Charles Kenny. Iron Curtain Fell

Mikhail Gorbachev turns 80 on March 2, and the collapse of the Soviet Union, over which he presided, celebrates its 20th anniversary this fall. In the intervening years, Gorbachev has put out an album, filmed pizza commercials, and founded a string of failed political parties. And with the benefit of two decades' worth of hindsight, the legacy of Gorbachev's accomplishment, however staggering, might seem a bit equivocal, too: rich, stable democracies in most of Eastern Europe, but also the increasingly czarist antics of Vladimir Putin and a miserable assortment of collapsing economies and vicious strongmen throughout the 'stans. And global tensions, from the Middle East to the Spratly Islands, have hardly gone away.

But Gorbachev has left one unambiguous legacy: Thanks to his actions, the world is a less violent place than it used to be. That's in large part because the end of the Cold War and the demise of the Soviet Union gave a considerable boost to the fortunes of democratization and multilateralism worldwide -- historical vectors that have produced a remarkable reduction in the amount of war in the world.

People have been killing each other since the dawn of humankind -- we may have eaten so many of our Neanderthal forebears that we drove them extinct. The advent of total war in the last hundred years brought this proclivity for violence to a bloody apex: Historian Niall Ferguson estimates that wars killed 800 times more people in the 20th century than in the 17th. But recently, our penchant for violence has dramatically reduced. Not only are murder rates well down, but so are war deaths.

The number of cross-border wars has been on the decline for awhile -- only four began between 1980 and 1989, and only one between 1990 and 1997, according to a recent paper in the International Studies Quarterly. Until recently, however, civil wars had taken up the slack. Between 1990 and 1997, the one new international war was dwarfed by the start of 24 civil wars. But now, even civil conflict is tapering off. The number of wars (of all kinds) ongoing worldwide, which increased from five in 1961 to 24 in 1984, had dropped back to five again by 2008.

The average number of deaths per war has also fallen considerably according to Bethany Lacina and Nils Gleditsch, researchers from the Center for the Study of Civil War. The average annual number of battle deaths per international conflict dropped from 21,000 in the 1950s to less than 3,000 in the new millennium, according to the Human Security Report of Canada's Simon Fraser University. That's a very partial accounting, because so many war-related deaths don't take place on the battlefield (the proportion is disputed, but some suggest as high as 90 percent). Nonetheless, the overall human toll of war has still declined, not least because the risk of war-related epidemics has shrunk. According to the Human Security Report, "today's armed conflicts rarely generate enough fatalities to reverse the long-term downward trend in peacetime mortality."

There is still far too much death and destruction around, of course -- the on-again, off-again civil war in the Democratic Republic of the Congo, which became the most deadly war of the new millennium over the course of five years of fighting, has killed somewhere between 1.8 million and 5.4 million people. And though the number of wars is rapidly on the decline, the number of armed conflicts too small to be categorized as a "war" -- those with between 25 and 1,000 battle deaths a year -- has declined more slowly and currently stands at around 35. That tally is considerably higher than it was in the 1960s or earlier and is even above what it was as recently as 2003 -- all of which suggests we should be wary of any claims about "the end of war."

Such (considerable) caveats aside, however, the accelerating global decline in warfare over the past 40 years is real -- and demands an explanation. One is that countries rarely fight over the things they used to. The only international war over territory since the end of the Cold War was between Ethiopia and Eritrea, suggested Ohio State University political science professor John Mueller in a recent article -- this despite a huge increase in the total number of states (including Eritrea). The number of colonial wars -- a category that constituted the majority of all wars fought in the 19th century -- has dropped to zero. Imperialism is well past waning, one high-profile (arguably) neo-imperialist adventure notwithstanding. Perhaps this is part of a growing recognition that state strength is no longer determined by acres under occupation but by economic performance.

Economics, in fact, may explain another part of the overall trend toward peace. In 1999, Thomas Friedman famously noted in The Lexus and the Olive Tree that no two countries that both had a McDonald's had gone to war. Naysayers have pointed out that a McDonald's-rich NATO alliance was willing to bomb Serbia, which had a restaurant of its own, and Russia and Georgia both had franchises before the South Ossetia conflict. But Friedman's broader point, at least, still largely holds true: The increasing strength of global economic ties makes war less attractive. Similarly, Rutgers University economics professor Carlos Sieglie and colleagues argue that trade and foreign direct investment between countries is associated with less chance of a war breaking out -- and there has been a lot more foreign investment of late.

Still, international trade and investment linkages can't help explain either the late 20th-century uptick or recent collapse in civil wars within countries. What can, perhaps, is a corollary to the increased interconnectedness of the global economy: the end of global ideological debate on forms of government that followed the fall of the Iron Curtain. The collapse of the Soviet Union and the end of superpower tensions ushered in dramatic global gains in respect for human and political rights. While the United States, as it did during the Cold War, has hardly shied away from supporting dictators when they were deemed to be geopolitically necessary, the number of countries that could be broadly considered democratic has doubled since the start of the 1980s. And democracies rarely go to war with other democracies, the thinking goes -- or at least they haven't since World War I. They are also less likely than autocracies to engage in mass killings.

It's not just that the United States and Russia are no longer picking fights (the odd Caucasian spat notwithstanding) -- they're frequently working out peacekeeping arrangements together in the United Nations. There was a threefold increase in peacekeeping operations in the decade after 1998, and a thirteenfold increase in multilateral sanctions regimes put in place between 1991 and 2008.

So, to return to Mr. Gorbachev, while there were long-term trends toward fewer people dying in war that predate his premiership, the period of glasnost and perestroika marked a dramatic acceleration of those trends. Even more than Ronald McDonald or Pascal Lamy, he's the person to thank for the current spate of global comity.

Foreign Policy, 28.02.2011