It's pretty straightforward to trace our evolution back to single cells, but to rocks? And I don't think there is a clear idea of where viruses and stuff come i

It's pretty straightforward to trace our evolution back to single cells, but to rocks? And I don't think there is a clear idea of where viruses and stuff come in. I vaguely remember an article suggesting there might be a previously unknown mechanism used by the brain to handle memories that resembles (literal) viral machinery. Some think there might have been a biosphere before DNA, that used RNA. But presumably early life underwent transformations that wiped out the very first, whatever it was.