by Scientists published an article in the journal Science This answers questions about what the Earth looked like billions of years ago and what properties contributed to the origin of life. This research provides important information for understanding the origin of life and the search for life on other planets.
New research provides clues about the physical and chemical properties of Earth when life is thought to have originated.
About four billion years ago, the first signs of life appeared on earth in the form of microbes. Although scientists are still pinpointing exactly when and how these microbes arose, it is clear that the origin of life is intimately intertwined with the chemical and physical properties of early Earth.
“It’s reasonable to assume that life might have started differently – or not at all – had the early chemistry of our planet been different,” says Dustin Trail, associate professor of earth and environmental sciences at the University of Rochester.
But what did Earth look like billions of years ago, and what properties might have contributed to the emergence of life? In an article published in the magazine ScienceOn February 9, Trail and Thomas McCollom, a research associate at the University of Colorado Boulder, share key information to help find out. The research has important implications not only for discovering the origins of life, but also for the search for life on other planets.
“We are now in an exciting time as humanity searches for life on other planets and moons and in other planetary systems,” says Trail. “But we still don’t know how – or even when – life on our own planet began. Research like ours is helping to identify specific conditions and chemical pathways that may have aided the emergence of life, work that is sure to be prominent in the search for life beyond our planet.”
Rochester researcher Dustin Trail used experimentation and zircon chemistry to create more accurate computer models of fluids that act as pathways from the Earth’s interior to the Earth’s surface. With the models, researchers can simulate which metals – such as manganese (pictured) – might have been transported to the Earth’s surface when life first arose about four billion years ago. “Our research shows that metals such as manganese can act as important links between the ‘solid’ earth and emerging biological systems at the surface,” says Trail.
The importance of metals for the origin of life
The study of life and its origins typically spans a variety of disciplines, including genomics, the study of genes and their functions; proteomics, the study of proteins; and an emerging field called metallomics, which explores the important role of metals in performing cellular functions. As life evolved, the need for certain metals changed, but Trail and McCollom wanted to determine what metals might have been available when microbes first appeared billions of years ago.
“In general, when proposing hypotheses for different formation scenarios, scientists have assumed that all metals were available because there were no studies that provided geologically robust constraints on metal concentrations of liquids for the earliest periods of Earth’s history,” says Trail.
Billions of years ago, to fill this gap, Trail and McCollom studied the composition and properties of fluids in the lithosphere — the Earth’s outer layer, which includes the crust and upper mantle. These lithospheric fluids are key pathways for transporting dissolved fragments of rocks and minerals between the Earth’s interior and hydrothermal pools on the outside, where microbial life may have thrived. While researchers can’t directly measure the metals that existed billions of years ago, by determining the properties of the liquids they can infer which metals — and the concentrations of the metals — were between the Earth’s interior during the time when life was possible and the exterior might have emerged on the planet.
Clues in minerals billions of years old
Rocks and minerals billions of years old are often the only direct sources of information about Earth’s earliest history. That’s because rocks and minerals contain information about the composition of the Earth at the time it was formed.
The researchers performed high-pressure and high-temperature experiments and applied these results to early Earth zircons, a robust mineral species collected from sites in Western Australia, to determine the oxygen pressure, chlorine content and temperature of lithospheric fluids billions of years ago. They then enter this information into computer models. The models allowed them to simulate the properties of the lithospheric fluids and, in turn, simulate which metals might have migrated through the fluids to reach hydrothermal pools at the Earth’s surface.
Understand how life came about
The researchers were surprised by what the model simulations showed. For example, many origin researchers believe copper is a likely component in the chemistry that might have given rise to life. But Trail and McCollom found no evidence that copper was abundant under the constraints in their analysis.
One metal they tested that may have been available in high concentrations was manganese. While it is rarely factored into origin of life scenarios, today manganese helps the body form bones and assists enzymes in breaking down carbohydrates and cholesterol.
“Our research shows that metals such as manganese can act as important links between the ‘solid’ earth and emerging biological systems at the surface,” says Trail.
According to Trail, the research will help scientists studying the origin of life to feed more concrete data into their experiments and models.
“Experiments designed with this information in mind will lead to a better understanding of the origin of life.”
Reference: “Relatively oxidized fluids fed Earth’s earliest hydrothermal systems” by Dustin Trail and Thomas M. McCollom, February 9, 2023, Science.
DOI: 10.1126/science.adc8751
