In Greg Fournier’s line of work — studying living systems that developed billions of years ago — outstanding questions far outnumber established answers.
With a keen interest in the evolutionary relationships among living things, Fournier started to focus in graduate school on microbes and their metabolisms, many of which are connected to major life-supporting processes on Earth, including the production of oxygen through photosynthesis. Continuing in that area, last year he and his research team were able to estimate that photosynthesis evolved between 3.4 and 2.9 billion years ago. This process — “one of the most important metabolisms to ever evolve,” according to Fournier — represented a huge step toward Earth’s habitability and occurred when microbes called cyanobacteria developed the ability to turn sunlight and water into energy, releasing oxygen.
To reach this discovery, Fournier’s team developed a new technique to analyze genes, tracing living species of cyanobacteria back to a common ancestor that evolved about 2.9 billion years ago.
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By understanding Earth’s processes at the time when life first appeared, Fournier says we can better understand how life could begin on other planets: “Our work can help us to understand the time and evolutionary processes that can lead to that critical ‘ecogenesis’ stage, and to perhaps recognize it in other worlds.”
