Scientists believe that people 'dressed up' long before they made a habit of wearing clothes. Primitive man dressed himself in feathers and ornaments, or painted his body and wrapped himself in animal skins. It was probably some time before man discovered that the decorations kept him warm and protected him from-various injuries. Even today, millions of people who wear little clothing use ornaments and decorations. When primitive people began to wear clothing regularly, they had to make it from the materials at hand, In cold regions, they often used the skins of fur-bearing animals as protection against the cold. In warmer regions of the world, the people dressed themselves in clothing made from leaves, tree bark and woven grasses. Some people scraped the hair from animal skins to make soft leather for their clothes. Linen was the first woven material from which clothes were made. From very early times, men have known how to make flax into fine linen. In fact, over four thousand years ago, Egyptians grew flax along the banks of the Nile River. They learned how to make threads from the fiber of the flax plant, and the linen that the ancient Egyptians wore was softer, finer linen than the linen today. However, only the very rich Egyptians could afford this fine linen. The poor people of ancient Egypt wore very coarse linen or animal skins, and most of them owned only one garment apiece. Egyptian and Jewish priests, who lived in warm lands, wore fine linen clothing at religious festivals. The Egyptians wound their mummies in bands of linen before placing them in the tomb. Fine linen was also worn by the wealthy Greeks of ancient times. And, during the Middle Ages, most of the people in Europe wore linen. Wool was probably the second woven material to be' for clothes, because there are many kinds of sheep that can live in many different climates, and because sheep are easy to raise they have been raised in many parts of the world for their meat and their soft, warm wool. We do not know when people first thought of cutting off the sheep's wool and spinning it into yarn. However, we do know that, very early in history, rich and poor people alike were wearing wool clothes. Amusingly, sheep's wool wasn't the only wool used by early man. The desert people made clothing from camel' s hair the people of Asia minor used the fleece of the angora goat, the people of northern India and Tibet wove the fleece of the cashmere goat into soft, warm clothing and the South American Indians made clothes from the wood of the Hama, their beast of burden. According to the passage, why primitive people 'dressed up' ?