*millions, not billions. Earth is about 4.5B years old, life is about 3.7B years old, multicellular life (including life with neural nets) is about 600 million

*millions, not billions. Earth is about 4.5B years old, life is about 3.7B years old, multicellular life (including life with neural nets) is about 600 million years old. I don't think the span from microbe to multicellular organism counts in brain evolution.