Before the evolution of the present-day mutants, there were the old ones who slowly evolved from the young planet after the Ombryo (i.e. the original garden shrunk and died off). However, the life forms did not simply die off and the biosphere of Gaus fade into oblivion. It was part of the evolution-devolution cycle in nature. It was only natural that systems of lifeforms gradually rise up, reach a certain point, then devolve back down the cycle to gradually become extinct. Even as the Ombryo gradually died off, smaller systems and sub=systems gradually arose taking the place of the dying Ombryo. Simple colonies of the creatures in the original tropical garden began coming together to evolve into more complex colonies and organisms.