One of the assumptions we often make when discussing extraterrestrial intelligence is that Earth must be close to the optimal environment for advanced life. But why should that be true? Earth is simply the planet that happened to produce us. There seems no reason to think it is the best possible cradle for intelligence. That led me to wonder what a truly “ideal” environment for a technological civilisation might look like.
The first thing that struck me was the host star. We tend to focus on sun-like stars because that is what we know, but K-class (orange dwarf) stars may actually be better. They are quieter, more stable and, crucially, live for tens of billions of years - far longer than our sun. If intelligence is a rare outcome of evolution, then simply having several times longer for it to emerge could make an enormous difference. Likewise, a civilisation would have far more time to recover from collapses, spread beyond its home world or simply continue existing.
The second thought was that perhaps one habitable planet isn’t the optimal arrangement at all. Imagine a system with two genuinely habitable worlds. Before even attempting interstellar travel, such a civilisation could become naturally multi-planetary. It would learn how to manage multiple worlds, develop interplanetary transport, and gain resilience against catastrophe. It is a far smaller evolutionary step to colonise another planet in your own system than to leap straight to another star.
Then another possibility occurred to me… what if there were not only two habitable planets in one system, but another inhabited stellar system only a few light-years away?
That changes the picture dramatically. Suddenly interstellar travel is no longer an abstract ambition. Perhaps indeed there is another civilisation to communicate with. Instead of developing entirely alone, two neighbouring civilisations might push one another forwards, much as neighbouring cultures have done throughout human history.
This led me to wonder whether the most successful interstellar civilisations might not emerge from the “best” planets at all, but from the best-connected parts of the galaxy. We often talk about the ‘Planetary Habitable Zone’, but perhaps there is also something like a ‘Galactic Habitable Network’: regions where long-lived stars, multiple habitable worlds, high metallicity and relatively close stellar spacing all coincide. Such places might produce not isolated civilisations but networks of them, with each helping to increase the resilience and longevity of the others.
If that were true, the galaxy might not contain a random scattering of intelligent species. Instead, there could be “civilisation oases” - clusters where conditions favour the emergence of interstellar communities, while vast regions remain largely empty or home only to isolated worlds.
Another question followed naturally: if such civilisations existed, how would they communicate?
The obvious answer is mathematics. Unlike language, mathematics isn’t tied to culture. Prime numbers, geometry and physical laws should be recognisable to any technological species. It seems the natural first bridge between minds that evolved on completely different worlds. But perhaps mathematics is only the beginning. Language describes experience, but it does not share it. No mathematical equation can tell you what it is like to see the colour red. If two species evolved with radically different senses and ways of perceiving reality, symbolic communication might always be limited. That made me think about biology instead…
Plants, fungi and microorganisms already produce molecules capable of profoundly altering perception. It begs the question: could an advanced civilisation engineer biological or chemical interfaces capable of inducing specific perceptual or conceptual states in another intelligent species? Rather than exchanging symbols, they might exchange structured experiences. There are some suggestive leads in that direction and I believe, if we wish to uncover profound truths, we must have the courage and open-mindedness to explore the area further.
As for the central question, I find it an interesting way of reframing the search for extraterrestrial intelligence: instead of asking simply how many intelligent civilisations there are, perhaps we should ask what environments give intelligence the greatest chance of surviving long enough to become part of something larger.
