LIFE IN MUTUALISM:
IN THE BEGINNING PART ONE-THE TIMES OF GENESIS:
Life probably began about 3.8 billion years ago.during the Eoarchaen Era (4 > 3.6 Billion years ago).This is the approximate time that we find the oldest rocks of Earth. Before this time the surface of the Earth was molten, and hence there there is no recoverable record., This was the Hadean eon. The Eoarchaen era left few signs in the fossil record, but of those which remain there is at least some evidence of bacterial colonies. Why 'colonies' ? Why was life undetectable until the arrival of a colonial lifestyle ? It's a question that can presently have no definitive answer, but there is the distinct possibility that colonial forms of life had an advantage in terms of natural selection. Individual organisms no doubt evolved before the colonial forms that give the first fossil evidence of life.Yet, invoking nothing but natural selection it seems that "collections" of organisms had a selective advantage over those who remain as singular cells.
The evolution of a cooperative way of living, insofar as certain cellular organs such as mitochondria and chloroplasts were probably in place before the colonial stage came into being. But this is not necessarily so. It could be that the mass of a colonial group of organisms was an easier target for so-called parasites which later became indispensible to life.It would be interesting see if this question of priority will be addressed in the future. For the moment let us note that the earliest definite evidence of life is of "cells living together", and that these cells were either likely to become composites or were formed of cells that were already "mutualistic". Lets keep this in mind.