The two discoveries that brought a revolution in early man's life are:
1) Agriculture - It helped the early man to produce its own food. this innovation made possible new flux of innovations and ideas the husbandry and domestication of all modern cattle and pets (except dogs), the formation of soldiers and wars, the money, the origin of religion, writing and all the very basis of modern life. Developing all these new outcomes would be impossible without the cooperation and organized structure of agricultural societies.
2) Language and paintings - Language helps them to communicate with each other and painting which they did at that time helped Historians today to know about their life, language, etc.
When you state or set something forth in words, you have expressed yourself.
Any time cultures interact (example: immigration) they impact each other and cause culture change. Ideas and cultural concepts are constantly spreading and moving and changing.
