Roger Leo, age 10, of Staten Island, N.Y., for his question:

WHAT IS THE SMARTEST ANIMAL?

Animal experts tell us that an animal has high intelligence if he learns quickly and tries new experiences as an adult. Rated highest on the intelligence scale by many scientists are the apes and monkeys. The chimpanzee is so smart he can be trained to operate complicated electronic instruments used to guide space vehicles. Dolphins, the most intelligent animal that lives in the water, can be trained to locate and retrieve devices on the ocean floor. What's more, we all know what a fantastic performer he is.

If we were to ask the animals themselves, however, we might get a totally different answer. They might say that their champ in the smarts department was the animal who had survived hunger and cold. Or they might nominate the lowly cockroach, who has adapted to changing environments for countless centuries. "Smart" to animals might mean having healthy children, having a full tummy every day and, most important, not becoming a tummyful to some other animal.