Shallow Soda Lakes Could Be Strong Candidate for the Emergence of Life on Earth, Study Reveals

In 1871, in a letter to botanist Joseph Hooker, Charles Darwin wrote his speculations about the 'warm little pond.' It is a hypothetical terrestrial shallow water environment on young Earth under which the origin of life might have occurred. This theory remains one of the most suggestive explanations for the emergence of living organisms on our planet.

Primary Ingredients of Life

Experts have known that under the right combination of chemicals and energy, the complex molecules of life can spontaneously emerge. It was also recently fictionalized that biological molecules can be coaxed to appear from inorganic molecules.

Long after the discovery of amino acids, more studies were made on the building blocks of RNA. However, this step requires extremely high phosphate concentrations.

Phosphate is a chemical compound that forms the "backbone" of nucleic acids and is also a vital component of cell membranes. In the laboratory, the phosphate concentrations needed to create the biomolecules are hundreds to one million times higher than the levels normally found in lakes, rivers, or the ocean. This dilemma has been called the "phosphate problem" for the emergence of life.

Scientists believe that soda lakes could provide an answer to the phosphate problem. This environment might have occurred on the early Earth because it is a natural outcome of how planetary surfaces are made.

Soda lakes got their name from possessing high dissolved sodium and carbonate levels, the same components of dissolved baking soda. They are formed from the reactions between water and volcanic rocks beneath the surface. There is also a high chance that soda lakes contain high levels of dissolved phosphate.

Search for the Most Promising Candidate

In 2019, a previous study by the University of Washington discovered that the chemical conditions for the emergence of life could theoretically occur in soda lakes. Combining chemical models with laboratory experiments showed that natural processes can theoretically concentrate phosphate in soda lakes to levels up to one million times higher than in typical waters.

For the new study, UW scientists report that a shallow soda lake in western Canada shows promise for matching the requirements of a warm little pond. The highest known natural phosphate level was found at Last Chance Lake in inland British Columbia. Their research findings offer new insight into the emergence of life about 4 billion years ago.

Led by Sebastian Haas, the UW team visited the lake three times from 2021 to 2022 during the early winter, early summer, and late summer. They collected samples of lake sediment, water, and salt crust to determine its chemistry.

In most lakes, the dissolved phosphate combines quickly with calcium to form calcium phosphate. In Last Chance Lake, calcium combines with lots of carbonate and magnesium to create dolomite.

This reaction was predicted by the previous modeling work and was confirmed upon the discovery of high amounts of dolomite in Last Chance Lake's sediments. This finding supports the growing evidence that evaporative soda lakes meet the requirements for the origin of life by accumulating vital ingredients at high concentrations.