Like many novel technologies in this age of TED Talks and Silicon Valley triumphalism, synthetic biology—synbio for short—floats on a sea of hype. One of its founding scientists, Boston University biomedical engineer James Collins, has called it "genetic engineering on steroids." Whereas garden-variety genetic engineers busy themselves moving genes from one organism into another—to create tomatoes that don't bruise easily, for example—synthetic biologists generate new DNA sequences the way programmers write code, creating new life-forms. It may sound like science fiction, but synbio companies have already performed modest miracles.