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In Earth's ancient history, microbes have been revered as the most primitive life forms, and the evidence of their existence is deeply embedded in rocks 3.5 billion years ago. These rocks, like the amber of time, seal geochemical and morphological markers, including the unique compounds and structures left behind by ancient organisms. However, the question of when and where life originated, and when these early microbial communities exhibited species diversity, remains a mystery. Due to the scarcity of evidence, this issue has also sparked much controversy.
Now, a new study led by a team of researchers from the University of Göttingen and Linnius University in Sweden has revealed key findings about the earliest life forms. Among the rock samples they found in South Africa, they traced back to about 34200 million years ago, evidence of an unprecedented diversity of microbial carbon cycles. This discovery suggests that during the Paleozoic period of the Earth, ecosystems were already home to complex microbial communities. The landmark study has been published in the journal Precambrian Research. The researchers analysed well-preserved particles of carbonaceous matter – altered remains of organisms – as well as corresponding rock formations from samples from the Barberton Greenstone Belt, a mountain range in South Africa whose rocks are among the oldest on the Earth's surface. Scientists have combined macro and micro analyses to clearly identify the original biological traces and distinguish them from later pollution.
The mountainous region of the Barberton Greenstone Belt in South Africa. Axel Hoffman.
They accurately characterize the geochemistry of a variety of microbes, including those that depend on sunlight, metabolize sulfate for energy, and potentially release methane. By skillfully combining geochemical data with microscopic observations of rock structures, the researchers revealed the unique role of these microbes in the ancient carbon cycle. "Just like looking for traces of carbonaceous material in a complex primary pyrite crystal and delving into the carbon and sulfur isotopes therein, we were able to distinguish the unique metabolic processes of each microorganism," explains Dr. Henrik Drake of Linn US University, senior author of the study.
Dr. Manuel Reinhardt, first author from the Earth Science Center at the University of Göttingen, added: "We unexpectedly found traces of microbial metabolism in this study, which is like looking for a needle in the middle of nowhere. This study sheds light on the mysteries of the Earth's early ecosystems. ”
Our findings have greatly deepened our understanding of ancient microbial ecosystems and opened up new horizons for research in the field of paleontology. This is not only a scientific breakthrough, but also a profound insight into the history of the earth and the origin of life. Reference: "c. 34Aspects of the biogenic carbon cycle in 200 million years of marine ecosystems", by M reinhardt， v. thiel， j.-p.duda、a. hofmann、d. bajnai、w. goetz、a. pack、j. reitner、m. schanofski、j.Sch Nig, M. J. Whitehouse, and HDrake, January 12, 2024, Precambrian Research.
doi： 10.1016/j.precamres.2024.107289