There are organisms at the bottom of the ocean around volcano vents that don't need oxygen. It's thought they are among the oldest, most primitive forms of life.Yes. IIRC, our planet didn't originally have oxygen. Oxygen was by-product of evolving life. Could this be a means to detect life? I don't know.Finding "life" and finding a civilization equal to our own are two widely different things. Additionally, if a star is only 40 light years away, it's probably about the same age as our own solar system which means, given our system is "average", wouldn't have anyone capable of interstellar travel. Heck, it'd take 80 years just to send a message out at the speed of light and see it returned.I think the majority of us would like to find out that we are not alone before we die.
Agree I think the op meant life
Learned something new today, I should have studied more, so oxygen is a byproduct of evolution?
Going to Google it
How did life begin on Earth? - Quora
Were the very initial forms of life, the common ancestors of both aerobic and anaerobic organisms, aerobic or anaerobic themselves? - Quora
Why do we not have higher anaerobic life forms on earth? - Quora