Hardly any debate about evolution with a creationist will go more than a few exchanges before the creationist gives up trying the traditional fallacies and avoidance tactics and falls back onto ground he or she feels safer on - abiogenesis - with the demand that you explain how the first cell arose fully developed, with the parrot squawk assertion that 'you can't get life from non-life'.
But ask them to define 'life' and they'll break off the debate because it's a term creationists think involves something that science can't explain, but they've no idea what it is or why it should present science with a problem. Ask them to explain how dead food becomes living tissue through the process of digestion and metabolism, if it's impossible, and you probably won't hear from them again.
The gap creationists are trying to shoehorn their favourite creator god into is what they've been programmed to believe is unclosable by science, so it must have been done by the locally popular god. They will of course be unaware of the fallacy of the false dichotomy because it's probably what someone fooled them with, so they just assume it'll work on everyone else.
What was the role of an enclosing membrane in early cells during abiogenesis? During abiogenesis, which is the hypothetical process by which life arises from non-living matter, the role of an enclosing membrane in early cells was crucial. One of the fundamental challenges in the origin of life is the transition from simple molecules to more complex, self-sustaining structures. Enclosing membranes, such as lipid bilayers, played a key role in this process for several reasons:So it must be terrifying to their cult leaders that science has been steadily closing that gap and shrinking the little god in it for several years now. And they just closed it a little more with the discovery by a team from Newcastle University, Newcastle upon Tyne, UK, that the basic units for making a membrane that was needed to separate the inside of primitive cells from the outside, can be made in the conditions which exist in geothermal hot springs. A simple cell membrane allows an electrochemical gradient to form and so provide energy to drive some basic metabolic functions.The formation of these early membrane structures is thought to have occurred spontaneously, driven by the inherent properties of certain molecules, such as lipids, in response to environmental conditions. Over time, these simple membrane structures could have encapsulated and facilitated the development of more complex biochemical systems, leading eventually to the emergence of life.
- Compartmentalization: Membranes create enclosed spaces, or compartments, which can concentrate and separate different molecules and chemical reactions. This compartmentalization is essential for the organization and specialization of biochemical processes, allowing for more efficient and controlled interactions among molecules.
- Chemical Isolation: The early Earth had a dynamic and often harsh environment. Enclosing membranes provided a barrier against external influences, helping to protect the internal chemical processes from disruptive external factors. This isolation would have allowed for the development of specific conditions conducive to the formation and maintenance of complex molecules.
- Concentration of Molecules: By enclosing a space, membranes allowed the concentration of specific molecules within that space. This concentration effect could have facilitated the formation of complex molecules and polymers, as the likelihood of molecular interactions increased.
- Energy Transduction: Membranes can also be involved in energy transduction processes. For example, the formation of proton gradients across membranes can lead to the generation of energy that could be utilized by the emerging cellular systems.
- Separation of Internal and External Environment: Membranes helped in creating a distinction between the internal environment of the primitive cell and the external environment. This separation is essential for the establishment of gradients, regulation of internal conditions, and protection of delicate biochemical processes.
These basic units consist of long-chain amphiphilic molecules, such as fatty acids, and the Newcastle team have shown that a range of functionalised long-chain aliphatic compounds, including mixed fatty acids up to 18 carbon atoms in length can be produced in a laboratory by mimicking the conditions in a geothermal hot spring with dissolved hydrogen and bicarbonate with the iron-rich mineral magnetite under conditions of continuous flow and alkaline pH even at relatively low temperatures (90 °C).
The team's research findings were published a few days ago in the journal, Nature Communications Earth & Environment and how they carried out the research is explained in a Newcastle University press release:
Newcastle University research turns to ancient hot springs to explore the origins of life on Earth.In the abstract and introduction to their open access paper in Nature Communications Earth & Environment the researchers say:
The research team, funded by the UK’s Natural Environmental Research Council, investigated how the emergence of the first living systems from inert geological materials happened on the Earth, more than 3.5 billion years ago. Scientists at Newcastle University found that by mixing hydrogen, bicarbonate, and iron-rich magnetite under conditions mimicking relatively mild hydrothermal vent results in the formation of a spectrum of organic molecules, most notably including fatty acids stretching up to 18 carbon atoms in length.
