Evolutionary biologists get used to the idea that all of human history, and all of our existence as a species, is just a tiny slice of recent time in the cosmic scheme of things. An infinitessimal blink of an eye. Before humankind, there were vast amounts of time where the earth was dominated by other animals like dinosaurs. And those millions of years are themselves miniscule compared to the time before when all life on earth was marine. And large multicellular life is itself a recent late-comer, compared to the eons and eons when all life was microbial. And even that is recent, compared to the age of the universe.
Well, kinda. One thing that’s struck me since we got a good handle of the age of the universe is that earth, in the cosmic scheme of things, is a lot older than I expected. The universe is 13.8 billion years old, and the earth 4.5 billion years old. That means the earth is roughly one third the age of the universe—pretty darn old. And what’s more, the earliest life on earth appears to date to around 3.5 billion years ago. That means life on earth is one quarter the age of the universe. Considering it all started with a bunch of hydrogen and helium, that seems like a pretty early start.
Just out of curiosity, to get a better sense of when various things happened in the cosmic scheme of things, I made a timeline. And to make things clearer when there’s a lot going on at one end of a scale I did what I usually do—use a log scale. I added a bunch of reference points that made sense to me (hence the Ameri-centrism) until I got a decent spread of events along the line. The dates can be very approximate, and are mostly taken off wikipedia, so take them with a grain of salt. I ended up with the image shown here.
What really surprised me here was how much space, on a log scale, humans take up. The last third is recorded human history. The middle third is human prehistory—the realm of physical anthropologists and archaeologists. This first third has all the big astronomical and pre-human biological events.
It’s kind of cool to have a single graph that include all of time, from the beginning of everything to recent historical events. Searching the internet just now, I’m not surprised to find that people have made things like this before. Still, I like my version better.