Kathy Klein, age 10, of Tucker, Ga., for her question:

WHEN DID THE SABER TOOTHED TIGER BECOME EXTINCT?

This big cat with nine inch fangs shared the world with our caveman ancestors. But we cannot blame mankind for his extinction. No doubt Mother Nature herself decided that it was time for him to depart from the planet earth. After all, his family had been here for 40 million years. Somehow he survived through the ice ages. But for reasons unknown he became extinct about 12,000 years ago.