For decades, Dalton Conley tried to answer the big social questions--about why groups hold together, about inequality, and more--through the traditional tools of his first field, sociology. He eventually found that those tools could take him only so far. So he went back to school and got another PhD--in biology. Now, in The Social Genome, Conley explains how the new field he has helped to pioneer, sociogenomics, will upend our world. The key is...