Published in the journal Nature Communications Earth & Environment, their findings potentially reveal how some key molecules needed to produce life are made from inorganic chemicals, which is essential to understanding a key step in how life formed on the Earth billions of years ago. Their results may provide a plausible genesis of the organic molecules that form ancient cell membranes, that were perhaps selectively chosen by early biochemical processes on primordial Earth.
Fatty acids in the early stages of life
Fatty acids are long organic molecules that have regions that both attract and repel water that will automatically form cell-like compartments in water naturally and it is these types of molecules that could have made the first cell membranes. Yet, despite their importance, it was uncertain where these fatty acids came from in the early stages of life. One idea is that they might have formed in the hydrothermal vents where hot water, mixed with hydrogen-rich fluids coming from underwater vents mixed with seawater containing CO2.
The group replicated crucial aspects of the chemical environment found in early Earth's oceans and the mixing of the hot alkaline water from around certain types of hydrothermal vents in their laboratory. They found that when hot hydrogen-rich fluids were mixed with carbon dioxide-rich water in the presence of iron-based minerals that were present on the early Earth it created the types of molecules needed to form primitive cell membranes.
Lead author, Dr Graham Purvis, conducted the study at Newcastle University and is currently a Postdoctoral Research Associate at Durham University.
Principal Investigator Dr Jon Telling, Reader in Biogeochemistry, at School of Natural Environmental Sciences, added:Central to life's inception are cellular compartments, crucial for isolating internal chemistry from the external environment. These compartments were instrumental in fostering life-sustaining reactions by concentrating chemicals and facilitating energy production, potentially serving as the cornerstone of life's earliest moments.
The results suggest that the convergence of hydrogen-rich fluids from alkaline hydrothermal vents with bicarbonate-rich waters on iron-based minerals could have precipitated the rudimentary membranes of early cells at the very beginning of life. This process might have engendered a diversity of membrane types, some potentially serving as life's cradle when life first started. Moreover, this transformative process might have contributed to the genesis of specific acids found in the elemental composition of meteorites.
Dr Graham Purvis. lead author
School of Natural and Environmental Sciences
Newcastle University, Newcastle upon Tyne, UK.Intriguingly, the researchers also suggest that membrane-creating reactions similar reactions, could still be happening in the oceans under the surfaces of icy moons in our solar system today. This raises the possibility of alternative life origins in these distant worlds.We think that this research may provide the first step in how life originated on our planet. Research in our laboratory now continues on determining the second key step; how these organic molecules which are initially ‘stuck’ to the mineral surfaces can lift off to form spherical membrane-bounded cell-like compartments; the first potential ‘protocells’ that went on to form the first cellular life.
Dr Jon Telling, corresponding author
School of Natural and Environmental Sciences
Newcastle University, Newcastle upon Tyne, UK
AbstractCreationists are clinging to the forlorn hope that, of all the gaps closed by science, where their god used to sit, the abiogenesis gap will turn out to be the one their god is finally found in. But of course, it never will be for the simple reason that no scientific explanation can ever include an unfalsifiable, unproven, supernatural entity because science deals with materialist reality. This is what concerns creationists most, hence their attempts to undermine and misrepresent materialism. Accepting a materialist explanation for everything removes gods from any and all explanations and also removes the excuses priests and preachers have for their existence.
The origin of life required membrane-bound compartments to allow the separation and concentration of internal biochemistry from the external environment and establish energy-harnessing ion gradients. Long-chain amphiphilic molecules, such as fatty acids, appear strong candidates to have formed the first cell membranes although how they were first generated remains unclear. Here we show that the reaction of dissolved hydrogen and bicarbonate with the iron-rich mineral magnetite under conditions of continuous flow, alkaline pH and relatively low temperatures (90 °C) generate a range of functionalised long-chain aliphatic compounds, including mixed fatty acids up to 18 carbon atoms in length. Readily generated membrane-forming amphiphilic organic molecules in the first cellular life may have been driven by similar chemistry generated from the mixing of bicarbonate-rich water (equilibrated with a carbon dioxide-enriched atmosphere) with alkaline hydrogen-rich fluids fed by the serpentinisation of the Earth’s iron-rich early crust.
