How do language and ideas propagate through communities? We use computational linguistics to extract social meaning from language to help understand this crucial link between individual cognition and social groups. I'll discuss the way economic, social, and psychological variables are reflected in the language we use to talk about food. I'll introduce the "ketchup theory of innovation" on the crucial role that interdisciplinarity plays in the history of innovation and how it can be discovered via language. Finally I'll show how computational methods can address the mystery of why linguistic innovation changes sharply across people's lifespan.