I want to open with a quote that appears early in Marco Iacoboni's new book, Mirroring People: The New Science of How We Connect with Others: "Some years ago [it was] suggested that the discovery of mirror neurons promised to do for neuroscience what the discovery of DNA did for biology. That's an extraordinarily bold statement, because essentially everything in biology comes back to DNA. Decades in the future, will everything in neuroscience be seen as coming back to mirror neurons?" Considering recent discoveries about the relationship between mirror neurons and language, mirror neurons and emotional states, mirror neurons and social practices, this "bold statement" is not strong enough. We must add more force to it: What the discovery of DNA did for biology is what the discovery of mirror neurons will do for all of culture.

But let's go back before we leap forward. Mirror neurons are neurons in the brain that fire when a primate sees another primate perform an action. Meaning, the action (grabbing a cup, caressing a nipple, making a face) is not simply seen, it is also experienced within the head of the perceiver. Furthermore, it is experienced as if the primate had committed the action him/herself. Ultimately, learning, talking, acting are the products of direct, even crude, imitation, or, to use the language of Iacoboni, simulation. We not only learn from others, we are others.

"We [even] have empathy for fictional characters—we know how they are feeling—because we literally experience the same feelings ourselves. And when we watch movie stars kiss on-screen? Some of the cells firing in our brain are the same ones that fire when we kiss our lovers," writes Iacoboni, a neuroscientist who currently works at UCLA but 15 years ago lived in Parma, Italy. Here, a team of Parman scientists, led by Iacoboni's friend Giacomo Rizzolatti, discovered mirror neurons by accident. One of the stories about how it happened goes like this: 20 years ago, a macaque, a species of monkey, sat quietly on a chair as a scientist, Vittorio Gallese, prepared a new assignment. The macaque had electrodes connected to its brain and small eyes that followed the scientist's doings in the lab. When the scientist reached for something (he doesn't recall what it was exactly) on a table nearby, suddenly there was much excitement on the computer. Gallese was confused because the situation and the information did not match: The computer noise indicated that the monkey was grasping something, but in reality it was doing nothing but looking at someone grasping something. The scientists at the University of Parma eventually solved a mystery that would not only change the field of neuroscience but also our understanding of culture.

A quick word on the book (writing style, level of difficulty, and so on) before we leap into things. The cognitive linguist George Lakoff offers this blurb on the back cover: "A superb introduction to one of the great discoveries of contemporary science: We come wired for empathy and cooperation, and evolution has equipped us to care, not just compete." The critic in me can hardly improve on this. The book is a clear and excellent introduction to a very complex science. That's that. And now for the leap.

In chapter two, "Simon Says," Iacoboni names Susan Blackmore, a psychologist and author of The Meme Machine, as a thinker who, outside of neuroscience, recognized the centrality of mimicry in the constitution of the human self. Another mentioned thinker is Andrew Meltzoff, a child-development expert who maintains that babies begin imitating before their first hour of life is up. As for the word "simulation," Iacoboni borrowed it from Alvin Goldman, a philosopher. But the person whose work really deserves credit and attention, the 19th-century French sociologist Gabriel Tarde, is absent from this book.

Why is Tarde all of a sudden relevant? Read this passage from his masterpiece The Laws of Imitation: "All resemblances of social origin in society are the direct or indirect fruit of the various forms of imitation— custom-imitation or fashion-imitation, sympathy-imitation or obedience-imitation, precept-imitation or education-imitation; naive imitation, deliberate imitation, etc." The only piece missing from this picture is a mirror neuron.

Imitation (or simulation, or mimicry) is the foundation of social life, and the production and structuring of social life is the business of politics. Therefore, it's not surprising that one of most revealing experiments in the book, which happened during the Bush/Kerry presidential race in 2004, determined that the mirror neurons of people who are concerned about politics (political junkies, as Iacoboni calls them) become very active when they are shown a political figure and silent when shown a nonpolitical figure. The mirror neurons of people who were not interested in politics, however, exhibited little or no activity when they were shown both political and nonpolitical figures. The results of this experiment suggested that an interest in politics is not something learned or developed but is there from the very start. Mirror neurons only fire when they are interested in something that you are seeing. No interest in politics, no activity in that region of the brain.

Because we entered, by way of biology, the subject of politics, we are now at the threshold of a biology of the arts. As Iacoboni points out again and again, mirror neurons are connected directly with empathy. And empathy is connected with our sense of morality. When someone is in pain, we also feel their pain. When we see someone in love, we feel their love as if we were in love. When someone speaks, we don't really listen to them but speak as they speak. So, if we want to locate the source and function of the arts, we must go to these neurons and nowhere else. Indeed, the French novelist Marcel Proust once wrote that art had the purpose of linking one person to the soul of another. This function, this necessity, has its origin in the mirror neuron.