An ETI's "bugs" most likely won't affect us, nor ours them. Look how few diseases are trans-species here on Earth, where everything at least uses the same basic systems (DNA, proteins, etc.).

Odds are that life from another planet will have basic differences from Earth life that make cross-species contamination impossible.

I recognize, though, that "unlikely" is not the same as "impossible" and chance might deal us the Ace of Spades, and we get invaded by displaced ETIs looking for a new home, who have a devastating disease they are adapted to, but that wipes us out.

I just wouldn't bet on it.

Mebbe so - wish there was an emoticon that had its tongue firmly in cheek, I might have used it.

As far as the Aztec comment, I was thinking we would be at a definite disadvantage on all fronts. Earthlings overall seem fairly primitive on technological, social, economic, mythical/religious fronts. Aliens might be benevolent, or might not. No more than to Cortez, the fate of our civilization might not amount to a hill of beans to them.

Reading the pieces within the 'Don't talk to strangers' link they do point out that societies can be altered in unexpected ways by the emotional and conceptual alterations brought on by contact. The Japanese society was centered around them being special. Arrival of an army and fleet far superior militarily to their own was quite a shock. It shattered their political, military, even their religious, systems and brought down a dynasty. The changes to the Japanese society set up the invasion of China and Japanese involvement in WW2.

Arrival of vastly superior aliens would drastically change the context of all human existence. US standing as superpower, and the secondary and tertiary standing of all other nations, puts things in a completely different light. Presently the US is, within the real and profound limits of any power, the final word.

What would the existence of aliens do to religious belief. Or the idea that humans are special.

Like "Calvin and Hobbes" said, the surest sign that there's intelligent life in the universe is that they haven't tried to contact us.

I'm sure that Europe and China would be purely delighted to hear that -not. America is not the pre-eminent power in the 21st Century. Mighty? Yes. Final word? No. But that's politics.

I think that - returning to the subject of first contact - aliens who are xenophobic, perhaps rabidly so, arn't going to bother doing a Hollywood Invasion. Why bother? Half a dozen Dinosaur Killers delivered from the edge of the system, at about 0.01c will do the job very nicely.

Leigh, while the gist of your post has merit, I'd like to point out that Europe is NOT a country.... though they're sure (finally) starting to cooperate like one.