I wonder how much of this was the result of food scraps from US bases? I've been told a number of Korean dishes use ingredients that were begged from American GIs during and after the war. Things like hotdogs and american cheese that then got used creatively. I know other species will see a huge birth spike from discovered food sources. But I don't know if human's are smart enough, or have expensive enough pregnancies and child rearing to avoid this potential trap.

It was the period of the most rapid population growth globally. And the period during which antibiotics became widely available.