Decades of research have left many unanswered questions about the origins of life and early evolution. A recent paper from UC Riverside has the potential to broaden our understanding and shape future studies that could contribute to predicting climate change and advancing the search for extraterrestrial life.
Christopher Tino, a UCR PhD candidate and first author of the paper, emphasized its role in guiding the Earth sciences community in determining the next steps for research.
While numerous studies have examined evidence of ancient life preserved in rocks, this paper integrates this information with genomic studies of modern organisms and recent advancements in understanding the changing chemistry of early oceans, atmosphere, and land masses.
The paper shows how the earliest life forms on Earth, such as O2-producing bacteria and methane-producing archaea, played a role in and were influenced by changes in the oceans, continents, and atmosphere.
“The central message in all of this is that you can’t view any part of the record in isolation,” said Timothy Lyons, a UCR distinguished professor of biogeochemistry and co-first author. “This is one of the first times that research across these fields has been stitched together this comprehensively to uncover an overarching narrative.”
Drawing on the expertise of specialists in biology, geology, geochemistry, and genomics, the paper comprehensively chronicles the evolution of Earth’s early life forms, from their initial emergence to their ascent to ecological dominance. As microbial populations grew, microbes started to impact the environment, such as by initiating the production of oxygen through photosynthesis.
According to Tino, a postdoctoral associate at the University of Calgary, the findings in each field consistently converge in striking ways, underscoring the coherence and synergy of the research across diverse disciplines.
This study examines how microbial life has played a crucial role in consuming, transforming, and dispersing key nutrients such as nitrogen, iron, manganese, sulfur, and methane across the Earth. These biological pathways have evolved alongside significant changes to Earth’s surface, including the emergence of continents, the increasing brightness of the sun, and the enrichment of the planet with oxygen.
The evolution of these biological pathways has had a profound impact on element cycles, providing valuable insights into the emergence of early life forms, their interaction with the environment, and the development of global-scale ecological footprints.
While rocks dating back billions of years often lack visible fossils, this study has ingeniously integrated the chemistry of these rocks and the genomes of living relatives to provide a comprehensive understanding of ancient life.
“In essence, we are describing Earth’s first flirtations with microbes capable of changing the global environment,” said Lyons, who is also the director of the Alternative Earths Astrobiology Center in the Department of Earth and Planetary Sciences. “You need to understand the whole picture to fully grasp the who, what, when, and where as microbes graduated from mere existence to having a significant effect on the environment.”
The history of life on Earth is a complex and fascinating story. Research shows that the rise of certain microbes from mere existence to dominance took hundreds of millions of years. This highlights the long journey that life forms took to become the “big kids on the block.”
Understanding our origins and the evolution of life is crucial, but the practical applications of this research are equally important. The insights gained can help us anticipate and respond to the impacts of climate change in the short term and far into the future.
The study could also aid the search for life on other planets. “If we are ever going to find evidence for life beyond Earth, it will very likely be based on the processes and products of microorganisms, such as methane and O2,” said Tino.
“We are motivated by serving NASA in its mission,” Lyons noted, “specifically to help understand how exoplanets could sustain life.”
Journal reference:
- Timothy W. Lyons, Christopher J. Tino, Gregory P. Fournier, Rika E. Anderson, William D. Leavitt, Kurt O. Konhauser & Eva E. Stüeken. Co‐evolution of early Earth environments and microbial life. Nature Reviews Microbiology, 2024; DOI: 10.1038/s41579-024-01044-y
