Currently, we can only extrapolate based on our own species’ evolution and that is usually viewed as a flawed method - a tiny window of time since we’ve achieved technologies that barely begin to permit our being noticed by other (more) advanced species.

Factoid - our species only began producing radio waves strong enough to reach out any distance from our solar system approx 50 years ago. That means our presence is only potentially known to a small fraction of our galaxy and only an infinitessimal fraction of the universe.

Factoid - our species has only been engaged in any concerted effort to scan the universe for inbound signals for a few decades, and we lack the ability to continuously monitor the entire universe on all frequencies.

Factoid - our species is only now close to identifying potential earths elsewhere in the universe. It may be hundreds of years before we can do much more than make educated guesses about what exists on them. Humans may be killed off or at least knocked back to the stone age before then, from nuclear war, global warming or a pandemic. Interesting read - http://www.space.com/scienceastronomy…

The probability of catastrophies befalling any species before they achiece a level of technology equal to our transmitting of radio waves (much less receive and decipher OURS) is likely very high.

The probability of a species evolving beyond that primitive level and achieving space travel/migration capabilities that might ensure its survival for eons is likely extremely low.

The scale of the universe is almost impossible for most people to grasp even now, much less back when Fermi speculated in 1950. To me, the assumptions made by Fermi weaken his premise, and in no way “prove” that humans are unique or that other intelligent species haven’t evolved or don’t exist now, nor whether they might have passed through this quadrant of the universe and perhaps even probed nearby star systems or tagged this system for future study (maybe by placing a monolith/beacon on an outlying planetoid that only transmits once every 1000 solar years) or even seeded this little planet with primitive organisms a billion years ago just for laughs.