With at least a hundred billion galaxies in the universe, it seems reasonable to hope that there may be life outside our planet. But our existence is possibly a result of a unique set of circumstances, each of which is highly improbable, and together, even more so.

For starters, the timing of our solar system’s birth in the history of galaxies was fortuitous, as is our precise location in the Milky Way. Furthermore, several features of our planet are so rare and finely balanced that the conditions that sparked the evolution of life here seems irreproducible. Perhaps most unlikely of all was the development of our highly intelligent species from the primordial soup that is supposed to have somehow sparked life.

These unusual circumstances are humbling. But because we don’t handle extremely small numbers very well, they are also hard to grasp. Hopefully, the graphic below will help you better grasp the chain of improbable coincides that led to our existence.