• the_strange@feddit.org
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      14 小时前

      The growth (or in this case decline) is exponential. 1.08 is bad, 0.80 is terrifying. 1.08 is roughly half of the fertility needed for a stable population (about 2.1 children per woman). This means that per generation your population shrinks by half its size. 0.8 is another 25% lower. At an exponential rate these differences add up fast. The first one gives you (roughly) one child per 8 great grandparents. The other one needs 18. So over 3 generations the population shrinks by another factor of more than a half.