Narrator: Imagine being stuck in the gridlocked streets of Jakarta, late for a meeting. Your taxi driver, desperate to move, pulls over. A woman carrying a baby gets in, but she doesn't speak to you or the driver. She’s not a passenger in the traditional sense. Instead, her presence allows the taxi to legally use the high-occupancy carpool lane, bypassing the traffic. At the end of the ride, the driver pays her a small fee. In this single, strange transaction, money isn't just a payment; it's a social lubricant, a creator of temporary relationships, and a solution to a problem, binding three strangers together in a shared, momentary goal. What is this force that can create such unexpected connections?

This question lies at the heart of Kabir Sehgal's book, Coined: The Rich Life of Money and How Its History Has Shaped Us. Sehgal argues that to truly understand money, we must look beyond economics and see it as a reflection of our biology, our psychology, and our deepest cultural values.

Narrator: Long before humans invented markets, nature had already perfected the art of exchange. Sehgal takes us to the Galápagos Islands, a living laboratory of evolution, to reveal that exchange is a fundamental biological process. In the vibrant marine ecosystems, he observes a sea turtle patiently waiting as small wrasse fish swarm its shell. This isn't a random encounter; it's a transaction. The fish get a meal by cleaning parasites and algae off the turtle, and in return, the turtle gets a vital health service. This symbiotic relationship, a form of biological trade, is essential for the survival of both species.

This principle of cooperation, driven by mutual self-interest, is not an exception but a rule in nature. It’s a concept explored in the famous "Prisoner's Dilemma" game, where two captured prisoners must decide whether to betray each other or cooperate. While betrayal might seem logical in the short term, repeated simulations show that the most successful long-term strategy is "Tit for Tat"—cooperating on the first move and then mirroring your opponent's actions. This demonstrates that cooperation is an evolutionarily advantageous strategy. For early humans, this drive to cooperate led to the creation of tools, language, and eventually, the abstract concept of money as a tool to facilitate ever more complex exchanges.

Narrator: For decades, economic models were built on the idea of Homo economicus—the perfectly rational human who always makes logical, self-interested decisions. But the 2008 financial crisis shattered this illusion. Even Alan Greenspan, the former Chairman of the Federal Reserve, admitted his shock, acknowledging that his belief in the self-correcting power of rational markets was flawed. The crisis revealed that human decision-making is driven by something far more primal: emotion and cognitive bias.

Sehgal explores the fields of behavioral economics and neuroeconomics to explain why. Neuroeconomist Brian Knutson at Stanford University conducted experiments using fMRI scanners to watch people's brains as they made financial decisions. He found that the anticipation of a monetary gain activates the nucleus accumbens, the same pleasure center of the brain stimulated by food, sex, and drugs. Conversely, the prospect of a loss triggers the anterior insula, a region associated with pain and disgust. This research shows that our financial choices are not cold calculations but a battle between greed and fear, played out in our neural circuitry. Money, it turns out, has conditioned us like Pavlov's dogs; the mere prospect of it can hijack our rational thought.

Narrator: Conventional wisdom holds that money was invented to replace inefficient barter systems. However, Sehgal, drawing on anthropological research, argues that this story is likely a myth. Instead, the history of money is deeply intertwined with the history of debt, not as a financial instrument, but as a social one. Long before coinage, human societies were held together by a complex web of mutual obligations.

A powerful example of this is the potlatch ceremony of the Kwakiutl people in the Pacific Northwest. During a potlatch, a chief would host a lavish feast and give away vast quantities of wealth—blankets, canoes, and other valuable items—to his guests. This wasn't simple generosity; it was a display of power and a way to create social debt. By accepting the gifts, the guests were obligated to reciprocate with an even more lavish potlatch in the future, reinforcing the social hierarchy and binding communities together. This "gift economy" operates on a logic entirely different from a market economy. It shows that for much of human history, exchange was about building relationships and social status, not just accumulating profit. Financial debt, recorded in silver, only emerged later, but the underlying concept of social obligation was already ancient.

Narrator: The physical form of money has undergone a dramatic evolution, from "hard money" with intrinsic value to "soft money" backed only by faith. The story begins in ancient Lydia, where the first coins were minted from electrum, a natural alloy of gold and silver. These coins were valuable because the metal itself was valuable. Roman emperors later discovered they could "debase" their currency by mixing cheaper metals into their silver coins, allowing them to fund wars and projects but eventually causing inflation.

The ultimate leap to soft money came with paper currency. In the 13th century, Kublai Khan introduced paper money across his vast empire in China. As Marco Polo observed, Khan forced his subjects to accept these notes on pain of death. Initially, the system worked, but the temptation to print more money to cover expenses proved too great. The government printed notes excessively, leading to hyperinflation and the collapse of the currency's value. This story represents the "Faustian bargain" of soft money. It offers incredible convenience and power to the issuer, but it carries the constant risk of overproduction and ruin. This same dynamic played out in revolutionary France and continues today, as modern central banks manage the supply of fiat currencies like the U.S. dollar, which was permanently severed from its gold backing in 1971.

Narrator: Ultimately, Sehgal argues that money is more than a biological impulse, a psychological trigger, or a historical artifact; it is a symbol of our values. The "soul" of money is revealed in what we choose to do with it and what we choose to represent on it. Major world religions, for instance, offer a "spiritual logic" that directly counters the economic logic of "more is better." Christianity, Judaism, and Islam all warn against the love of money, framing wealth as a moral test and advocating for charity and detachment as paths to true richness.

This symbolic power is also etched directly onto our currency. The art on coins and bills serves as a guide to a nation's collective past and its aspirations. In Bangladesh, archaeologists unearthed ancient punch-mark coins from a lost city near Wari-Bateshwar. The symbols on these coins—boats, fish, and suns—tell the story of a thriving maritime civilization that existed over two thousand years ago. Similarly, the American "double eagle" $20 gold piece, designed in the early 20th century, was intended to be a triumphant symbol of national unity and strength. By studying the art on money, we can read the stories a nation chooses to tell about itself, transforming a simple medium of exchange into a powerful cultural document.

Narrator: Across its sweeping, multidisciplinary journey, Coined arrives at a powerful and unifying conclusion: money is, first and foremost, a symbol of value. It is an abstraction, a shared idea that allows us to convert the physical world of goods and the biological drive for survival into a system of belief. Whether it's the trust in a sea turtle to remain still for its cleaning, the faith in a government not to devalue its currency, or the belief in a set of national ideals printed on a bill, money operates on the power of collective agreement.

The book challenges us to look at the bills in our pockets not just as tools for buying, but as artifacts carrying the weight of our biology, our psychology, and our collective values. The ultimate question it leaves us with is not just what money is, but what we want it to be. What values are we, as a society, encoding in our money today?