Rosa Rubicondior: Refuting Creationism - The 'Abiogenesis Gap' Just Got a Little Bit Smaller

How urea forms spontaneously | ETH Zürich

Graphical representation of urea formation in a droplet.

Figure: Luis Quintero / ETH Zürich.

Creationism's ever-shrinking, gap-shaped creator god has just lost a little more ground. New research suggests that the formation of basic organic molecules may have been far easier under early Earth conditions than previously thought. Remarkably, scientists have found that urea—a key organic compound—can form spontaneously from ammonia and carbon dioxide on the surface of water droplets. This process requires no catalysts, no high pressure or heat, and consumes minimal energy.

Although vitalism was refuted as early as 1828 — decades before Darwin — creationists still claim that life cannot arise from non-living matter. Yet they quickly retreat when asked how dead food becomes living tissue, or what exactly they mean by ‘life’: a substance, a process, or some kind of magical force. In reality, life is a set of chemical processes, and at its core, it’s about managing entropy—using energy to maintain order against the natural drift toward disorder.

The discovery was made by researchers at Eidgenössische Technische Hochschule (ETH) Zürich in collaboration with colleagues from Auburn University in Alabama, USA. Their findings have just been published in Science.

Why Is Urea Important? Urea (CO(NH₂)₂) plays a pivotal role in theories about the origin of life because it contains both nitrogen and carbon—two essential elements for the formation of organic molecules. It is one of the simplest organic compounds that can be formed from inorganic precursors and is a key intermediate in the prebiotic synthesis of amino acids, nucleobases, and other biomolecules.

Historically, urea has symbolic importance in the development of modern chemistry. In 1828, Friedrich Wöhler famously synthesised urea from an inorganic salt (ammonium cyanate), showing for the first time that organic compounds could be made from non-living materials — undermining the 'vitalist' belief that organic substances could only be produced by living organisms.

In prebiotic chemistry, the spontaneous formation of urea under plausible early Earth conditions strengthens the case for a naturalistic origin of life. It suggests that the building blocks of life may have assembled in relatively ordinary environments, without the need for improbable conditions or supernatural intervention.

For a more accessible explanation, ETH Zürich has also summarised the study in a news release:

How urea forms spontaneously
Urea is considered a possible key molecule in the origin of life. ETH researchers have discovered a previously unknown way in which this building block can form spontaneously on aqueous surfaces without the need for any additional energy.

In brief

Urea is a fundamental industrial chemical and may have played a central role in the origin of life.
ETH researchers have discovered a new reaction: the spontaneous formation of urea on aqueous surfaces from carbon dioxide (CO₂) and ammonia (NH₃).
Its formation does not require catalysts, pressure or heat, illustrating how urea may have accumulated on Early Earth.
The reaction also has the potential for sustainable and low-energy urea synthesis.

Urea is one of the most important industrial chemicals produced worldwide. It is used as a fertiliser, for the production of synthetic resins and explosives and as a fuel additive for cleaning car exhaust gases. Urea is also believed to be a potential key building block for the formation of biological molecules such as RNA and DNA in connection with the question of the origin of life (see ETH News from 28 June 2023). Until now, the origin of urea itself on Early Earth has not been conclusively clarified.

A research team led by Ruth Signorell, Professor of Physical Chemistry at ETH Zurich, has discovered a previously unknown reaction pathway for the formation of urea that could provide an answer. The study has just been published in the journal Science.

Chemistry on the water surface

Either high pressures and temperatures or chemical catalysts are needed for the industrial production of urea from ammonia (NH₃) and carbon dioxide (CO₂). Enzymes enable the same reaction to take place in humans and animals, removing toxic ammonia from the breakdown of proteins such as urea. As this simple molecule contains nitrogen as well as carbon and probably existed on the uninhabited Early Earth, many researchers view urea as a possible precursor for complex biomolecules.
In our study, we show one way in which urea could have formed on the prebiotic Earth, namely where water molecules interact with atmospheric gases: on the water surface.

Professor Ruth Signorell, co-author
Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland.

