( CNN ) -- `` War ! What is it good for ? '' sings Edwin Starr in his 1970 song , before giving an unambiguous answer : `` absolutely nothing . '' History , archaeology , and anthropology , however , suggest that the story is not so simple . In the Stone Age , humans were a rough lot . When people 10,000 years ago disagreed , they usually solved their arguments without violence ; but when they did decide to use force , they faced far fewer constraints than the citizens of functioning modern states . Violence was normally on a small scale , in homicides , vendettas , and raids , but because populations were also tiny , the steady drip of killing took an appalling toll . By many estimates , 10 to 20 % of Stone Age humans died at other people 's hands . If we fast-forward to the 20th century , we see a stunning contrast . The century suffered world wars , genocides , and nuclear attacks , not to mention civil strife , riots , and murders . Altogether , we killed a staggering 100-200 million of our own kind . But between 1900 and 2000 , roughly 10 billion lives were lived -- meaning that just 1-2 % of the world 's population died violently . So if you were lucky enough to be born in the 20th century , your risk of dying violently was just one-tenth of that in the Stone Age ; and since 2000 , the United Nations tells us , the risk of violent death has fallen even further , to 0.7 % . These are astonishing statistics , but the explanation is more astonishing still . In perhaps the greatest paradox in history , what made the world safer was war itself . What happened , it seems , is that starting about 10,000 years ago , the winners of wars began incorporating the losers into larger societies . The victors then found that the only way to make these larger societies work was by developing stronger governments ; and one of the first things these governments had to do , if they wanted to stay in power , was suppress violence among their subjects . The men who ran these governments cracked down on killing not because they were saints , but because well-behaved subjects were easier to govern and tax than angry , murderous ones . States that suppressed violence within their borders tended to grow ; those that did not , tended to fail . War is surely the worst possible way to create larger , more peaceful societies , but the depressing truth is that it seems to be pretty much the only way people have found . If Rome could have been built without killing millions of Gauls and Greeks , or the USA without killing millions of Native Americans -- in these and countless other cases , if conflicts could have been resolved by reason instead of force , the world would have reaped the benefits without paying such costs . But that did not happen . The reality is that people hardly ever give up their freedoms , including their freedom to kill and impoverish each other , unless forced to do so , and virtually the only force strong enough to scare people straight has been strong government . Back in the 1600s the philosopher Thomas Hobbes nicknamed this `` Leviathan , '' after the terrifying monster of the Old Testament . The process of making Leviathan was not pretty . Whether it was the Romans in Britain or the British in India , pacification could be just as bloody as the savagery it stamped out . Nor were all governments equally good Leviathans . Democracies , whatever their other faults , tend to value life more than dictatorships . Nor did Leviathan always work the same way . In ancient times , the only way to run large , peaceful societies was by incorporating the conquered into empires , but in the last 200 years , the greatest powers -- Britain in the 1800s , the U.S. since the late 1900s -- have worked best by leaving other countries formally independent while incorporating them into globalized economies . Nor , finally , was the making of Leviathan smooth . Some wars killed people without creating bigger , safer societies ; some even broke such societies down . But across 10,000 years , enough wars did create these bigger , better-governed groups that rates of violent death fell by 90 % . The 21st-century world does not have a global government enforcing peace , and far from producing such a government , another great-power war could potentially destroy humanity altogether . The world does , however , have a single great power -- the United States -- capable of acting as a globocop , deterring other governments from using force . The United Nations , European Union , the peace movement , and soft power generally have all done much to make the world a safer place since 1945 , but the lesson of history is clear . At the end of the day , in answer to the song 's question -- what has war been good for ? -- is that war created Leviathan , and Leviathan made the world safer . Like it or not , the ultimate guarantee of peace is the order the United States has created .
Since 10,000 years ago , Stone Age says the risk of violent death has fallen to 10 to 20 % . In perhaps greatest paradox in history , what 's made the world safer is war itself , Morris says . War seems to be only way people have found to create peaceful societies , he argues . Ian Morris : World has single great power -- USA -- capable of deterring governments from using force .