It's uncanny how many alien races encountered in Star Trek are at a comparable level of technological development: humans, Vulcans, Romulans, Klingons, + numerous other species. The likelihood of all these races independently evolving warp drive within a few thousand years of each other seems improbable.
Are there canonical explanations for this? A few possible answers (which may be supported by canon, I don't know):
- Advanced species share or involuntarily leak their technology with low-tech species.
- Advanced species "uplift" less evolved species as the Dominion did.
- Low-tech species are annihilated or absorbed into the empires/federations of expanding high-tech warp capable species. This continues until two or more advanced civilizations at the same military tech level eventually bump into each other.
- Most civilizations tend to stagnate once they hit a tech level say a few hundred or thousand years beyond our own.
- Many intelligent species either go extinct (eg, the Tkon and Iconian Empires) or evolve to a higher state of being (eg, the Zalkonians) soon after developing warp technology and leave our plane of existence or become aloof to mundane matters. This would conveniently clear out all civilizations that had evolved billions of years in the past up through several thousand years ago, and also explain the many god-like entities throughout the Galaxy.
Any other thoughts?