Nancy Kuh, age 12, of San Francisco, California, for her question:

How did the hippopotamus get his name?

This charming character has the sort of ugliness that makes him handsome. His bulky size inspires awe and his enormous mouth is rather fearsome. However, his gentle nature moderates our reactions and we end by respecting him. Our remote ancestors must have had these same feelings for him. They knew him and named him, for he shared their ancient rivers.     

The hippo part of his name comes from an ancient word for the noble horse, a large animal greatly revered in those early days of human history. "Potamus" was an olden word for river. It was added to distinguish the big fellow from the real horse and perhaps at the same time to put him in his proper place. The term "Eohippus" means the "dawn horse" and scientists coined it to name the little horsey ancestors who lived here, SO million years ago. But the name hippopotamus, "horse of the river", is several thousand years older than the Age of Science.