"Oh, come on, Cowboy Bob! What do UFOs have to do with evolution?"
More than you think. Although strange objects in the sky have been reported for many years, the "Flying Saucer Crash at Roswell" in 1947 (near the beginning of the Cold War) stirred the public's attention. This was great for anti-government conspiracy theorists, science fiction stories, the ridiculous pseudoscience of "panspermia" — and Roswell's tourism.
Evolutionists insist that not only did life evolve here (a hypothesis that is consistently dismantled here and in linked articles), but it must have evolved in space. New Agers "channel" various entities, including aliens. The message of these aliens is often that they are more highly evolved, and want to help us evolve into enlightenment.
As for Roswell's "crash"? Not so spectacular, it seems.