What is it about?

In the past, scientists have been unable to determine the precise chemical composition of the tiniest minerals present in rocks and sediments that are millions of years old. That inability to examine the oldest geological samples on Earth at what is called nano-scale has limited what scientists can know about how and when early life appeared on our planet after its formation, and also about life in other planets like Mars. We have devised a method to examine the composition of minerals that are a thousand times smaller than the average thickness of a single strand of human hair. We do this by using the technique of atom probe tomography, which allows us to analyze the chemical elements at the atomic level inside minerals, looking for the presence of carbon and nitrogen, which compose the basic building blocks for life on our planet.

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Why is it important?

This revolutionary approach to examining the tiniest minerals found in rocks and sediments that are produced by life forms will enable scientists to make advancements on two key fronts. The first is that it moves scientists one step closer to determining the origin of life in our planet. The second is that this method will allow scientists to test rocks and other geological samples from other planets, such as Mars, for evidence of life. It is expected that by the end of this decade scientists will have access to geological samples from Mars that can contain nano-scale minerals formed by organisms. Ultimately, our novel approach can answer questions about when life was present after the formation of our planet and other Earth-like planets in the Solar System.

Perspectives

Previous studies that have argued for a link between the origin of life and minerals have been based on circumstantial evidence. Our approach provides the smoking gun that enables scientists to actually visualize direct evidence of that link. This can unlock a lot of valuable data about how life appeared millions of years ago on Earth and can raise questions about what constitutes life on other planets.

Alberto Perez-Huerta
University of Alabama

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This page is a summary of: Biogeochemical fingerprinting of magnetotactic bacterial magnetite, Proceedings of the National Academy of Sciences, July 2022, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2203758119.
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