Where Good Ideas Come From

by Steven Johnson

The water flea Daphnia lives in most freshwater ponds and swamps. Its spasmodic movements in the water are responsible for the “flea” description, but in reality Daphnia are tiny crustaceans, no more than a few millimeters long. Under normal conditions, Daphnia reproduce asexually, with females producing a brood of identical copies of themselves in a tiny pouch. In this mode, the Daphnia community is composed entirely of females. This reproductive strategy proves to be stunningly successful: in warm summer months, Daphnia will often be one of the most abundant organisms in a pond ecosystem. But when conditions get tough, when droughts or other ecological disturbances happen, or when winter rolls in, the water fleas make a remarkable transformation: they start producing males and switch to reproducing sexually. In part, this switch is attributable to the sturdier eggs produced by sexual reproduction, which are more capable of surviving the long months of winter. But scientists believe that the sudden adoption of sex is also a kind of biological innovation strategy: in challenging times, an organism needs new ideas to meet those new challenges. Reproducing asexually makes perfect sense during prosperous periods: if life is good, keep doing what you’re doing. Don’t mess with success by introducing new genetic combinations. But when the world gets more challenging—scarce resources, predators, parasites—you need to innovate. And the quickest path to innovation lies in making no...