O.K., who ordered that? With everything else going on, the last thing we needed was a new economic crisis in a country already racked by political turmoil. True, the direct global spillovers from Turkey, with its Los Angeles-sized economy, won’t be large. But we’re hearing that dreaded word “contagion” — the kind of contagion that once caused a crisis in Thailand to spread across Asia, more recently caused a crisis in Greece to spread across Europe, and now, everyone worries, might cause Turkey’s troubles to spread across the world’s emerging markets.

It is, in many ways, a familiar story. But that’s part of what makes it so disturbing: Why do we keep having these crises? And here’s the thing: The intervals between crises seem to be getting shorter, and the fallout from each crisis seems to be worse than the last. What’s going on?

Before I get to Turkey, a brief history of global financial crises.

For a generation after World War II, the world financial system was, by modern standards, remarkably crisis-free — probably because most countries placed restrictions on cross-border capital flows, so that international borrowing and lending were limited. In the late 1970s, however, deregulation and rising banker aggressiveness led to a surge of funds into Latin America, followed by what’s known in the trade as a “sudden stop” in 1982 — and a crisis that led to a decade of economic stagnation.

Latin America eventually returned to growth (although Mexico had a nasty relapse in 1994), but, in the 1990s, a bigger version of the same story unfolded in Asia: Huge money inflows followed by a sudden stop and economic implosion. Some of the Asian economies bounced back quickly, but investment never fully recovered, and neither did growth.