The Monoculture Trap: Why Bangkok and London Suffer the Same Disease
A coral reef with 500 species can absorb a bleaching event and regenerate. A reef dominated by a single fast-growing coral cannot. The colony looks impressive right up until the water temperature shifts two degrees—and if that species happens to be vulnerable, the whole structure collapses with no fallback.
This is the story of two economies that look nothing alike on the surface but share the same structural disease underneath. Thailand, a middle-income Southeast Asian manufacturing hub ranked 29th on Harvard's Economic Complexity Index, and the United Kingdom, a high-income services economy ranked 10th. Different continents, different income levels, different histories. Same pathology.
Both nations funnelled their most complex economic activities into a single dominant city. Both starved their secondary cities of the capabilities needed to develop independent economic complexity. And both are now discovering what ecologists have known for decades: monocultures are efficient until they collapse.
The Primate City Problem
In 1939, geographer Mark Jefferson coined the term "primate city" for an urban area at least twice the size and more than twice as important as the next largest city in a country. Bangkok and London don't just meet this threshold. They obliterate it.
Bangkok's urban agglomeration dwarfs every other Thai city—depending on the boundary definition, anywhere from ten to thirty-five times larger than Chiang Mai.[1] The wider Bangkok Metropolitan Region generates roughly half of Thailand's GDP with about a quarter of its population. It captures 48% of the country's service sector. Thailand's fiscal structure is among the most centralised in Asia-Pacific, with subnational governments accounting for just 4% of GDP in public expenditure. Nearly every major bank, multinational headquarters, and government institution operates from a single postcode.
London's dominance is less extreme in population terms—roughly four times Birmingham—but its economic gravity is crushing. London produces about a quarter of UK GDP. Its economic output per person, at £69,077, sits roughly 75% above the national average—a premium that has doubled since the 1980s.[2] London and the South East are the only two UK regions with a net fiscal surplus. The rest of Britain runs on transfers.
Biology has a name for this pattern. When a network grows by preferential attachment—new connections favouring nodes that already have the most connections—you get a network with a few massive hubs and many starved peripheries. The structure becomes extraordinarily efficient for routing through the hub and extraordinarily fragile if that hub fails.
Bangkok and London are hubs with no spokes. Andy Haldane, former chief economist of the Bank of England, used exactly this phrase to describe the UK's economic geography. It applies equally to Thailand.
What Economic Complexity Actually Measures
The Economic Complexity Index measures what GDP misses: not how much a country produces, but how sophisticated and diverse its production is. A country that exports oil and not much else scores low regardless of its wealth—like a student who aces one subject. A country that exports pharmaceuticals, precision instruments, specialty chemicals, and software scores high—like a student who excels across the entire curriculum. Those products require layered expertise that only develops over decades.
The insight that matters here is not the national ranking. Thailand sits at 29th (ECI score 0.96); the UK at 10th. The insight is what happens within each country.
A 2020 study in Nature Human Behaviour showed that complex economic activities—biotechnology, semiconductors, financial engineering—concentrate disproportionately in large cities.[3] Complexity explained between 40% and 80% of the variance in urban concentration across US metropolitan areas. Using patent data going back to 1850, the researchers showed that this spatial concentration has increased over time. The more complex the economy becomes, the more it concentrates. Complexity and urbanisation form a ratchet: each turn pulls more capability toward fewer places.
This finding reframes the primate city problem. Bangkok and London don't just have more people and more money. They have captured the capabilities—the tacit knowledge, specialised labour pools, institutional networks—that produce complex economic output. The rest of each country is left with simpler activities: agriculture, basic manufacturing, routine services.
Two Countries, One Disease
Here is where the Thailand-UK parallel sharpens.
Thailand's trap: Between 1970 and 1985, Thailand achieved one of the most remarkable jumps in economic complexity ever recorded—a full standard deviation increase in its ECI score, driven by the shift from agricultural exports to electronics, automotive parts, and machinery.[4] This complexity, however, concentrated almost entirely in Bangkok and its surrounding industrial corridor. Thai secondary cities remain fiscally dependent on central government transfers. Despite decentralisation legislation in the 1990s, local governments lack the autonomy to finance infrastructure or attract investment independently. Bangkok's per capita GDP is 6.5 times that of Thailand's poorest region, the Northeast.
