nd in so doing invented posynte,posyntedly t important single metabolic innovation in toryof life on t”—and it ed not by plants but by bacteria.

    As cyanobacteria proliferated to fill o ternation of t found it poisonous—ually useoxygen to kill invading bacteria. t oxygen is fundamentally toxic often comes as a surpriseto t so convivial to our  t is only because  it. to ot is a terror. It is urns butter rancid and makes ironrust. Even olerate it only up to a point. t atentmosphere.

    tages. Oxygen  oproduce energy, and it vanquisitor organisms. Some retreated into ttoms. Ot ter (mucer)migrated to tive tracts of beings like you and me. Quite a number of tities are alive inside your body rigo digest your food, but abiniest  of O2. Untold numbers of oto adapt and died.

    teria  first, tra oxygen taccumulate in tmosp combined o form ferric oxides, tom of primitive seas. For millions of years, terally rusted—a ps t provide so mucoday. For many tens of millions of years not a great deal more t back to t early Proterozoic  find many signs of promise forEarture life. Perered pools you’d encounter a film of livingscum or a coating of glossy greens and broherwise life remainedinvisible.

    But about 3.5 billion years ago sometic became apparent. ructures began to appear. As t tines, teria became very sligacky, and t tackiness trappedmicroparticles of dust and sand, o form slig solidstructures—tromatolites t ured in ter on VictoriaBennett’s office romatolites came in