What would happen if Humanity discovered a primitive civilization on another planet?

Right now, I'd bet we couldn't resist trying to talk to them...  If it was in the future, with a slightly more mature Mankind, we may treat them like they do on Star Trek- and study them while remaining out of sight.  

We would probably eat them

How primitive? By some scales of measurement, WE are still primitive. Whales and dolphins on Earth may be more advanced than we are since they have had world wide communications systems for millions of years.

We have made huge efforts to keep the Moon and Mars pristine. We've failed on the Moon. It has tardigrades that probably came from our vehicles or us. We've probably failed with Mars as well. Technology may not be the best standard of measurement for how "civilized" a group of organisms is. 

Yes, we MIGHT try to communicate with them UNLESS there is a noninterference directive like in Star Trek. Inevitably, someone will violate that directive. 

We are a toxic species. The Solar System may have been quarantined in 1948, or much earlier, that hasn't stopped the 2 or 3% of UFO sightings that are never resolved  and continue to happen. Watch the First Contact series on the  Science channel. The season finale is next Thursday. It's probably on the Discovery channel too. 

Microbes can destroy human civilizations. 


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We would not "leave them alone" judging by history and the time and expense to get to that planet.

We would think we have learned our lessons from our contact with the American INDIANS.

Nothing. They would be too far away.

Nothing. After a few weeks of media sensationalism, people would go back to the business of trying to survive. The discovery would only be useful for trivia nights.

Communication would be absurd seeing it takes years for a simple greeting to be exchanged. Travel to the planet is physically implausible. Except for professional biologists, I don't see why anyone would be the least bit interested in the discovery.

What a great opportunity to convert them to Christianity. Wouldn't they make fine 7th Day Adventists/ Jehovah's Witnesses/ Lutherans/ Presbyterians/ Catholics? And think of all the natural resources we could exploit! Oh boy!

What happened when we discovered the Indians in America.

This is to prove that imagination has no bound, it would go and on till become tired of asking.

Well, humans have a hard time living in harmony with our own kind here on earth, so go figure. The novelty would wear off so hard to say what long term effects would happen.
At least take comfort in knowing it would take a great many centuries for any interaction with any ET here in our own galaxy.