WIKIMEDIA, PAUL GIERSZEWSKIIn northeastern Canada, scientists have discovered what they believe are signs that bacterial life existed there 3.95 billions years ago—millions of years before the first fossils appeared in the geological record—according to a study published yesterday (September 27) in Nature.
Living organisms prefer the most common carbon isotope, 12C, to the rarer, heavier 13C for building their cells. Once decomposed, those 12C-rich organisms contribute to the 12C enrichment of their environment. Finding a sample, such as a mineral, enriched in 12C, therefore, can indicate that living organisms were present in the environment when that sample was formed. Study authors Yuji Sano and Tsuyoshi Komiya from the University of Tokyo found graphite enriched with 12C embedded within 3.95-billion-year-old rocks in Labrador.
This newly investigated graphite adds new evidence to the start of life on our 4.54-billion-year-old planet. As The Atlantic reports, the complexity of the oldest known fossils, dated to 3.7 billion years ago and found in southwest Greenland, indicates that life had arisen well before ...
