As well as looking for alien life in space, should we also be looking in time?

How do we know we are the first (indigenous or not) intelligent beings to inhabit this solar system? If there had been a prior civilisation on Earth we would probably have found some evidence of it, but if there had been one on Mars of Venus how would we know?

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"I worry that, especially as the Millennium edges nearer, pseudo-science and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive." - Carl Sagan, 1995

The more we can visit these planets (and the large moons in the solar system as well), the more we will look for any signs of life, current (unlikely in most cases, extremelyu unlikely that there is intelligent life) and past.
We don't know that we are the first (and as always, it will be impossible to proof that we are the first), but we have until now no serious evidence at all that there is or has been intelligent life in the solar system, and we have evidence that life as we know it would have had a hard time to develop at most of the planets and moons.
But for a while after we start to regularly visit planets, there will be countless searches for past life on those, and we will be much better able to give an answer then.

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Knowledge is a curse, but ignorance is worse

I agree, we need to go to other planets and do a great deal more investigation before we reach any conclusion about the possibility of life having been in our solar system in the past.

However, some seem to sort of "put the proverbial cart before the horse" in this area. For example, Richard Hoagland uses questionable (very questionable) images that he says are evidence of artificial structures indicating past civilizations. This just isn't going to "cut it". Speculation about past life in our solar system is one thing, evidence of said, past life, is quite another thing.

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An open mind is like an open window...without a good screen you'll get all sorts of weird bugs!

I agree that Richard Hoagland is a woowoo. Presumably any structures left behind on Mars when it was habitable would've been buried/destroyed a very long time ago.

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"I worry that, especially as the Millennium edges nearer, pseudo-science and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive." - Carl Sagan, 1995

Yes well things do get un burried naturally, thats how a few of the greatest finds in Egypt have happened.

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-The Wolf
http://www.ryanmercer.com

True.

Of course, Mars has lots of dust and Venus a corrosive atmosphere - over the timescale we'd be talking about they would take care of anything exposed.

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"I worry that, especially as the Millennium edges nearer, pseudo-science and superstition will seem year by year more tempting, the siren song of unreason more sonorous and attractive." - Carl Sagan, 1995