What explains the incredible variety of life on Earth? It seems obvious. Evolution, of course! But perhaps not the evolution most people grew up with.

Some ecologists say the theory needs an update. They’ve proposed a new dynamic driving the emergence of new species, one that doesn’t involve adaptations or survival of the fittest.

Give evolution enough time and space, they say, and new species can just happen. Speciation might not only be an evolutionary consequence of fitness differences and natural selection, but a property intrinsic to evolution, just as all matter has gravity.

“Our work shows that evolution wants to be diverse,” said Yaneer Bar-Yam, president of the New England Complex Systems Institute. “It’s enough for organisms to be spread out in space and time.”