Janet Dance, age 10, of Shreveport, Louisiana, for her question:

Is it true that the horse once had five toes?

The horse is a hoofed animal and each member of his family, wild or tame, is allowed one hoof on each of his four feet. No horse of modern times trots along on five toes. However, the remote ancestors of our big, beautiful horses were bunny sized creatures with toes on their feet.

Horses have been horses, just as they are today, for the past million years or so. But their ancestors, who arrived on earth some 55 million years ago, were not very horsy. Children of course take after their parents, but nature rules that each new creature also must be a bit different from either parent and also different from every ancestor that came before. In 55 million years the generations of horses have had time to make a great many changes. And they certainly have made the best of their chances to improve themselves.

The earliest horse we have so far been able to piece together from the fossils and other evidence of the earth's past was the size of a leggy jackrabbit and like a jackrabbit he munched the green grasses. He ran and trotted around on padded toes with sturdy nails four toes on each front foot and three toes on each hind foot. His chewing teeth were soft. This was all right because his world was carpeted with the softest of greenery. He was a handsome little fellow with a flowing tail and mane and a gracefully arched neck and back. Many scientists believe that an even more remote horse ancestor did indeed have five toes on each foot.

Through the ages, nature changes the scenery and the climate. The balmy early days became cooler and tough prairier grasses replaced the tender old greenery. These changes were challenges and all the living, animals had to face them and solve them or perish. Many herds of early horses starved because their teeth were too soft to chew the tough new greenery. But here and there a few little horses happened to have tougher teeth and they survived. Most of their children inherited these tougher teeth. In time, the whole horse population had stronger teeth. But several other bigger, fleet footed meat eaters threatened meantime the wolf population grew bigger and the grass eating horses.

These enemies also reduced the horse population. The smallest horses were weeded out. The larger survivors tended to have larger children. And the grazing herd learned to be wary, to watch out for hungry meat eaters. The fastest horses could escape their enemies. Through the ages, the descendants of the early horses grew bigger bodies and longer, stronger running legs. They took to standing on one toe on each foot. Over time, this dependable toe developed into a sturdy hoof. Nature tends to scrap unused parts and gradually the remaining toes dwindled to almost nothing.

The strangest part of the age-old horse story is the setting. When Columbus reached the New World, there were no Native American horses. But scientists later found countless fossil remains of horsy ancestors. We now know that the first little horses got their start in North America. Ages ago, some of them strayed across land bridges to the old World and flourished there. Meantime some mysterious tragedy wiped out all the herds that stayed behind in their original homeland.