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Imagine a completely barren world. Before you lies a volcanic landscape, devoid of flora and fauna. Scattered across this gray and black expanse are shallow bodies of water. Each of these natural pools creates a precise mix of chemicals and physical conditions that could serve as a source of life on our planet.
Some scientists have theorized that the scene may have looked something like this, rather than an ocean environment, when life first appeared on Earth about 4 billion years ago, and a study around a present-day lake in the Canadian province of British Columbia offers new insights. support for that idea.
The shallow, salty water located on volcanic rock – known as Last Chance Lake – holds evidence that carbonate-rich lakes in ancient Earth could have been a “cradle of life,” said co-author David Catling, a professor at the University of Washington. of geosciences. The finding, published in the journal Nature on January 9, could advance scientific understanding of how life began.
“We were able to look for the specific conditions that humans use to synthesize the building blocks of life in nature,” says Catling. “We think we have a promising place for the origin of life.”
Catling and his colleagues first became aware of the lake as a place to focus their research after a literature search revealed an unpublished master’s thesis from the 1990s that found unusually high phosphate levels there. But the researchers had to see for themselves.
Last Chance More
Last Chance Lake is no more than a foot deep. Located on a volcanic plateau in British Columbia, more than 1,000 meters (3,280 feet) above sea level, it contains the highest concentrations of concentrated phosphate ever measured in any natural body of water on Earth.
Phosphate, a crucial component of biological molecules, is a chemical compound that contains the life-sustaining element phosphorus. It is found in molecules such as RNA and DNA, as well as ATP, a molecule necessary for energy production in all life forms. The abundance of phosphate at Last Chance Lake is more than a thousand times greater than what is typical for oceans or lakes, according to Sebastian Haas, a postdoctoral researcher who studies the microbiology and chemistry of aquatic environments at the University of Washington and who led the paper.
Between 2021 and 2022, the team of researchers visited Last Chance Lake to collect and analyze water and sediment samples.
Then they discovered that Last Chance Lake is a hotbed not only for phosphate, but also for the mineral dolomite, which allows phosphorus to build up in this environment and which formed in response to a reaction in the lake between calcium, magnesium and carbonate. The compound chemical processes, influenced by minerals from the volcanic rock on which the lake formed, and an arid climate, effectively produced the unique concentrations of phosphate – a set of conditions that researchers believe could once have led to the emergence of life . The Earth, according to Haas.
“We add credence to the idea that these types of environments would be favorable for the emergence of life, and plausible,” he said.
Last Chance Lake isn’t 4 billion years old; it is estimated that it is less than 10,000 years old. The site is simply a modern analogue, or natural snapshot of the past that ultimately offers scientists the opportunity to better understand what primordial Earth may have looked like outside of a laboratory.
“There is every reason to believe that similar lakes would have formed on first land about 4 billion years ago, because the volcanic rocks that Last Chance Lake sits on are actually a prerequisite for soda lakes to form,” Haas said. “And what we’re showing here in part is that the chemistry of the soda lake water is the prerequisite for these high phosphate levels.”
Darwin’s warm little ponds
“Soda lakes” like Last Chance Lake are shallow bodies of water full of dissolved sodium and carbonate – much like baking soda – that typically result from interactions between water and volcanic rock. They can be found all over the world, but are much less common than other salty water bodies.
“These types of lakes have the highest phosphate levels that match what people use in the lab to make (genetic molecules),” Catling said.
When scientists have tried in a laboratory to recreate the chemical reactions that make the biomolecules key to the origin of life, the phosphate concentrations required are up to a million times higher than what is normally found in the world’s natural water bodies is found.
“If you had lakes like this on ancient Earth, they would have a lot of phosphate, just like Last Chance Lake,” Catling added.
Water bodies like these have long been on scientists’ radar as potential sources of primordial life. In the 19th century, Charles Darwin first wrote about his “warm little pond” theory, which proposed that warm, shallow, phosphate-rich lakes might have been where the first molecules of life emerged.
“Part of what (Darwin) envisions are these bubbling pools … like Yellowstone,” said Matthew Pasek, a professor at the University of South Florida who studies phosphorus chemistry and the origins of the life sciences.
But this isn’t the only popular theory about how life first appeared on Earth billions of years ago. Another is that life began in hydrothermal vents in the deep sea.
The new study adds to the evidence supporting the warm little pond hypothesis, said Pasek, who was not involved in the research.
“The key point, that you can have such high phosphate concentrations in these ponds, is certainly supported by this finding,” he said. “And it shows, ‘This is how that can happen.’”
Yet phosphate in large quantities is not the only substance necessary for the emergence of life. That list of requirements also includes carbon and nitrogen sources, as well as the right chemical and physical elements – including phenomena known as wet-dry cycles – that enable the formation of necessary chemical compounds and reactions.
But the authors said they are not claiming that today’s Last Chance Lake contains all the components needed for the building blocks of life — only that it contains a few crucial parts.
“Today’s Last Chance Lake does not contain any of the chemicals that we now think are likely critical to the origins of life,” Haas said, citing cyanide as an example. Previous studies suggest that an original version of the soda lake could very well contain the substance.
While this work “does not uniquely resolve the question of the origins of life,” said Woodward Fischer, a geobiologist at the California Institute of Technology who was not involved in the study, “today it illuminates the Earth’s surface environments that scientists can study in more detail to better understand the mechanisms responsible for the origins of life on our planet and possibly elsewhere.”
The origin of life on Earth – and beyond
If life really did arise in soda lakes on land, rather than at the bottom of the ocean, that knowledge could theoretically help in the search for evidence of life beyond Earth.
“If you thought life originated at the bottom of the ocean, you might want to take a closer look at the subglacial ocean on the moons of Saturn and Jupiter,” Haas said. “But if you think life originated on Earth’s land surface, planets like Mars may be much more important.”
The same type of rock formation that produces soda lakes is found on much of the surface of rocky planets like Mars – suggesting that life elsewhere in the universe may have formed in a similar way.
“Understanding how life originated on Earth is of great importance to our search for life beyond Earth,” Haas told CNN. “By gaining a better understanding of how life originated on Earth, we can search for life on other planets, or moons of other planets, in the solar system.”
Ayurella Hoorn-Muller has reported for Axios and Climate Central. Her book “Devoured: The Extraordinary Story of Kudzu, the Vine That Ate the South” will be published this spring.
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