The result: Thailand's national ECI has flatlined—the metabolic equivalent of an organism that stopped growing new tissue and is now simply maintaining existing structure. The country displays classic middle-income trap symptoms—productivity growth has slowed, university enrolments are falling, and its automobile industry consists primarily of foreign assembly operations with limited domestic technology transfer.[5] Thailand produces cars but doesn't design them. It assembles hard drives but doesn't architect chip layouts. The complex capabilities remain in Japan, South Korea, and Germany—or in the boardrooms of Bangkok. The national economy is like a tree with one massive branch and a withered root system: impressive canopy, fragile foundation.
The UK's trap: The UK's version of the same disease is subtler because it operates at a higher income level. UK manufacturing declined from 33% of GDP after World War II to about 8%. The 1986 Big Bang deregulation of financial services accelerated London's dominance while regions like the Midlands and Yorkshire lost their industrial complexity virtually overnight.[2]
The Centre for Cities applied Hausmann and Hidalgo's framework directly to British urban economies and found that of the eighteen largest French and German cities, all had high economic complexity. In Britain, only three of nine large cities (Bristol, Leeds, Manchester) exceeded the European average.[6] Manchester has improved the most, rising from 52nd to 18th most complex British economy since 1981. But even Manchester and Glasgow still underperform their European peers. Britain's secondary cities are complex by British standards and mediocre by continental ones.
The UK is now the most geographically unequal industrialised economy in terms of GDP per capita, productivity, and disposable income. The gap between London and the rest of the UK is larger than between East and West Germany, or between North and South Italy.[2]
The Biological Diagnosis
Ecologists use the term "response diversity" to describe a critical property of resilient ecosystems: functionally similar species that respond differently to environmental shocks. A forest with twenty tree species can lose five to drought and still function as a forest. A plantation of a single species cannot.
Coral reefs are the textbook example. A healthy reef supports hundreds of coral species, each with different thermal tolerances. When water temperatures spike, heat-sensitive species like Acropora bleach and die while hardier species like Porites tolerate the change. The reef degrades but persists—its diversity acts as a portfolio of bets against an uncertain future. A reef dominated by a single fast-growing species has no such hedge. If that species proves vulnerable, there is no fallback. The entire structure fails at once.
Bangkok and London are economic monoculture reefs. They look spectacular—vibrant, productive, world-class. But strip away the dominant city and both nations reveal the same structural vulnerability. If London's financial services contracted by 30% (as happened during the 2008 crisis, when sterling fell nearly 30%), there is no Birmingham or Manchester complex enough to compensate. If Bangkok's tourism and services sector collapses (as happened during the COVID-19 pandemic, when Thailand's GDP fell 6.1%), there is no Chiang Mai or Khon Kaen with the capability to absorb the shock.
Contrast this with Germany, where economic complexity is distributed across Munich, Stuttgart, Hamburg, Frankfurt, Berlin, Cologne, and dozens of mid-sized cities, each with specialised capabilities. The German economy resembles a mycorrhizal network—the underground fungal web that connects forest trees. In a mycorrhizal network, phosphorus and carbon flow preferentially toward nutrient-stressed nodes: a shaded sapling receives sugars from a sun-drenched mature tree through fungal hyphae, not because a central allocator decided to help, but because concentration gradients drive resources toward deficit. Germany's fiscal transfer system operates similarly—richer Länder fund poorer ones—but the deeper parallel is structural: the network itself distributes capability, not a central planner. When one node suffers, others compensate. This is not because German cities are individually more impressive than London. It is because the network has response diversity that Britain and Thailand lack.
How the Trap Self-Reinforces
The primate city trap is self-reinforcing through three biological mechanisms operating simultaneously.
First, preferential attachment accelerates. Complex firms need specialised talent. Specialised talent concentrates where complex firms already exist. Each new hire in London or Bangkok makes the next hire more likely to happen there. The network grows by adding connections to the most connected node, widening the gap with every cycle.
