People always act like it's a forgone conclusion that if there is alien life, they are logically way more advanced than us. There almost certainly is life outside of Earth, and it's probably a planet of sloths and sheep and plants. Human beings evolved due to pretty specific circumstances that may never happen again in the history of this universe or any other.
I think this is the really interesting part of the equation. Of all the different species that have resulted from evolution, humans are completely and totally unique in their consciousness and culture, and its really difficult to gauge how rare those traits would be.
Looking at earth on a timeline:
- 4.5 billion years ago the earth formed and
- 4 billion years ago basic single celled life formed (earth had to cool down and stuff), this starts photosynthesis which oxygenates the atmosphere
- 1.5 billion years ago, multi-cellular life finally forms. Most scientists think it took so long because because the planet was not quite warm enough (the sun wasnt as hot back then)
- 530 million (0.53 bil) years ago, the Cambrian explosion starts, evolution goes into overdrive and life proliferates and diversifies
- Modern humans come around about 200,000 years ago