Reactor on the edge of a droplet
Signorell's team studied tiny water droplets such as those found in sea spray and fine mist. The researchers observed that urea can form spontaneously from carbon dioxide (CO₂) and ammonia (NH₃) in the surface layer of the droplets under ambient conditions. The physical interface between air and liquid creates a special chemical environment at the water surface that makes the spontaneous reaction possible.

As a droplet has a very large surface area in relation to its volume, chemical reactions mainly take place near this surface. Chemical concentration gradients form in this area, which acts like a microscopic reactor. The pH gradient across the interfacial layer of the water droplets creates the required acidic environment, which opens unconventional pathways that would otherwise not take place in liquids.

The remarkable aspect of this reaction is that it takes place under ambient conditions without any external energy.

Mercede Mohajer Azizbaig, co-first author.
Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland.

This not only makes the process interesting from a technical perspective but also provides valuable insights into processes that could be significant for evolution.

A window into the early days of the Earth
The origin of life is currently the subject of a great deal of wide-ranging research, with different approaches being explored. First author Pallab Basuri explains:

Given such a controversial field of research, it was important for us to back up our observations.

Pallab Basuri, co-first author
Department of Chemistry and Applied Biosciences, ETH Zürich, Zürich, Switzerland.

Theoretical calculations by co-authors Evangelos Miliordos and Andrei Evdokimov from Auburn University supported the experimental findings and confirmed that the urea reaction on the droplets takes place without any external energy supply.

The results suggest that this natural reaction could also have been possible in the atmosphere of the Early Earth - an atmosphere that was rich in CO₂ and probably contained small traces of ammonia. In such environments, aqueous aerosols or fog droplets could have acted as natural reactors in which precursor molecules such as urea were formed.
Our study shows how seemingly mundane interfaces can become dynamic reaction spaces, suggesting that biological molecules may have a more common origin than was previously thought.

Professor Ruth Signorell.
In the long term, the direct reaction of CO₂ and ammonia under ambient conditions could also have potential for the climate-friendly production of urea and downstream products.

Abstract
Urea is a key molecule in the search for the origin of life and a basic chemical produced in large quantities by industry. Its formation from ammonia and carbon dioxide requires either high pressures and temperatures or, under milder conditions, catalysts or additional reagents. In this study, we observed the spontaneous formation of urea under ambient conditions from ammonia and carbon dioxide in the surface layer of aqueous droplets. Single, optically trapped droplets were probed by using Raman bands as markers. We found the surface layer to act like a microscopic flow reactor, with chemical gradients providing access to unconventional reaction pathways. This observation revealed a general mechanistic scheme for distinctive droplet chemistry. Interfacial chemistry is a possible nonenergetic route for urea formation under prebiotic conditions.

Mercede Azizbaig Mohajer et al.
Spontaneous formation of urea from carbon dioxide and ammonia in aqueous droplets.
Science 388, 1426-1430 (2025). DOI:10.1126/science.adv2362.

© 2025 American Association for the Advancement of Science.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.

This discovery adds yet another piece to the growing body of evidence that life’s basic chemistry can emerge under realistic, natural conditions—no divine intervention required. The spontaneous formation of urea in simple water droplets shows that even seemingly complex organic molecules can arise from unremarkable ingredients, given the right physical environment. It’s a reminder that the so-called "gaps" in scientific understanding—often exploited by creationists as supposed evidence for a creator—are steadily being closed by ongoing research.

Far from needing miraculous conditions, the chemistry that leads to life appears to be driven by the ordinary laws of physics and chemistry. Each new finding like this one shrinks the room for supernatural explanations and underscores how life may have arisen not as an extraordinary exception, but as a natural consequence of planetary processes.

For creationists, the implications are uncomfortable: if even molecules like urea, foundational to life’s chemistry, can form spontaneously in such simple settings, then the claim that life is too complex to have natural origins becomes even less tenable. As science continues to illuminate the path from chemistry to biology, appeals to mystery or miracle look increasingly like retreats rather than rebuttals.

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