Humans and all of our many societies and cultures have historically engaged in unspeakable violence towards each other for reasons which most of the time amount to no more than our inability to accept differing opinions,faith and beliefs.An intelligient lifeform may observe our planet and react the same way many on this planet would react with fright.

This is my opinion on why up to this point in earth history there has been no true contact with other intelligient lifeforms.They more than likely have evolved to
a level appreciation and reverence for all living matter that we unfortunately have yet to reach.

I'm hopeful that an alien civilization would be able to calculate the risk of contact with us as one that would be
of great benefit to us both.