Mesopotamia
Irrigation created the first cities, writing, and empires—then salinization destroyed them. Mesopotamia's 5,000-year boom-bust cycle now depends on Turkish dams.
Mesopotamia invented civilization and then salted the earth beneath it. The irrigation that created the world's first cities—Uruk reached 100,000 inhabitants by 3000 BCE—also poisoned the soil that fed them. Writing emerged here not from poetry or philosophy but from the need to track barley rations. Positive feedback loops drove the cycle: irrigation enabled surplus, surplus enabled cities, cities enabled specialization, specialization enabled innovation, and innovation enabled more irrigation. Each turn of the wheel concentrated more salt in the soil.
The Tigris and Euphrates offered unpredictable abundance. Unlike the Nile's gentle annual floods, these rivers surged violently, depositing fertile silt but also destroying settlements. The solution—canals, levees, drainage systems—required coordination at a scale no human society had attempted. Temple priests became administrators, administrators became kings, and kings built the first empires. By 2400 BCE, the region's city-states had developed sophisticated bureaucracies managing irrigation schedules, labor corvées, and grain distribution across territories spanning modern Iraq, Syria, and southeastern Turkey. The innovations born here—writing, the wheel, codified law, urban planning—became founder effects that shaped every subsequent civilization.
By 2400 BCE, Sumerian farmers were abandoning wheat for salt-tolerant barley—the first documented evidence of stress accumulation forcing agricultural adaptation. By 1700 BCE, even barley yields had collapsed. Southern Mesopotamia's population fell by 60%, and political power shifted northward to Babylon, then Assyria—following the retreating zone of viable agriculture. This pattern of ecological succession repeated across three distinct salinization crises: southern Iraq from 2400-1700 BCE, central Iraq from 1200-900 BCE, and the Baghdad region after 1200 CE. Each empire inherited the irrigation infrastructure of predecessors; each eventually exhausted the soil or lost control of the water.
Hammurabi's Code (1755-1751 BCE) codified property rights and commercial transactions—legal foundations that still underpin contract law in modern Iraq and across the world. Successive empires rose on this template: Sumerians, Akkadians, Babylonians, Assyrians, Persians, Greeks under Alexander, Romans, Arab caliphates, Mongols, Ottomans. The niche construction that enabled each civilization also constrained the next.
The modern inheritors face a familiar pattern accelerated by geopolitics. Turkey's Southeastern Anatolia Project includes 22 dams on the Tigris and Euphrates, reducing downstream flows by more than half since the 1970s. Iraq now faces its worst drought in 90 years, with 60-70% of formerly irrigated land degraded by salinity. The November 2025 oil-for-water framework agreement—trading Iraqi crude for Turkish infrastructure investment—reprises a dependency pattern as old as the first Sumerian canals: those who control the headwaters control the civilization downstream. The feedback loop continues, but now the upstream constraint is political rather than environmental.
Biological Parallel
Mesopotamia exemplifies niche construction that backfires: humans transformed the landscape to maximize agricultural output, but accumulated salt stress forced successive civilizations to shift to more tolerant but less productive species—just as barley replaced wheat as soils degraded. The region's history is the story of organisms adapting to environmental pressures they created themselves.