Were large soda lakes the cradle of life

Were large soda lakes the cradle of life
by Robert Schreiber
Berlin, Germany (SPX) Mar 26, 2025

Phosphorus, alongside nitrogen and carbon, forms one of the fundamental building blocks for life on Earth. It is integral to DNA, RNA, and ATP-molecules essential for storing genetic information and fueling cellular processes. Yet despite its biological importance, phosphorus is comparatively scarce near Earth's surface, both today and in the distant past.

This scarcity presents a major question for researchers: how could life have emerged in an environment lacking sufficient phosphorus? Laboratory studies suggest that prebiotic chemistry, the set of reactions that precedes life, requires phosphorus concentrations around 10,000 times higher than what is typically found in natural waters.

Earth scientist Craig Walton, a researcher affiliated with ETH Zurich's Centre for Origin and Prevalence of Life (COPL), proposes a compelling explanation. He suggests that large soda lakes, which lack natural outlets and only lose water through evaporation, could have provided the necessary high-phosphorus environment for life to originate. His findings, recently published in *Science Advances*, explore the geochemical dynamics that could have supported this process.

In closed-basin soda lakes, phosphorus doesn't escape through flowing water but instead accumulates as water evaporates. Over time, this leads to exceptionally high phosphorus levels. Such conditions could persist even after life begins to consume the available phosphorus, offering a stable chemical environment conducive to early biological activity.

While earlier research from the University of Washington in 2020 hinted at soda lakes as potential cradles of life, Walton's study builds on that concept by focusing on lake size and inflow dynamics. According to Walton, small soda lakes would rapidly deplete their phosphorus reserves once life emerged, stalling further biochemical development. In contrast, large lakes with significant river inflow and no outflow retain phosphorus effectively, allowing concentrations to remain high enough to support life over extended periods.

Mono Lake in California serves as a modern analog. Roughly twice the size of Lake Zurich, it maintains consistently high phosphorus levels that support diverse microbial life. This stability is due to the continuous influx of phosphorus-rich water and the lack of any natural outlet, which prevents nutrient loss.

Walton and his team argue that such large, closed-basin lakes could have served as optimal environments for the origin of life on early Earth. These lakes not only provided abundant phosphorus but also maintained it at levels suitable for both prebiotic chemistry and the development of living organisms. The new hypothesis challenges earlier ideas, such as Charles Darwin's concept of life beginning in small, shallow pools.

"This new theory helps to solve another piece of the puzzle of the origin of life on Earth," says Walton.

Research Report:Large closed-basin lakes sustainably supplied phosphate during the origins of life