How did the cave men discover fire?

Civilization began when man discovered how to make and use fire. Primitives used to keep a perpetual fire going as it was difficult to start a new fire. The first fire was probably started when lightning struck a rotten tree and made it smoulder. Later they learnt to make fire by striking stones together. In Alaska, some tribes still make fire this way. North American Indians rubbed two sticks together to make fire.