Scientists believe that Mars is the way it is as the result of a hugh asteroid strike some billions of years ago when mars was wet and warm with tectonic activity. If Mars had a civilization it would have had to have been there over two billion years ago. The earth didn't have a civilization or intelligent life two billion years ago so why should Mars have had intelligent life and a civilization?
I don't know the source of your data, Cain, but let's look at it.
The last major strike or group of strikes the earth/moon went through (large enough to liquify the surface) was about 3.8 billion years ago (the close of the Hadeon eon and the start of the Archean Eon. Presumably Mars follows about the same timeline, as we are close solar neighbors. The Martian history goes something like this (very tentative, of course):
- Mars crust grows thick enough from loss of the initial heat of formation o stop continental drift: 3.5 bya
- Mars internal heating from radioactivity causes the Tharsis ridge bulge and the resulting volcanoes: 3-2.5 bya.
- the core freezes enough to reduce the magnetic field to nearly zero, with resulting loss of atmosphere: 2.5-2.0 bya.
It would seem, again very tentatively that Mars might have the capability of growing a civilazation if it could have happebned within a billion years. Could it? I don't know.
When water existed in liquid form on Mars it was extremely saline much more so than the earths ocean. This is not conducive to the formation of the more complex life forms that would be necessary for the evolution of intelligent life.
One, I don' know where you may have seen this salt hypothesis, but I think it would be very, very tentative, based on the fact that we've nothing we can subject to analysis here on earth, and secondly because our land sampling data is so sparse. Second, why couldn't life grow up in it? Life lives in he Dead Sea and the Great Salt Lake. Different strokes for different environments, I say.
I feel that this is a tradgedy because if Mars had stayed wet and relatively warm the human race would have had another place to live without the necessity of terraforming. Had Mars stayed warm the only intelligent life to live there would be human colonists.
Again, I find that last to be very speculative.
I don't think I need to say that I feel such a civilization is a long, long shot. I just disagree with your reasoning.