Biologists who study cancer have been borrowing a lot of concepts from evolution in recent years. That’s because the changes that occur inside a tumor bear some striking resemblances to what natural selection does to a population of animals, plants, or bacteria. Evolutionary biologists who study societies–from human tribes to ant colonies–have investigated how cooperation can evolve when cheating can let some individuals get ahead. Now scientists are finding evidence of cooperation and cheating among cancer cells. In my column this week for the New York Timesmy column this week for the New York Times, I look at the social life of cancer–and how we might undermine it to fight the disease.