Put yourself in these tourists' position. You are walking an icy mountain path in the Alps in Europe. Suddenly you spot a body on the ground,face downward and stuck to the ice. You think someone may have been murdered or in an accident. So you rush back and call the police. The police,however,quickly realize that this body is different from others they've found on the mountain. For one thing,it is mostly undamaged. For another,its skin is dried out,like a mummy's. And with it is a knife with a small stone knife. The body turned out to be much older than the tourists could have guessed. When specialists had a chance to examine it,they discovered it had been there for about five thousand years! How could a body stay preserved for all this time?Two things probably helped. First,the place where the man died was somewhat sheltered,so animals couldn't get at it. Then he was quickly covered by falling snow. Wind blowing through the snow probably "freezedried" his body,removing all  _ from it. Objects found with the body told something about the Iceman's life. He wore a thick fur overcoat and trousers. He clearly had been hunting,for he carried arrows,and animal bones were nearby. He also had a grass cushion for sitting or sleeping on. Perhaps he was exhausted when he lay down for the last time. The body was found in 1991,when some of the ice on the mountain melted. Searching for the cause of the Iceman's death,scientists put the body back into cold conditions and hoped... In this passage the word "moisture" means  _  .
skin nutrition water heat