of providing any evidence or a testable mechanism of their own. For a target audience conditioned to see science as an attempt to disprove their god, the logic goes: if science is wrong—or even just incomplete—then “God did it!” wins by default.

But that dreaded moment for creationists, when science finally closes the gap and, like every other gap in history, finds no need for gods or magic in the explanation, draws ever nearer. The latest discovery bringing us closer comes in the form of new research into the origin and function of membranes—an essential step on the path from chemistry to life.

This particular piece of gap-filling comes from a paper published in PLOS Biology, authored by a team led by Professor Thomas Richards, Professor of Evolutionary Genomics in the Department of Biology at the University of Oxford. The researchers demonstrate that early cell membranes could not only have formed through natural processes, but also had the crucial ability to control what passed through them.

In doing so, they explain what had been something of a mystery and a favourite claim of ID creationists - the chirality of 'living' molecules where all amino acids have the same chirality. Creationists claim this shows the hand of an intelligent designer. This work shows it has a natural explanation.

Background: The Role of Membranes in Early Cells. Cell membranes are fundamental to life as we know it. They form a boundary between the internal environment of a cell and the outside world, allowing the cell to maintain homeostasis—an essential condition for life.

In the context of abiogenesis, the formation of the first cell-like structures (often called protocells) required more than just the right chemistry. It also required a way to compartmentalise reactions—something modern cells achieve through phospholipid bilayers that selectively allow substances in and out. For early life, however, these complex lipids were unlikely to be available. Instead, simple, spontaneously forming molecules like fatty acids are thought to have assembled into primitive membranes. These early membranes would have:

Enclosed a volume, allowing chemical reactions to occur in a controlled microenvironment.
Created a concentration gradient, enabling basic metabolic-like processes.
Allowed selective permeability, so essential molecules could enter while keeping larger or harmful ones out.
Provided structural integrity, helping protocells to grow, divide, and evolve.
Recent research, such as the study led by Prof. Thomas Richards, has shown that these early membranes could not only form naturally but also play an active role in facilitating prebiotic chemistry—bringing us a step closer to understanding how non-living chemistry gave rise to life.

Oxford’s Department of Biology provides more detail in an accompanying article:

How membranes may have brought about the chemistry of life on Earth
New research has explored why all life today uses building blocks with a certain 'handedness'. Led by Professor Thomas Richards, researchers studied the properties of membranes to understand how these cellular structures influenced the chemistry of life on Earth as it began.
How life arose remains a looming question in science that researchers are seeking to answer by studying the features shared among life today. Everything alive is made up of cells – and what made the first cells different from chemical reactions occurring in the environment is a membrane. By investigating what properties these early membranes may have had, scientists can better understand how life began and evolved into the diversity of organisms we have today.

An important feature of membranes is what they allow to pass through and what they stop from entering the cell. This influences which molecules are involved in the biological processes that keep cells ticking. The researchers focused on a few types of molecules essential for all life: the sugars that make up the backbone of DNA and RNA and the building blocks of proteins, known as amino acids. The researchers were interested in these molecules not only because they are so pervasive across life, but they also twist in specific ways.

An important feature of cell membranes is what they allow to pass through and what they stop from entering the cell.

Image: MarkusBlanke, Getty Images Pro

Biological molecules have a property called chirality, which refers to the way the molecule turns. It’s like comparing your left hand to your right hand; your hands are made up of the same structures, organised in fundamentally the same way, but flipped so that they are not identical. In biology, chirality is important for how molecules interact. For example, all the sugars in DNA and RNA need to have the same chirality (all be right-handed) to assemble into the backbone of a DNA or RNA strand. However, why life chose one chirality over the other has remained a lingering question. Tom says:

All known life uses a specific stereochemistry: left-handed amino acids and right-handed DNA. Understanding how this evolved is a long-standing mystery, key for understanding the origin of life. Our experiments show that a specific type of membrane – the structure that encloses cells – acts as a sieve that selects for the stereochemistry life uses.

Professor Thomas A. Richards, senior author
Department of Biology
University of Oxford, Oxford, UK.

