How microbes could beat humans in the race to connect with alien species

Are we alone in the universe? The famous SETI (Search for Extraterrestrial Intelligence) program has been trying to answer this question since 1959. American astronomer Carl Sagan, and many others, believed that other human-like civilizations must exist, and that we could communicate with them. But skeptics are not convinced, arguing the lack of evidence for such civilizations suggests they are exceedingly rare. But if other human-like civilizations are unlikely to exist, could there exist othe