"Are We a Second Genesis?" -- Earth's Hidden Alien Life
Has life started many times of Earth? Could life as we know it today on our pale blue dot in fact be a second genesis? Could Earth’s original microbial life have formed four billion years ago, only to be destroyed some ten million years later during the age of Late Heavy Bombardment by massive asteroids sterilizing the planet? But perhaps some of this primordial “life as we don’t it” survived the 200-million-year barrage of huge objects followed by a second genesis of microbial life representing our form of life co-existing to this day with a “shadow biosphere” of Earth’s original alien life forms.