Second, competitive exclusion takes hold. In ecology, the competitive exclusion principle states that two species competing for the same niche cannot coexist indefinitely—one will displace the other. Cities are not identical species in identical niches. But when Bangkok and London offer deeper talent pools, better infrastructure, and proximity to decision-makers, they create such asymmetric competition that secondary cities cannot attract the same complex activities. Birmingham doesn't fail because it's doing something wrong. It fails because London is doing the same thing with structural advantages that compound over time—the urban equivalent of a dominant species out-competing a smaller population for the same food source.
Third, source-sink dynamics drain the periphery. Talent, capital, and institutional capability flow from peripheral regions (sources of human capital) to the primate city (the sink that absorbs it). Young graduates leave Chiang Rai for Bangkok, leave Newcastle for London. The peripheral regions fund education; the primate city captures the returns. Over decades, this drains the periphery of exactly the capability it would need to develop economic complexity of its own.
What Has Been Tried, and Why It Fails
Both countries have attempted policy responses. Thailand passed decentralisation legislation in the 1990s. The UK launched its "Levelling Up" agenda in 2022. Neither has reversed the underlying dynamic.
The reason is biological. Both policies attempted to redistribute output—money, jobs, infrastructure projects—without redistributing capabilities. In complexity terms, they tried to move the products without moving the knowledge required to produce them.
The Centre for Cities research makes this explicit: places that "doubled down" on a single sector without broadening their export base saw complexity decline even when that sector performed well.[6] Building a factory in a secondary city creates jobs. It does not create the dense network of specialised suppliers, research institutions, and skilled labour that produces economic complexity. The factory is a branch of the primate city's ecosystem, not a root of a new one.
The World Bank's 2023 assessment of Thailand reaches the same conclusion from a different direction: secondary cities need fiscal autonomy, local decision-making authority, and the ability to attract investment independently.[1] Without these, they remain wards of Bangkok—sinks that consume transfers rather than sources that generate complexity.
The Agglomeration Defence—and Its Limits
The standard defence of primate city concentration is that agglomeration effects are real. Complex activities cluster because proximity generates knowledge spillovers, thicker labour markets, and shared infrastructure that make everyone more productive. London and Bangkok genuinely benefit from agglomeration, and so do their countries—up to a point.
The biological parallel is instructive. A large colony of social insects benefits from division of labour and economies of scale. But past a certain size, every colony faces diseconomies: congestion, resource depletion, communication breakdown. Ant colonies solve this by budding—spinning off satellite colonies that maintain network connections while developing local autonomy.[7]
The question is not whether London and Bangkok benefit from agglomeration. They clearly do. The question is whether the marginal return on concentrating the next unit of complexity in the primate city exceeds the marginal return on developing complexity elsewhere. Biology suggests there is a tipping point—the point where efficiency gains from concentration are outweighed by fragility costs from lost response diversity.
Geography mediates where that tipping point falls. Germany's navigable river network—the Rhine, Elbe, Danube, and their tributaries—distributed trade across dozens of inland cities for centuries, creating the conditions for polycentrism long before industrial policy existed. Thailand's geography, with one dominant river basin and one deep-water port region, naturally funnels activity toward Bangkok. But geography is not destiny. The Netherlands is flat, small, and concentrated—yet built one of Europe's most polycentric economies through deliberate infrastructure and institutional design. Both Thailand and the UK appear to have crossed the tipping point, and both have the institutional capacity to respond—if they choose to.
Building the Alternative
Biology suggests that the solution is not to shrink the primate city but to grow the network around it. The countries that have avoided the primate city trap share a common feature: distributed complexity developed through specialisation, not replication.
The Netherlands compresses finance (Amsterdam), government and international law (The Hague), port logistics (Rotterdam), and high-tech manufacturing (Eindhoven) into a polycentric network smaller than Greater London. Eindhoven didn't try to replicate Amsterdam's financial sector. It built a semiconductor and lighting ecosystem around Philips and later ASML that now generates more patents per capita than almost any European city. South Korea, despite Seoul's dominance, developed Busan as a maritime hub, Daejeon as a government science campus that incubated over 2,000 companies, and the semiconductor corridor around Suwon.
