Babylonians and Maya already used a sign to mark an empty place. But it was the Indian astronomer Brahmagupta who, in 628, set out rules for calculating with zero as a number in its own right, adding and subtracting it, alongside negative numbers. That knowledge then traveled through the Arab world before reaching Europe.
Around 2300 BCE, Enheduanna, daughter of King Sargon of Akkad, became high priestess of the Moon god at Ur. She composed hymns to the goddess Inanna and put her name to them. She is the oldest person identified as the author of a literary work, about 1,500 years before Homer.
Squeeze Earth's 4.5 billion years into a single 24-hour day. Homo sapiens shows up around 11:59:54 p.m., roughly six seconds before midnight. All of written history, from Sumerian tablets to today, fits into the final tenth of a second. A cosmic blink.