Aww, no alien empires yet

[Drashner1]

Your point about birth control and the like is well taken, but we can't know that it applies to all lifeforms. For an example where it doesn't apply because nobody has discovered effective birth control without undesirable side effects, see the Moties.

Another example of a sapient lifeform that wouldn't have the attitudes of humans might be one that produces huge numbers of offspring without investing much in them, and accepts enormous levels of infant mortality - much as Earth organisms such as amphibians and fish do. Sapient frogs wouldn't think like us in this respect - or many other respects, for that matter.

Possibly. But would any such lifeform survive long enough to produce an interplanetary civilization, let alone an interstellar one or a one capable of building a dyson sphere or equivalent? Personally, I never found the Moties particularly convincing, although I did enjoy the story itself. Modern genetic engineering makes them even iffier - why not engineer themselves to not need sex to survive? In many ways, I've always considered the Moties to have more to do with a commentary on the human condition and possibly Malthusian concerns of the day.

Coming at this from another direction, most thinking on advanced civs seems to assume that a civilization will build a dyson sphere (an idea from the 60s) and then just...stop. But would that actually be the case? What do they do with the next few thousand (or million) years? For that matter, since dyson's were conceived other options have been proposed. Both Matrioshka Brains and Criswell Structures would be rather harder to detect than Dyson Sphere's IIRC. And they might turn out to be nothing like the ultimate forms that advanced civs might end up taking.

Our searches keep turning up huge planets in extreme proximity to their stars - Jupiter brains built to suck up lots of solar energy?

IIRC Dyson suggested that sphere's might be built in a few thousand years or so. That's almost nothing compared to a million years or so. So what might a civilization that is a million years more advanced than our own look like?

Todd