Our galaxy is "only" 50,000 lightyears across. 50k years is an eyeblink in cosmological terms. Behaviourally modern humans have been around about that long and

Our galaxy is "only" 50,000 lightyears across. 50k years is an eyeblink in cosmological terms. Behaviourally modern humans have been around about that long and it's too short a time for fossils to even form, except in extraordinary conditions. It's a thousandth of the time to the dinosaurs. I think that's reasonably up to date in evolutionary terms. Andromeda at 2.5m ly is a bit more of a stretch, but it's still a fairly short period in the history of life on Earth. It all depends on how long we think technological civilizations last on average. If they can reach sustainability it could be at least as long as their solar systems remains habitable, maybe hundreds of millions of years, even without interstellar travel.