Reply #101: In fact, humans evolved to have one child every 4 or 5 years

[Piltdown13]

...not every single year. Sure, it's physically possible for some women to have one a year for many years, but that's not what happened during the vast majority of our evolutionary history (as evidenced by the health problems caused by so many pregnancies). Before the advent of agriculture/more or less sedentary life (i.e., back when we were all hunter-gatherers), each offspring would be nursed for 3-4 years, which would suppress ovulation to the extent that generally, the woman wouldn't get pregnant again until the previous kid was weaned (or about to be). Of course, the interval between successive births would be less if a child died during infancy.