Biology class is all about putting living things into categories, based on their differences. And creatures are different because they have different genes. But life wasn’t always like that. In this segment, Steve Strogatz, an applied mathematician at Cornell, tells us about a radical theory that says that way back at the beginning of life, three billion years ago, life was a big commune of gene swapping. Nigel Goldenfeld, one of the scientists who came up with this theory, says that the idea of different species, and consequently Darwinian evolution, simply didn’t apply for the first billion years of life on Earth. Then we follow the thread of an essay by Freeman Dyson called "Our Biotech Future." According to Dyson, the rise of biotechnology means that there will be an explosion of new life forms, that we will start moving genes from one creature to another. So we go to MIT, where Stephen Payne and Reshma Shetty prove Dyson’s point by making stinky bacteria smell nice.