Answer:
The earliest life forms we know of were microscopic organisms (microbes) that left signals of their presence in rocks about 3.7 billion years old. The signals consisted of a type of carbon molecule that is produced by living things
But many researchers studying sleep and dreams believe there is a primary purpose to our dreams. Some theories suggest that dreams are: A way to process memory and learning, moving memories from short-term to long-term storage and giving the brain a clean slate