Later, when living plants appeared, winter and summer created rhythms of growth and decay. In this world evolved ever-changing species of creatures, themselves kept alive by the rhythmic beating of their hearts, the rhythmic breathing of their lungs, the rhythmic swimming, running, or flying of their bodies.

Long before man appeared, many of these animals deliberately danced, as apes, birds, and other creatures still dance. Their dance was prompted by the rhythms of life that pulsed through their bodies and through the universe. Man's first dances probably began in the same way. Many dances of tribal societies still in existence today are said to be identical to those of birds and apes.

Human dancing, therefore, is as old as the first man who expressed his feelings of joy or fear by rhythmically repeated steps or leaps or gestures, perhaps 25,000 years ago. Dancing may well be the oldest of all the arts, and it is an art that needs no instrument other than the dancer's body. Music came later. Originally, stamping feet and clapping hands supplied all the "music" and rhythm needed for the dance.

Dance and music-indeed all the arts-depend on rhythm, as the earliest artists realized. We can see this in the rhythmic pattern of a bushman's woven basket, in the rhythmic repetition of phrases in a native poem or story, in the rhythmically repeated notes of a primitive song. We see rhythm most clearly in the dance - the art of movement whether in the simple leap of the savage or the sophisticated pirouettes of the ballet dancer.

Dancing is worldwide, but throughout the world dances differ. In one land only men dance, in another, only women. Elsewhere, men and women dance together in couples. The dance may be quick or slow, gay or solemn. The reason why so many dances have grown up in different parts of the world lies partly in the dancers' environment: the natural surroundings in which they live. Compare the life of a dweller in a mountain village with the life of a farmer in the valley below. The mountain dweller lives perhaps among hills too steep, too rugged, and too stony for crops to grow in; yet hills that support sheep, goats, or cattle nimble-footed enough to scramble for scattered tufts of grass among the rocks. To survive here the hillman must be a hunter or herdsman, walking many miles a day over the roughest country, his eyes raised to the hill slopes ahead. He develops an alert, springing step, walks with his weight on his toes.

The plainsman lives often on a flat expanse of rich soil where crops grow abundantly. His whole life may be devoted to tending the same few fertile acres, his eyes cast down to the earth beneath his feet as he plows, sows, harrows, or reaps. The plainsman develops a slow, heavy tread, walks with his weight on his whole foot.