The begins of life on earth has been a mystery for ages now but what we can do, is trace back its history to understand how it was when it might first have seen the light of the sun. There have been many different conditions through which life on earth have gone through and have been subject to but it has survived for almost 550 million years now and we hope that it will live on for even more centuries and ages.
Starting for the Phanerozoic Age which saw the birth of the first organisms on earth, till present age, the quality and quality of life has gone through various modifications and has sustained itself even after there has been instances of mass extinctions over the ages.