A major piece of inspiration was this article in Scientific American by David Biello, about how the human era (the Anthropocene) might be remembered in the geological record.
This set me thinking about the evolution and extinction of species on a geological timescale, and how humans might be a flash-in-the-pan. I drafted the poem without knowing how to integrate it with data, but when I saw that the block-like stanzas looked like geological strata, I decided to bury it in the fossil record.
There are four stanzas, equating to four eras, going 1 billion years back in time. The problem was that the eras are different sizes, with the older ones being much longer. I tried laying out the poem on a vertical timeline and it was ridiculously long; there was a good chance people would just stop scrolling before they reached the end!
To compress the timescale more at the end I tried using logarithmic scales. I experimented with different bases (having the opposite problem with base 10, that made the end segment wafer thin), and it was base-2 that gave the most evenly sized layers. Base-2 is used extensively in genomics and computer science, so using it to format a digital poem on natural history pleases me greatly!