Knocking two rocks together can be just as important as sending a man to the moon.

When ancient humans learnt to use stone tools and make fire, it meant the beginning of modern society.

Later discoveries -- bronze, iron, steam, electricity, to name a few -- continued the development of society and shaped history.

So important were these achievements that we often divide human history into time periods named after the latest technology of the time:

The Stone Age, the Bronze Age, the Iron Age and so on.

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