I understand that many women will not have kids or will have only one kid, or that child mortality is involved but still a fertility rate of 2 means that ON AVERAGE every woman will have 2 kids. This means that every woman and man will be replaced, including the children that die young if the rate of 2 lasts (the newborn females will also have on average two kids). So why isn’t a fertility rate of 2 enough to replace the population?
In: 701
Perfect world on 2.0: population of 1000 people, 500 couples, they each have 2 kids on average, next gen is 1000 people. Lather, rinse, repeat.
Real world with 2.0: population of 1000 people, 476 reproductive couples (some homosexual couples, some sterile, some single people, some die before reproducing), 2 kids each, that’s 952 for next generation. Same ratio, there’s now there’s only 453 reproductive couples, 2 kids each that’s 906 next generation. And so on and so on.
Real world with 2.1: 1000, 476 couples, 2.1 kids means 1000 people for next gen.
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