Just to expand a bit on a point I made briefly in my post #5 above:
Arguably there is an evolutionary 'singularity' whenever an intelligent species understands the processes by which it has evolved and acquires the ability to control them. Any species capable of interstellar travel and exploration must have reached this stage.
The control of evolutionary processes might take several forms, such as selective reproduction (eugenics), genetic engineering, or biochemical controls (as in Aldous Huxley's
Brave New World)
. The
direction in which such methods might be taken would presumably vary according to the values and beliefs of the society in question (or its rulers!) Plausibly, some characteristics would be almost universally favored, such as health, intelligence and good looks (according to the standards of the species), while others such as illness. stupidity, and deformity, would be eliminated as far as possible. (Of course, 'eugenics' is now very out of fashion,, at least in western countries, but more in reaction against the methods previously used than the ultimate aims. If prospective parents could safely boost the health, intelligence and appearance of their children just by taking a pill, how many would reject the option? )
But beyond these basics, the aims might vary considerably. An internally uniform and and conformist but outwardly xenophobic society (think of your own examples) might take measures to reinforce and intensify these tendencies.
A very inegalitarian society might be taken in the direction favored by its ruling class, with even greater inequality (think of the Eloi and Morlocks of
The Time Machine. )
If the biology of the species is such that the greatest of all motives is
reproduction, we might expect it to give priority to increasing fertility. Such species would probably be the ones most interested in colonising other planets.
Another possibility is that beyond a certain point of development a society would devote itself to the pursuit of pure pleasure. If the society has obtained complete control of its environment, eliminated the need for work, and discovered everything of interest that is to be discovered about nature, what would be left?
If the last of these possibilities is the most common end-point of evolution, we may have another solution to the Fermi Paradox. Why would a species waste time exploring other planets if it already knows everything worth knowing, and has the opportunity to luxuriate in endless ecstasy?