The Cognitive Revolution

We come now to the change that made us, and it is the hardest one in the whole book to explain, because it happened inside a skull and left the faintest of traces. Anatomically, our species was fully itself by around three hundred thousand years ago; a Homo sapiens from then, cleaned up and dressed in modern clothes, would pass unnoticed on any street in the world today. And yet, for a very long time after that, nothing much seems to have happened. The same simple stone tools, made the same way, for tens of thousands of years. The body was ready long, long before the mind did the particular thing that would set our kind apart. Anthropologists sometimes call this puzzle the sapient paradox: why the gap of two hundred thousand years or more between having a modern brain and finally acting like a modern human. What we are trying to name in this chapter is whatever crossed that gap: the awakening of the symbolic mind, the arrival of a creature that could take one thing and deliberately let it stand for another.

That sounds abstract until you realize it is the single most powerful trick any animal has ever performed. A symbol is a stand-in. A sound that means "lion" without any lion present. A smear of red ochre that means "me." A notch cut into a bone that means "the moon was full." Once a mind can do that, once it can let a thing represent a thing that it is not, and share that meaning with another mind, everything becomes possible: language, story, plans for a future that does not yet exist, promises, gods, laws, mathematics, money, this very sentence traveling from one head into yours. The whole towering edifice of human culture rests on that one humble, bottomless ability to make one thing mean another. No other animal does it to any comparable degree, and we do almost nothing else.

When did it begin? The honest answer is that we are still arguing about it, and the argument turns on scraps recovered from the dirt. In a cave called Blombos on the South African coast, someone around seventy-three thousand years ago ground red ochre into a paste, and on a small flake of the stone scratched a careful, deliberate cross-hatched design, a grid of lines that is not a picture of anything at all. It is simply a made pattern, a mark created for the sake of meaning, and it is tens of thousands of years older than the famous painted caves of Europe. In the same layers, and at other African sites reaching back perhaps a hundred thousand years or more, people were piercing tiny seashells and stringing them to wear, and a bead worn on the body is already a symbol, already a silent sentence about who its wearer is, which clan, which status, which self. The symbolic mind, we now think, did not switch on all at once in a single European dawn, as an older and frankly rather self-flattering story used to have it. It flickered and smouldered and gathered in Africa across tens of thousands of years before it finally caught and blazed.

At the very heart of the change, and the deepest unsolved problem within it, is language. Somewhere in this long dark window, human beings began to speak: not merely to signal danger or desire as many animals do, but to combine a small set of sounds, by rules, into a genuinely limitless range of meanings, and to talk about what is not here, what is long past, what is only imagined, what is deliberately false. Language is the master symbol system, the one that makes all cumulative culture possible, because it lets one mind pour its hard-won discoveries directly into another, and lets each new generation begin where the last one left off rather than starting from nothing. And we do not know how it began. The origin of language has been called, only half in jest, the hardest problem in all of science, because speech leaves no fossils. We can dig up the throats and the skull-shapes and even trace some of the genes that made fluent speech possible, but the thing itself, the first true sentence, vanished on the air the instant it was spoken and left not a trace in the ground. We can say with confidence that it happened, that it changed absolutely everything, and that it has since flowered into the roughly seven thousand distinct languages humans speak today. We cannot yet say how the first miracle was worked.

There are serious ideas, and we will give each its true weight and no more. One genuinely intriguing proposal is that we partly domesticated ourselves: that across this long span our species was selected, generation upon generation, against the reactively aggressive and hot-tempered and in favor of the calm, the tolerant, the cooperative, in much the way we would later breed the wildness out of wolves to make dogs, and that a gentler, more group-minded animal was the necessary vessel into which language and shared culture could finally be poured. There is real evidence for this in our very anatomy, the softening of the heavy brow, the shrinking of the face, changes that track the taming of other species. At the far, wilder end of the spectrum sits the notion that psychedelic mushrooms triggered the leap in human cognition, an idea with a devoted following and essentially no solid evidence behind it, which we name here only because honesty requires us to say both that it is out there and that the science does not support it. Between the credible and the fringe lies most of the truth we can actually claim: the symbolic mind arose gradually, in Africa, out of some braid of social, ecological, and biological pressures that we have not yet fully untangled and may never entirely resolve.

What we can do, and what the rest of this Part will do, is watch what the awakened mind did next, because there it stops being invisible and starts leaving its evidence all over the walls of the world. Once the symbolic animal possessed language and imagination, it began to lay the contents of its inner life out in the open: in ornament, in instrument, in ritual, in the treatment of its dead, and above all in image. It began to make art. And art, unlike a spoken sentence, can survive forty thousand years in the dark and still stop us where we stand.