Will humanity age and die like everything else, like the whole ever-dispersing universe itself? As they modernize, birthrates in 80+ countries have fallen below the replacement minimum of 2.1 births/woman. With India, South Africa, Mexico... crossing soon, will our species follow fast-aging Japan, whose median age, at current birthrate, could top 60 by 2100? Enter our "demographic fate" hypothesis: does high median age conclude the natural life cycle of all intelligent species in the universe? Do hi-tech species bloom and fade like wildflowers in the cosmic desert, inexorably, being just brainier wild nature? Youthful accidents aside, all civilizations out there may grow old and die like grandpa, naturally and serenely:

-- Freed-by-machines sentient beings adapt to a work-lite leisured life. Kids, once vital for old-age survival, become just another hobby due to computers, robots and the welfare state. -- As their free hearts enjoy competing hobbies (booze, research, selfie, activism...), responsible folks won't bear/order enough babies to sustain their kind. Without immigrants from other worlds, population falls as median age soars. -- The aged majority happily vote not to buy collectively plastic-womb-born state-raised new citizens. The tax jar is for me down here, not for an "our species" abstraction. Absent survival risks, the old also reject space conquests. -- A median-age-72 tiny population, genetically less diverse and full of senile half-present TV/VR/pot fans, will face Murphy's law: whatever can go wrong will... Or the last ones just die out boringly, surrounded by robots. Empirically observed in mankind - the only real-world civilization we can study, is the aging & atrophy of robot-freed societies so far the best-supported explanation for ET's no-show? Unless they're immortal, all alien societies should have a measurable median age. Even if only 1 existed for 10 galaxies, there would still be around 20,000,000,000 civilizations alive within our (200 billion stars per galaxy) x (200 billion galaxies) observable universe? A smart species fades here, another pops up in a nearby galaxy... yet another day in infinity. No good, bad, or purpose to it: it's all wild nature.