>Recently I watched a show that talked about the age of this planet. It is much older than previously thought. The narrator mentioned how the earth has recycled itself many times over, and stated that for most of its’ history, there was no life. Then life happened, and ultimately evolved into us and all the other species and forms in existence now. What I want to know is, how can it be stated as fact that there was no life previously? How can we know that life didn’t exist many times and become extinct and all traces plowed back into the magma through plate tectonics? I love science.