Complex life may have started before Earth had much oxygen at all. A University of Bristol-led Nature study found that the ancient archaeal lineage behind all plants, animals and fungi began developing complex cellular machinery in anoxic oceans almost 2.9 billion years ago — nearly a billion years earlier than some scientists thought.

Complex life is usually told as an oxygen story. First Earth changed, then life became more complicated: oxygen rose, cells gained new energy options, and the long route toward plants, animals and fungi opened up. A University of Bristol-led Nature study makes that order less tidy. In the paper, Christopher J. Kay and colleagues argue [...] The post Complex life may have started before Earth had much oxygen at all. A University of Bristol-led Nature study found that the ancient archaeal lineage