Henry Miles, age 10, of Peoria Illinois, for his question:

Why did all the mammoths die?

These giant animals were related to our jumbo sized elephants. Some of them were bigger than elephants and had shaggy coats. They lived on earth for millions of years, along with other elephant cousins. But the last of the mammoths departed with the ice ages that came during the last million years. We know this because scientists have dated the rocks in which they left their huge fossilized bones and tusks. What's more, bodies of mammoths have been found in the Arctic, where they were frozen and preserved in ice age glaciers.

We cannot explain why all the mammoths died out, but perhaps the changing world climate had something to do with it. The saber toothed tiger, giant sloths and bears and many other creatures also became extinct about the same time. The four ices of the past million years were separated by rather long warm periods. Perhaps the mammoths were wiped out by the cold or the warm spells or maybe they failed to adjust to the extreme changes in the climate.