For over 14,000 years Native Americans must have looked out at the ocean and asked “are we alone on the planet? Is there intelligent life on other continents? We must be alone; we’ve been looking at the ocean for 14,000 years and no intelligent life has ever come our way. We are alone on the planet”
Then one day in 1492, they were invaded by another intelligent life form known as the white man.
What does this tell us about life on other planets?
If it took 14,000 years to be visited by intelligent life that Native Americans shared a common ancestor with only 41,000 years ago, then this suggests it takes 34% of the time since two populations diverged for one of the populations to find the other.
Thus if our galaxy is 13.6 billion years old, any other intelligent life will share a common cosmic non-living source with us about 13.6 billion years ago. Thus it should take them 0.34(13.6 billion) = 4.6 billion years to find us. Life has only been on Earth for 3.7 billion years, so I expect aliens to discover us in about 900 million years.