If people are endowed with a "number instinct" similar to the "language instinct" — as recent research suggests — then why can't everyone do math? In The Math Gene, mathematician and popular writer Keith Devlin attacks both sides of this question. Devlin offers a breathtakingly new theory of language development that describes how language evolved in two stages and how its main purpose was not communication. Devlin goes on to show that the ability to think mathematically arose out of the same symbol-manipulating ability that was so crucial to the very first emergence of true language. Why, then, can't we do math as well as we speak? The answer, says Devlin, is that we can and do — we just don't recognize when we're using mathematical reasoning.