Introduction
How inorganic geochemical substrates and catalysts ultimately resulted in the first set of organic molecular systems capable of energy harvesting and self-replication is central to understanding the origins of cellular life on the Hadean-Archaean Earth, >3.5 billion years ago. Cell membranes form boundaries, creating internal microenvironments that host metabolic activity and can sustain ion gradients driving CO2 fixation and energy metabolism, a functionality so deeply conserved that it suggests a role for membranes at the origin of life1,2,3,4,5,6,7. The production of some sort of lipid membrane was a pivotal step towards the emergence of cellular life and occurred early in the path from geochemistry to cellular biology8,9. Single-chain amphiphilic monocarboxylic acids (such as fatty acids) with ≥8 carbon atoms can spontaneously self-assemble into vesicles10,11 in aqueous solutions producing semi-permeable barriers that are strong candidates to have been selected as the primitive membranes of the first protocells8,12,13. Despite their importance, the source of the amphiphilic constituents of protocell membranes remains unresolved11,14,15,16,17,18,19.
One compelling potential environment for the origin of life is the mixing zone between bicarbonate and CO2-enriched seawater (and even potentially freshwater)19,20 and the upwelling hydrogen-rich fluids from alkaline hydrothermal vents (AHV)21,22,23,24, that are found today on the deep ocean floor17,25,26 shallow seas20,27, freshwater-tidal mixing zones18,20, and in terrestrial environments28,29,30 but were likely to have been more common on the Hadean-Archaean Earth31,32,33,34. The H2-rich fluids are primarily derived from the serpentinisation of ultramafic rocks, which on mixing with seawater generate far-from-equilibrium conditions conducive to inorganic carbon reduction35 to produce organic compounds36,37,38,39,40. Potentially, the organic compounds generated, including amphiphilic subunits of protocellular membranes, were selected by the precursor biochemistry on Haden-Archaean Earth6,41,42.
Organic compounds in modern AHV fluids of the Lost City hydrothermal vent field are dominated by C9–C14 aliphatic hydrocarbons, C6–C16 aromatic compounds and C8–C18 carboxylic acids, a fraction of which may have been produced abiotically35,43,44,45. Due to the oxygen-free CO2-rich atmosphere, and subsequent abundance of potentially catalytic Fe/Ni-minerals, organic molecular generation at Hadean-Archaean AHV counterparts may have been more efficient38,39,46. Prior electrochemical experiments using greigite (Fe3S4) at room temperature47 and higher temperature batch experiments in the absence of O2 using greigite, magnetite (Fe3S4) and awaruite (Ni3Fe) at temperatures ≥100 °C48,49 and Fe0, Ni0 and Co0 between 30 and 100 °C50 have shown that CO2 can be reduced to C1–C3 organic compounds, some including monocarboxylic acids. However, these experiments used fixed volumes of reactants, thus, the disequilibrium required for CO2 reduction would decay as the reaction proceeded. Continuous flow, bench-top electrochemical reactors51 and oceanic simulant fluids in microfluidic reactors generating pH gradients across Fe(Ni)S precipitates52 have also resulted in the production of formate. Additionally, the reduction of bicarbonate, assisted by cobalt oxides, promoted a carbon−carbon coupling process that generated hydrocarbons up to C24 long at ∼300 °C and 30 MPa53. However, no experiments have yet demonstrated the generation of ≥C8 long-chain fatty acids that are necessary for self-assembling protocell vesicles2,8 from H2 and HCO3− under AHV conditions at <100 °C.
We hypothesised that having both continuous flow and pressurised hydrogen would enable the generation of long carbon chain fatty acids on Fe-minerals. Therefore, we built a pressurised continuous flow reactor to more accurately mimic key elements of the chemistry of upwelling alkaline hydrothermal vent fluid and Hadean-Archaean surface water mixing. An HCO3− solution was mixed with dissolved H2 at concentrations comparable to modern and putative ancient AHV, kept in disequilibrium at 90 °C and 16 bar and passed over magnetite (Fe2O3), a mineral associated with AHV54 (Detailed method in Supplementary Methods). We used a range of complementary bulk and mineral surface-sensitive techniques to analyse the organic molecules generated in experiments, alongside monitoring changes in the inorganic chemistry.
Purvis, G., Šiller, L., Crosskey, A. et al.
Generation of long-chain fatty acids by hydrogen-driven bicarbonate reduction in ancient alkaline hydrothermal vents.
Commun Earth Environ 5, 30 (2024). https://doi.org/10.1038/s43247-023-01196-4
Copyright: © 2023 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
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