Becoming Housebroken

Shiba Inus have a reputation of becoming housebroken early. Indeed, me and my brothers were housebroken before my brothers left us for their new families at an age of eight weeks, so were my own pups. I have no first hand experience of children, but I always assumed that it would not take that much longer time for humans to become housebroken. A dog's year is about seven human years, so I assumed the ratio would have been about the same (two months - fourteen months). Then I read this article about a human child, housebroken at the "early" age of one-and-a-half years. Well, I guess there are always new things to learn about our world.