The issue, as correctly emphasized by Carl Sagan, is the probability of the evolution of high intelligence and an electronic civilization on an inhabited world. Once we have life (and almost surely it will be very different from life on Earth), what is the probability of its developing a lineage with high intelligence? On Earth, among millions of lineages of organisms and perhaps 50 billion speciation events, only one led to high intelligence; this makes me believe in its utter improbability.
Ernst MayrIt is curious how often erroneous theories have had a beneficial effect for particular branches of science.
Ernst MayrA species is a reproductive community of populations reproductively isolated from others that occupies a specific niche in nature.
Ernst MayrI had found again and again that the most aberrant population of a species - often having reached species rank, and occasionally classified even as a separate genus - occurred at a peripheral location, indeed usually at the most isolated peripheral location.
Ernst Mayr