even before fire, organisms could only become more complex as the energy available to them increased Heck, look at how the complexity of life increased as soon

even before fire, organisms could only become more complex as the energy available to them increased Heck, look at how the complexity of life increased as soon as mitochondria were invented, going from genomes measured in millions of base pairs for bacteria to billions for amoebas once cells were no longer caught in the square/cube trap of respirating over the cell wall.