In presenting his twelve-month capsule of the history of the cosmos, Carl Sagan emphasized how new we are in the universe. “The world is very old, and human beings are very young,” he wrote. But I read his calendar differently.
Sagan included “The Cosmic Calendar” in The Dragons of Eden in 1977. The first voyage to Mars had lifted off two years before. NASA, with the help of Sagan himself, began listening for and sending messages to intelligent beings elsewhere. Sagan wanted us to appreciate our amazing intelligence, but at the same time he believed we were not the only ones in the universe who had it. The Cosmic Calendar helped him show that because it took eons to produce human civilization, the eons might have led to similar results elsewhere.
On his calendar (dates here are from the Wikipedia version), the Big Bang takes place on January 1, the Milky Way takes shape around March 11, our Sun appears on September 2 with its planets soon after. Life begins on September 21. All of October is blank because there were no outstanding organic firsts, just the persistence of simple bacteria and their cousins. In November, those single cells developed nuclei and become more complex and energetic, leading to the first multi-celled organisms in early December. From then on, the variety of life emerged swiftly: fish and land plants in mid-month, dinosaurs at Christmas, then birds and flowers, and humans in the last hours of New Year’s Eve.
What I take away from such a sequence is not how recent we are but how ancient. We come from a chain of living things that is so long it reaches back to September 21, through more than a quarter of the duration of the entire universe. As living things, we are not newcomers to the universe. We are long-time participants, old-timers. We are fully part of the gradualness of the cosmic process, not just because our atoms are star-stuff but because our cells have their own ancient history. What is new in us, with our nearly-New-Year’s brains, is that we are aware of it. But our living spark is as old as planets.