All life on Earth can be traced back to one, likely hardy, single-cell organism, writes Marcelo Gleiser in a commentary at NPR.
Rather than gleaning evidence from ancient fossils, Gleiser says our Last Universal Common Ancestor (LUCA) was instead teased out from existing genetic material. Heinrich Heine University's William Martin and his colleagues sifted through the genomes of archaea and bacteria to find genes that they share that would suggest a common origin. Martin and his team reported in Nature Microbiology back in 2016 that they uncovered 335 protein families that they could trace back to LUCA.
They added in their paper that because those shared protein families weren't universally distributed, they could use that information to get a glimpse of some of LUCA's properties. It was, they said, anaerobic, able to fix carbon dioxide, and thermophilic, among other properties. This led the researchers to believe that LUCA dwelled near hydrothermal vents in the ocean, Gleiser adds, noting that some critics say LUCA might've originated on land before moving to the seas.
"For the moment, evidence points to our microbial Eve as a tough underwater organism, able to thrive in very hard conditions. We should expect this from any organism that branched out to become every other creature that ever lived. Talk about genetic legacy!" he adds.