The researchers propose that early membranes may have played a key part in selecting the right-handed sugars and left-handed amino acids that all life uses today. They analysed what was able to pass through membranes with properties similar to those of archaea, a major group of microbes. The researchers also tested a membrane they designed that mixes archaeal and bacterial properties. For both types of membranes, the right-handed DNA and RNA sugars more easily passed through, while the left-handed versions had trouble permeating.

There was more variability among amino acids. Some left-handed amino acids were more likely to pass through the membrane with mixed bacterial and archaeal properties. This included the amino acid alanine, which is thought to be one of the first amino acids used by life. Tom adds:

We were really shocked when different membrane types changed if left- or right-handed amino acids could pass through the membrane. When we found one membrane type that matched the compounds life uses, we were really excited..

Professor Thomas A. Richards.

While this study doesn’t paint a complete picture of the amino acids our cells use today, these findings demonstrate how differences in membranes strongly affect which amino acids are able to pass through. Since the membranes studied are only approximations of what the first life on Earth may have been encased in, there may be other, unknown properties of the earliest membranes that influenced what we now consider our most essential molecules.

Publication:
Goode O, Łapińska U, Morimoto J, Glover G, Milner DS, Santoro AE, et al. (2025)
Permeability selection of biologically relevant membranes matches the stereochemistry of life on Earth. PLoS Biol 23(5): e3003155. https://doi.org/10.1371/journal.pbio.3003155.

Abstract
Early in the evolution of life, a proto-metabolic network was encapsulated within a membrane compartment. The permeability characteristics of the membrane determined several key functions of this network by determining which compounds could enter the compartment and which compounds could not. One key feature of known life is the utilization of right-handed d-ribose and d-deoxyribose sugars and left-handed l-amino acid stereochemical isomers (enantiomers); however, it is not clear why life adopted this specific chirality. Generally, archaea have l-phospholipid membrane chemistries and bacteria and eukaryotes have d-phospholipid membrane chemistries. We previously demonstrated that an l-archaeal and a d-intermediate membrane mimic, bearing a mixture of bacterial and archaeal lipid characteristics (a ‘hybrid’ membrane), displayed increased permeability for several key compounds compared to bacterial-like membranes. Here, we investigate if these membranes can drive stereochemical selection on pentose sugars, hexose sugars, and amino acids. Using permeability assays of homogenous unilamellar vesicles, we demonstrate that both membranes select for d-ribose and d-deoxyribose sugars while the hybrid membrane uniquely selects for a reduced alphabet of l-amino acids. This repertoire includes alanine, the plausible first l-amino acid utilized. We conclude such compartments could provide stereochemical compound selection matching those used by the core metabolism of life.

Introduction
Life on Earth is defined by a curious and universal stereochemical asymmetry [1,2]. Specifically, the pentose sugars utilized for DNA and RNA (deoxyribose and ribose) possess three stereocenters imposing a d- (right-handed) stereochemistry. In contrast, 19 of the 20 universal proteinogenic amino acids possess one or two stereocenters imposing l- (left-handed) stereochemistry on polypeptides. A number of abiotic processes have been proposed for generation of homochiral states (e.g., [1–6]), while other works suggest stereoselectivity for the transfer of l-configured aminoacyl residues in tRNA [7–10]. Importantly, autocatalytic polymerization of mononucleotides proceeds with efficacy in mixtures with high relative ratios of one enantiomer [11]. Similar catalytic processes have been demonstrated for amino acids, which can polymerize stereo-selectively in abiotic conditions [3,12]. These data demonstrate Wald’s conjecture [1], which set out how the polymerization characteristics of ribonucleotides and amino acids would lead life to preferentially adopt a single stereochemical form. While these data explain why life might use homochiral states, they do not explain the conditions under which specific homochiral mixes arose in a biologically proximate system.

