Let’s start with cousins. Everyone knows, you can’t marry your cousin.
Biologists have long observed that closed breeding populations accumulate weaknesses over generations. Inbreeding produces brittleness. Our DNA is wired to falter when the inputs are too narrow. Nature’s instruction manual has one non-negotiable rule written into every strand of the double helix: go forth and diversify.
This is not a comment about who should marry whom. It is an observation about what happens to any closed system—biological, economic, or civilizational—when it cuts itself off from outside inputs. Weakness accumulates. Adaptation stalls. The system becomes fragile in exact proportion to its isolation.
We Have Always Been Traders
Long before capitalism, before nation-states, before the word “trade” carried any ideological baggage, human beings were exchanging things across distances that should have been prohibitive.
Archaeologists have found obsidian—volcanic glass, sharper than steel when fractured—hundreds of miles from the nearest geological source. Stone Age communities were not isolated knuckle-dragging hermits. They were network participants. Goods moved. Skills followed. Ideas traveled in their wake. Before agriculture, before writing, before the wheel, we were traders. It is part of what makes us us.
The pattern holds throughout all of history. The Silk Road moved silk and spice between East Asia and the Mediterranean. It also moved knowledge: ideas compounding as they passed from brain to brain; brains that had marinated in different cultural sauces creating distinct intellectual flavorings as those ideas moved. Buddhism traveled from India into China. Science and philosophy from the Muslim world to medieval Europe. The civilizations that grew most dynamic were the ones that absorbed what they encountered, not the ones that sealed their borders against it.
After 1492, the Columbian Exchange reshuffled the world yet again. Potatoes transformed Europe. Maize spread across Africa. And then there are the examples that expose just how completely trade rewrote the identities of civilizations we think of as ancient.
Try to imagine Italian cuisine without tomatoes. Try to imagine Indian food without chili peppers.
Both originated in South America. Both were unknown to Europe and Asia five hundred years ago. Today, a Neapolitan grandmother would fight you over her marinara as if Julius Caesar himself had dictated the recipe. A street vendor in Hyderabad would be personally offended by the suggestion that his ancestral spice palette arrived on a Portuguese ship.
That is what exchange does. It transforms the receiver so completely, and at such a pace, that the foreign origins of goods and ideas tend to get erased from memory.
Someone might raise a fair objection: some closed systems can work. They might point to Tokugawa Japan, which sealed itself off for over two centuries and maintained remarkable stability. Yet stability is not dynamism. And when Commodore Perry’s ships appeared in 1853, Japan’s isolation had left it technologically outmatched—it took one afternoon to force open doors that had been shut for two hundred and fifty years.
The Meiji leaders who came after that fateful encounter etched an entirely different lesson on the Japanese mind: open up fast or we die.
The American Irony
This is why I have such a hard time understanding American nationalism. No country on earth has benefited more from open exchange than the United States. The American story is a story of mixture. Wave after wave of immigrants arrived carrying skills, languages, capital, and the entrepreneurial intensity of people with everything to prove. German engineers, Chinese railroad workers, Jewish merchants, Italian farmers, Irish laborers—each community added something the composite whole now takes for granted.
Imagine America without the Blues. Without Jazz. Without Jewish humor. Without sushi and the Japanese 5S system of plant management. Without burritos and salsa. Without Taiwanese semiconductors or boba milk tea. Without German beer or the theology of Martin Luther. I can scarcely imagine the pale bland blah that would remain. It is precisely our national jambalaya that makes this place interesting—and powerful.
Biologists call this hybrid vigor: cross two genetically distinct lines and the offspring tend to be stronger, more adaptable, more resilient than either parent. America is full of hybrid vigor. A mutt. A gorgeous, chaotic, perpetually unfinished mix of everything the world has to offer.
Our economy is strong because we let all ideas, and all people with ideas, in. Our population is resilient because our gene pool—cultural, intellectual, and yes, genetic—draws from everywhere. That is not a vulnerability. It is the reason Silicon Valley exists, the reason American universities dominate global rankings, the reason American culture gets exported to every corner of the planet. Openness is what built America.
Nationalism is not entirely irrational. It can be a response to real dislocation, to communities genuinely hurt by transitions they didn’t choose. That pain deserves to be taken seriously. But nationalism mistakes insulation from change for resilience to it. The current nationalist project proposes to close the borders to goods and to people; to seal off the economy and the culture. It is the equivalent of deciding, at the species level, that we should all start marrying our cousins again.
Every biologist on earth would tell you that’s a path to ruin. Every economic historian worth reading would say the same about our civilization.
From Obsidian to Algorithms
Today the traded commodity is no longer volcanic glass. It’s more likely to be code. Algorithms cross borders in milliseconds. Consider the chip inside your phone: designed in California, built with lithography machines from the Netherlands, fabricated in Taiwan, assembled in China, running software written by teams scattered across a dozen time zones. No single country could produce it alone. The device in your pocket is the entire history of human exchange—obsidian to algorithms—compressed into one palm-sized object.
Human beings survive by connecting. We grow by exchanging. We build resilience not by sealing ourselves off from the world’s complexity but by engaging it, absorbing it, and making something better from the encounter.
That is our four-hundred-thousand-year track record. Both our genes and our history agree on this point.
The only people who disagree are the ones proposing to ignore both.