Today this kind of behavior is taken for granted, and the commerce it generates is the basis of the world’s economy. But humans’ economic transactions, such as those at Oued Djebanna, go beyond every other species’: No other animal does it. Even in our extinct and big-brained cousins the Neanderthals, who were alive at the same time as these bead-trading humans of Algeria, there is no compelling evidence of symbolic behavior or trade apart from a few scattered instances of flower petals in shallow graves.
The reason might be that even the simplest of exchanges requires a sophisticated set of rules and understandings: How can I trust you to give me something of equal value for my shells? How do I know you won’t steal my goods and just run off? And how do we ever agree in the first place on the worth of our respective items?
This last question is in some ways the most important because the answer might just explain another enigma about humans: our possession of language. Just as we are the only species to have complex systems of trade and exchange, we are also the only species that has language, and it might just have its origins in our earliest economic behaviors.
Some might argue that language, and in turn trade, naturally emerge from the general-purpose cognitive mechanisms that came with evolving brains. But language is so specialized and trade is so advantageous that there is reason to believe natural selection zeroed in on speech as a handy adaptation. I like to think of our language as a piece of social technology, developed for managing the demands of the sophisticated social lives based on trade and specialization that our species was evolving. Perhaps we acquired language—and no other species did—because we were the only species with something to talk about.
Here is my reasoning. All animals communicate, whether it be via grunts, whistles, barks, chest thumps, bleats, odors, colors, chemical signals, chirrups, or roars. These familiar sights, sounds, and smells can vary in their intensity and persistence. They might signal an animal’s status or intentions, or indicate its physical prowess; they might tell a predator it has been spotted, or send a message to nearby relatives about an imminent danger.
Human language, on the other hand, is compositional: We alone communicate in sentences composed of discrete words that take the roles of subjects, verbs, and objects: “I kicked the ball.”; “She programmed the computer.” Unlike animal communication, our language allows us to combine and recombine subjects, objects, and verbs to make an endless variety of messages: “I kicked the computer.”
Thus, your pet dog can tell you it is angry, and even how angry it is, but it cannot recount its life story. By comparison, we can use our language to look into the future, share the thoughts of others, and benefit from the wisdom of the past. We can make plans, cut deals, and reach agreements. We can woo prospective mates and threaten our enemies. We can describe who did what to whom, when they did it, and for what reason. We can describe how to do things, and what things to avoid. We can express irony, surprise, glee, worry, pessimism, love, hate, or desire. We can be witty or grave, precise or deliberately vague.