Where did life on Earth get its start? In a newly published study, researchers from the University of Washington argue that carbonate-rich lakes would have been the best place for life’s chemical building blocks to come together.

The key to the argument is the availability of phosphorus, which is an essential element for organic processes but would have been scarce on ancient Earth. “For 50 years, what’s called ‘the phosphate problem’ has plagued studies on the origin of life,” Jonathan Toner, lead author of the study published in the Proceedings of the National Academy of Sciences, said today in a news release.

Toner and his co-author, UW Professor David Catling, dove into the problem and analyzed the water from carbonate-rich lakes around the world. Such bodies of water, known as soda lakes, form in dry regions where runoff and rapid evaporation create salty, alkaline water plus deposits of calcium carbonate. The chemical reactions result in phosphorus concentrations that can be 50,000 times higher than levels found in other types of lakes, in rivers or in oceans.

Toner said the higher carbon dioxide levels that existed on Earth 4 billion years ago could have supercharged such lake environments with phosphorus. “It solves the phosphate problem in an elegant and plausible way,” he said. So if astrobiologists ever get the chance to look for life on an alien planet, one of the first places they might want to visit is a soda lake.