C&EN talks with Julie Cosmidis, geobiologist

Abstract

A world away, the Perseverance rover is traversing the Martian surface and stashing samples of rock. Planetary scientists can’t wait to get their hands on that cache, which NASA hopes to bring to Earth in the early 2030s. In the meantime, Julie Cosmidis is warning her colleagues not to jump to conclusions based on very limited data—because chemistry can create near copies of life without any help from biology. In a review published last year, Cosmidis, who studies biominerals at the University of Oxford , and coauthor Sean McMahon of the University of Edinburgh shared how the history of the search for life on early Earth and on other planets has been littered with blunders. They cited errors as far back as the 1800s, when sinewy filaments observed in rocks were mistaken for ancient organisms ( J. Geol. Soc. 2021, DOI: 10.1144/jgs2021-050 ). Cosmidis’s lab works to identify how certain