...he takes that line of questioning a step further, asking, how has life shaped and been shaped by our planet? He visits the largest living stromatolite fields, examples of how cyanobacteria began belching oxygen into the atmosphere as they converted carbon dioxide and water into living matter using the sun's light. The extraordinary increase in oxygen in the atmosphere resulted in an explosion in the diversity of life. And so began a riotous tangle of coevolution between plants and animals, as each changed the environment around them allowing others to utilise these new ecosystems and thus new species to evolve. From cyanobacteria, through algae on to ferns or trees or grasses, and from protists , through invertebrates and fish through the dinosaursand on to birds and mammals – our planet has seen an explosion of life forms, all reacting to their environment and all creating new environments that allow other life to evolve.