Shallow lake in Canada may hint at origin of life on Earth

(CNN) — Imagine a completely sterile world. Before you is a volcanic landscape, devoid of flora and fauna. Shallow water reservoirs are scattered throughout this brown and black expanse. In each of these natural pools, a precise combination of chemicals and physical conditions is created that can serve as a source of life on our planet.

Some scientists have theorized that when life first emerged on Earth about 4 billion years ago, the scene may have looked much like this rather than an ocean scene, and a study conducted at a modern-day site in the Canadian province of British Columbia Centered on the lake. Provides new support for that idea.

According to study co-author David Catling, a shallow, salty reservoir of water located above volcanic rock, known as Last Chance Lake, holds clues that carbonate-rich lakes on ancient Earth were “the cradle of life.” “Must have been. Professor of Geology at the University of Washington. The findings, published Jan. 9 in the journal Nature, could advance scientific understanding of how life began.

“We were able to look at the specific conditions that people use to synthesize the building blocks of life in nature,” Catling said. “We think we have a very promising place for the origin of life.”

British Columbia’s Last Chance Lake, taken during the rainy season in June 2022, has the highest levels of concentrated phosphate ever recorded in any natural water body on Earth. (David C. Catling)

Catling and his colleagues first became aware of the lake to focus their research on when a literature review revealed an unpublished master’s thesis from the 1990s that documented unusually high levels of phosphate there. Were done. But researchers had to see it for themselves.

last chance lake

Last Chance Lake is no more than 1 foot deep. Located on a volcanic plateau in British Columbia at more than 1,000 meters (3,280 ft) above sea level, it contains the highest levels of concentrated phosphate ever recorded in any natural body of water on Earth.

Haas shows a slice of dry-season lake bed taken from Last Chance Lake in September 2022. Researchers used the lake as an “analog environment” to understand soda lakes on the early Earth. (David C. Catling)

An important component of biological molecules, phosphate is a chemical compound that contains phosphorus, the element that sustains life. It is found in molecules such as RNA and DNA, as well as ATP, a molecule essential for energy production in all forms of life. The abundance of phosphate in Last Chance Lake is 1,000 times greater than in oceans or lakes, according to Sebastian Haas, a postdoctoral researcher who studies the microbiology and chemistry of aquatic environments at the University of Washington, who led the paper. ,

Between 2021 and 2022, the team of researchers visited Last Chance Lake to collect and analyze water and sediment samples.

That’s when they discovered that Last Chance Lake is a hot spot not only for phosphate, but also for the mineral dolomite, which allows phosphorus to accumulate in this environment and is formed through a reaction between calcium, magnesium and carbonate in the lake. Was made in response. The overall chemical processes affected by the minerals in the volcanic rock on which the lake formed, as well as the dry climate, effectively produced unique concentrations of phosphate, a set of conditions that researchers believe once existed on Earth. Could lead to the emergence of life, according to Haas.

“We are adding credibility to the idea that this type of environment would be favorable for the origin of life and that it is plausible,” he said.

Last Chance Lake is not 4 billion years old, in fact it is estimated to be less than 10,000 years old. The site is simply a modern analogy, or a natural snapshot of the past that finally offers scientists an opportunity to better understand what the early Earth might have been like outside the laboratory.

Haas said, “There is every reason to believe that similar lakes may have existed on the first Earth about 4 billion years ago, because the volcanic rocks on which Last Chance Lake lies were originally a prerequisite for the formation of soda lakes. Are.” “And what we’re partly showing here is that soda lake water chemistry is the precondition for these high phosphate levels.”

darwin’s hot pond

“Soda lakes”, like Last Chance Lake, are shallow bodies of water filled with dissolved sodium and carbonates, like baking soda, which typically come from interactions between water and volcanic rocks. They can be found throughout the world, but are much less common than other brackish water bodies.

“These types of lakes have the highest phosphate levels that match the phosphates people use to make (the genetic molecule) in the lab,” Catling said.

When scientists attempted to replicate the chemical reactions that make biomolecules critical to the origin of life in the laboratory, the phosphate concentrations required were a million times higher than those normally found in the world’s natural water bodies.

“If there were such lakes on the ancient Earth, they would have had very high phosphate concentrations, just like Last Chance Lake,” Catling said.

Such water bodies have long been on scientists’ radar as potential sources of primitive life. In the 19th century, Charles Darwin first wrote about his “warm little pond” theory, which proposed that warm, shallow, phosphate-rich lakes may have been where the first molecules of life may have formed.

“Part of what (Darwin) envisions is these bubble ponds… like Yellowstone,” said Matthew Pasek, a professor at the University of South Florida who studies the chemistry and biological origins of phosphorus.

But that’s not the only popular theory about how life first appeared on Earth billions of years ago. Secondly, life began in deep-sea hydrothermal vents.

According to Pasek, who was not involved in the research, the new study adds to evidence supporting the warm small pond hypothesis.

“The main point that these ponds can have such high concentrations of phosphate is certainly reinforced by this finding,” he said. “And it shows, ‘This is the way it can happen.'”
Nevertheless, phosphate in large quantities is not the only substance necessary for the origin of life. That list of prerequisites also includes carbon and nitrogen sources as well as the appropriate chemical and physical elements (including the phenomenon known as the wet-dry cycle) to allow the formation of the necessary chemical compounds and reactions.

But the authors said they are not arguing that today’s Last Chance Lake has all the components needed for life to form, just that it has some of the key pieces.

“The existing Last Chance Lake does not contain many of the chemicals that we now believe were important for the origin of life,” Haas said, citing cyanide as an example. Previous studies suggest that an early version of soda lake may have contained this substance.

According to Woodward Fisher, a geologist at the California Institute of Technology who was not involved in the study, although the work “does not specifically resolve the question of where life originated,” it provides clues to the current environment on Earth’s surface. It highlights what “scientists can study” in more detail to better understand the mechanisms responsible for the establishment of life on our planet and potentially elsewhere.

Origin of life on Earth and beyond

If life did indeed originate in soda lakes on land rather than at the bottom of the ocean, that knowledge could, in theory, aid in the search for evidence of life beyond Earth.

“If you think life originated on the ocean floor, you can take a closer look at the subglacial oceans on the moons of Saturn and Jupiter,” Haas said. “But if you think that life originated on Earth’s land surface, planets like Mars may be much more important.”

The same type of rock formations that form soda lakes can be found on much of the surface of rocky planets like Mars, suggesting that life may have formed in a similar manner elsewhere in the universe.

“Understanding how life originated on Earth is very important to our search for life beyond Earth,” Haas told CNN. “A better understanding of how life originated on Earth allows us to search for life on other planets in the Solar System, or on the moons of other planets.”

Aurela Horn-Muller has reported for Axios and Climate Central. His book, “Devord: The Extraordinary Story of Kudzu, the Vine That Ate the South,” is due out in the spring.