Primitive society to survive, you must obtain from the nature, and the prey, and the beasts of prey dealing with natural disasters are toughly, is a kind of physical game.

• 原始社会人类要生存，就必须从自然界获取猎物，要与猛禽野兽打交道，与各种自然灾害进行顽强地抗争，是一种体能的博弈。