In The Hitchhiker’s Guide to the Galaxy, Douglas Adams noted that “on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much—the wheel, New York, wars, and so on—whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man—for precisely the same reasons.”

This is an interesting point, and one that’s tackled in great detail in Kevin Laland’s new book, Darwin’s Unfinished Symphony. Other species are indisputably smart; they can learn by example, they can communicate, they can innovate to solve problems, they can use tools, they may even have distinct cultures. But humans are clearly different. Other species don’t listen to Baroque concerti or read classical philosophy hundreds of years after the scores were composed or the treatises written. They just don’t.

A culture of teaching

This difference really bugged Laland. He is loath to say that humans are special because that implies some vast, unbridgeable gulf between us and our closest kin. Laland is an evolutionary biologist, and he doesn’t go for those sorts of claims. He knows that humans evolved from a common ancestor with other primates through natural selection and other such well-defined mechanisms.

Yet a vast, unbridgeable gulf really does, in fact, come between us and our closest kin. Something huge must have happened to explain how and why we alone have built cathedrals and telescopes and banks and submarines and smartphones and particle accelerators. This is not navel gazing; we are special.

So, with Darwin’s Unfinished Symphony, Laland set out to define what that something huge was. He concluded that it was not as dramatic as one of our early ancestors getting repeatedly struck by lightning or bitten by a radioactive spider. Rather, his thesis is that humans alone evolved such a complex culture because humans alone have teachers dedicated to teaching their young. And the reason only we have teachers—people who devote the bulk of their lives to teaching the offspring of strangers not only vital life skills, like how to hunt and fish, but the entire accumulated knowledge of our species over the past few millennia—is because... we have such a complex culture.

Yes, that’s circular. We generated culture, which shaped our evolution to allow us to devise language so we could generate an increasingly complex culture—well, that’s how feedback loops work.

Mimicry vs. learning

Many animals can copy each other’s behaviors, but early humans did it better than other organisms. This allowed those behaviors to stick around in the population for a long time, which in turn allowed for people to tweak and improve each behavior incrementally. This is how innovation generally happens—not in a huge burst of individual inspiration, but in tiny steps made by different people over time. So once our complex culture developed, it became a selective force that drove the evolution of our bodies, brains, and minds. Because once we developed complicated culture, we needed to develop the mechanisms to maintain it.

Teaching allowed for and promoted the evolution of culture by epitomizing a combination of two uniquely human traits: cooperation and language. “What singles out our species,” Laland writes, “is an ability to pool our insights and knowledge, and build on each other’s solutions.” Chimpanzees can teach one another how to get ants out of holes using sticks, but none has ever been accused of figuratively standing on the shoulders of other chimps to develop a more complex or superior variant of this simple technology. Their technology, then, stagnates at this simple stage. Chimp-tech does not become increasingly complex, as ours has.

Language is a key reason for that. It allows us to convey to one another things unseen, things abstract, things happening in different times and places—even things happening only in our heads. Most animal communication, in contrast, is of the “watch out for that tiger,” “hand over that banana,” or “let’s get it on” ilk—it deals with immediate and present physical needs. Animals do not discuss quantum mechanics, or Fauvism, or the theory of mind; they do not discuss anything that is not the here and now.

Language shapes the way we think; it enables us to think complex thoughts, not only to convey them. Animals have never needed to do that since their cultures never became complicated enough to require symbolic language to transmit. Even if they have a suite of behaviors that can be called culture, it is not culture worth their talking about.

Laland cites evidence for this cultural drive theory using mathematical models, and computer simulations. (The chapters Darwin’s Unfinished Symphony devotes to animal studies that have contrasted the copying abilities of threespine stickleback fish and ninespine stickleback fish can be pretty dry.) His contribution is to realize that the spark that got the whole thing started were innovations in food-processing techniques that let us get more energy from our diet. More efficient eating allowed for brain growth, an extension of lifespan, and population growth. These, in turn, enabled more technological innovations, since both the people and the technologies hung around long enough for innovations to be made. Hence language evolved as the best way to teach these innovations, hence bigger brains evolved to learn the language. But in the end, it’s all food’s fault.

So when your fourth grader (or seventh grader, or 12th grader) comes home whining about why does she have to know about the Pax Romana (or the endoplasmic reticulum or differential equations)—what use will she ever have for this information?—remind her that learning this stuff in school is what makes us uniquely human. Just hope that she isn’t clever enough to realize that Snapchatting instead of doing homework is uniquely human, too.