Numerous ideas about the origin of life have been influenced by the demonstration that abiotic chemical conditions can generate many compounds utilized by living systems (see [13]). Experimentally simulated prebiotic conditions have been shown to form ribose through the formose reaction [14], while a single abiotic phosphorylation mechanism can account for the phosphorylation reactions found across core metabolism [15], including the production of ribose-5-phosphate. The distribution of variant glycolysis pathways across the tree of life [16,17] also suggests that glycolysis was an ancestral feature of the last universal common ancestor (LUCA) [18,19]. Consistent with the phylogenetic age of these pathways, experimental chemical simulations of the early Earth ocean led to the formation of glycolysis intermediates [20], suggesting glycolytic pathway compounds were available for catabolism and as precursors of both ribonucleotides and phospholipids. Additional work has suggested that gluconeogenesis preceded glycolysis [21] and, therefore, glucose, and possibly other hexose sugars, were available for early life forms. Similarly, the Miller experiments [22,23] demonstrate that a subset of amino acids can form in simulated early Earth conditions. These experiments demonstrate glycine and alanine are generated at much higher concentrations than any other proteinogenic amino acid. Furthermore, alanine has been shown to form abiotically via transamination of oxaloacetate when exposed to a diverse range of cation catalysts [24]. A similar amino acid composition to those recovered in the Miller experiments has been detected in meteorite-derived materials [25]. These meteorite data provide important ‘outside-the-lab’ demonstrations that chemical compounds relevant for proto-metabolic function can form in abiotic conditions.

[…]

… The aim of this work is to test the hypothesis that membrane chemical characteristics impose permeability selection on enantiomers. We compare the enantiomer permeability of four pentose sugars, two hexose sugars, and 12 amino acids, demonstrating strong selection for d-ribose and d-deoxyribose in both the diether isoprenoid membrane types tested but no difference in permeability in the bacterial type diester fatty acid membranes. In contrast, only the hybrid membrane shows permeability selection for multiple l-amino acids, including strong selection for l-alanine, the candidate first chiral amino acid used [26,27]. We, therefore, suggest that early utilization of a ‘hybrid’ membrane chemistry—a possible precursor form to either, or both, bacterial or archaeal membrane chemistry—or an alternative unidentified membrane form with similar permeability characteristics, could have allowed enrichment of specific enantiomers and therefore hardwired life to utilize l-amino acids and d-ribonucleotides.

Goode O, Łapińska U, Morimoto J, Glover G, Milner DS, Santoro AE, et al. (2025)
Permeability selection of biologically relevant membranes matches the stereochemistry of life on Earth. PLoS Biol 23(5): e3003155. https://doi.org/10.1371/journal.pbio.3003155.

Copyright: © 2025 The authors.
Published by PLoS. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

The significance of this new research lies in how it strengthens the naturalistic framework for life’s origins. For decades, the emergence of functional, selectively permeable membranes has been a major open question in abiogenesis research. Without such membranes, primitive chemistry could not become compartmentalised—one of the critical steps from non-life to life. This study shows that simple, naturally occurring molecules could spontaneously form stable membranes and that these membranes could exhibit selective permeability. In other words, early membranes could not only arise without intelligent intervention, but also perform functions essential to early metabolic processes.

Perhaps more striking is that the membrane’s properties in this study offer a plausible explanation for one of biology’s most persistent mysteries: chirality. Biological molecules such as amino acids and sugars are consistently found in either left-handed (L) or right-handed (D) forms—but not both. This uniformity, known as homochirality, is crucial for molecular interactions in living systems. The research suggests that membrane environments might have influenced which chiral forms of molecules accumulated or reacted more efficiently, thus providing a natural mechanism for the emergence of homochirality—something that creationists often cite as inexplicable by natural means.

This undermines yet another of the so-called “impossible” hurdles in the origin of life narrative often touted by creationists. Their argument is typically framed as a false dichotomy: “If science doesn’t yet have a complete explanation, then God must have done it.” But every advance in abiogenesis research—like this one—shows how natural processes can account for what was once mysterious, removing the need to invoke supernatural explanations.

In short, the study closes yet another gap in our understanding of life’s origins, and with it, one more “God of the gaps” argument collapses under the weight of empirical evidence. As with so many gaps before, the membrane problem turns out not to be a barrier to naturalistic explanations, but rather another puzzle science is steadily solving.

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