Thailand has one partial success of its own. The Eastern Seaboard Development Board, established in the 1980s, built an automotive assembly corridor around Laem Chabang and Rayong—deliberately outside Bangkok. By concentrating port infrastructure, supplier parks, and technical training in a specific region, it attracted Toyota, Honda, and Ford to build factories that now make Thailand the largest auto producer in Southeast Asia. The approach worked because it built specific capability (automotive manufacturing ecosystems) rather than trying to replicate Bangkok's generalist services economy. The limitation: the corridor remained an assembly operation, not a design centre. The complex capabilities—engineering, R&D, brand strategy—stayed in Tokyo and Detroit.
Manchester's rise from 52nd to 18th most complex British economy offers a complementary blueprint. The BBC's relocation to Salford in 2011 seeded a media cluster. University investment attracted research capability. Transport improvements (though still inadequate compared to continental peers) created connectivity. The result was not a smaller London but something different—a media and digital services hub with lower costs and distinct capabilities.
The biological prescription for both Thailand and the UK is the same: build response diversity by developing different complex capabilities in secondary cities rather than trying to replicate what the primate city already does. Manchester should not try to become a smaller London. It should become something London cannot be. Chiang Mai should not try to become a smaller Bangkok. It should develop capabilities that Bangkok's congestion and cost structure cannot support.
When Darwin's finches reached the Galápagos, they didn't all compete to be the best seed-cracker. They radiated into thirteen species, each filling a niche the others ignored. Warbler finches eat insects. Woodpecker finches use cactus spines as tools. This is adaptive radiation—diversification into distinct ecological niches. It requires two conditions: opportunity (open niches that the dominant species doesn't occupy) and separation (enough distance from the dominant competitor to develop independently before being reabsorbed).
Both conditions are policy-achievable. Fiscal devolution creates separation. Specialised infrastructure creates opportunity. But neither works without accepting the core biological insight: you cannot build a resilient ecosystem by making every part of it look like the dominant species. You build resilience by making the parts different.
The Uncomfortable Conclusion
Harvard's Growth Lab research predicts that countries whose economic complexity exceeds their income level will grow faster, while those that are "too rich" for their complexity will stagnate. Thailand is stuck at middle income with complexity that hasn't advanced in decades. The UK has world-class complexity in London and mediocre complexity everywhere else, producing a national average that masks a structural disease.
The parallel between these two economies is not a coincidence. It is the same mechanism operating at different income levels. Preferential attachment funnels capability to the largest node. Source-sink dynamics drain the periphery. Competitive exclusion prevents secondary cities from developing. Path dependence locks in the pattern.
A coral reef does not become resilient by growing its largest colony bigger. It becomes resilient by cultivating diversity across the whole structure. Until Thailand and the UK grasp this distinction—between concentrating excellence and distributing capability—they will remain trapped. Different income brackets. Same monoculture. Same vulnerability.
Related mechanisms: preferential-attachment | source-sink-dynamics | response-diversity | path-dependence | adaptive-radiation | competitive-exclusion
Related organisms: coral | mycelium | ant-colony
Sources
World Bank, "Thailand's Smaller Cities Can Help Drive Economic Growth and Reduce Inequality," Press Release, September 2023. ↩
Zymek, R. and Jones, B., "Tackling the UK's Regional Economic Inequality: Binding Constraints and Avenues for Policy Intervention," Harvard Kennedy School Mossavar-Rahmani Center Working Paper No. 198, 2023. ↩
Balland, P-A., Jara-Figueroa, C., Petralia, S., Steijn, M., Rigby, D., and Hidalgo, C., "Complex economic activities concentrate in large cities," *Nature Human Behaviour*, Vol. 4, 2020. ↩
Hausmann, R. and Hidalgo, C., *The Atlas of Economic Complexity: Mapping Paths to Prosperity*, MIT Press, 2011. ↩
South China Morning Post, "Why Thailand Failed to Escape the Middle-Income Trap," 2024. ↩
Centre for Cities, "What Levelling Up Really Means: Changing the Geography of Knowledge," 2022. ↩
Hölldobler, B. and Wilson, E.O., *The Superorganism: The Beauty, Elegance, and Strangeness of Insect Societies*, W.W. Norton, 2009. ↩