In Adrian Tchaikovsky’s The Doors of Eden, the multiverse is filled with parallel Earths where evolution takes different twists and turns.

The forks in the road and the paths species take vary from Earth to Earth, seeding sentience in a wide variety of organisms. In one, giant mollusks “understand and communicate profound truths about the nature of existence.” In another, a creature twice the size of the average human with traits of fish, salamander, and slug creates a permanent ice age and must upload its citizens to supercomputers to survive. Toddler-sized rats pave the planet with Industrial Age warrens in a different Earth. And in still another version of our planet, giant immortal spacefaring trilobites establish themselves at the top of the evolutionary heap for all eternity.

Tchaikovsky’s characters learn about the existence of other Earths because the boundaries between them have sundered, necessitating urgent action. The challenge is no single species has the smarts or technology to fix the problem by itself. Thus they need to create an all-star team of the best and brightest among rats, trilobites, humans, and more if any their worlds hopes to continue.

While mankind’s dominance of Earth has often been mythologized as inevitable, The Doors of Eden presents a countervailing narrative, one that elevates chance as the most important factor in our species’ success.

“One of the big things you run into in studies of evolution is this assumption that we are what it was all aimed towards when, of course, we’re only one rung of the ladder that’s going to run a long way beyond us,” Tchaikovsky says. “If the conditions had been slightly different, we would have been very different. … How other sentient races might have developed from a completely different starting point was very much the point of the book, to be honest. I needed to find a plot that humans could get involved in that would showcase all of those different earths.”