World's history (part 14): Contemporary history[edit] Main article:Contemporary history 1900–1945[edit] Main article:20th century Further information:Interwar period,Roaring Twenties, andGreat Depression World War Istatictrench warfare, western Europe History's only use ofnuclear weaponsin war— Hiroshima and Nagasaki, 1945 The 20th century[148][149][150]opened withEuropeat an apex of wealth and power, and with much of the world under its direct colonialcontrol or its indirect domination.[151]Much of the rest of the world was influenced by heavily Europeanized nations: the United Statesand Japan.[152]As the century unfolded, however, the global system dominated by rival powers was subjected to severe strains, and ultimately yielded to a more fluid structure of independent nations organized on Western models. This transformation wascatalysedbywarsof unparalleled scope and devastation.World War I [153]destroyed many of Europe's empires and monarchies, and weakenedBritainand France.[154]In its aftermath, powerful ideologies arose. TheRussian Revolution[155][156][157]of 1917 created the first communiststate, while the 1920s and 1930s sawmilitaristicfascist dictatorships gain control inItaly,Germany,Spainand elsewhere.[158] Ongoing national rivalries, exacerbated by the economic turmoil of theGreat Depression, helped precipitate World War II.[159][160]ThemilitaristicdictatorshipsofEuropeandJapan pursued an ultimately doomed course ofimperialistexpansionism. Their defeat opened the way for the advance of communismintoCentral Europe,Yugoslavia,Bulgaria,Romania,Albania, China,North VietnamandNorth Korea. 1945–2000[edit] Main article:20th century AfterWorld War IIended in 1945, theUnited Nationswas founded in the hope of allaying conflicts among nations and preventing future wars. [161][162]The war had, however, left two nations, the United States[163]and theSoviet Union, with principal power to guide international affairs. [164]Each was suspicious of the other and feared a global spread of the other's political-economic model. This led to the Cold War, a forty-five year stand-off between the United States, the Soviet Union, and their respective allies. With the development of nuclear weapons[165]and the subsequent arms race, all of humanity were put at risk ofnuclear warbetween the two superpowers. [166]Such warbeing viewed as impractical,proxy warswere instead waged, at the expense of non-nuclear-armed Third Worldcountries. TheCold Warlasted to the 1990s, when the Soviet Union's communist system began to collapse, unable to compete economically with the United States and western Europe; the Soviets' Central European"satellites"reasserted their national sovereignty, and in 1991 the Soviet Unionitselfdisintegrated.[167][168][169]The United States for the time being was left as the"sole remaining superpower". [170][171][172] In the early postwar decades, theAfricanandAsiancolonies of the Belgian, British, Dutch, French and other west European empires won their formal independence. [173][174]These nations faced challenges in the form ofneocolonialism, poverty, illiteracy andendemictropical diseases .[175][176] ManyWesternandCentral Europeannations gradually formed a political and economic community, theEuropean Union, which expanded eastward to include former Soviet satellites. [177][178][179][180] LastMoonlanding —Apollo 17(1972) The 20th century saw explosive progress inscienceandtechnology, and increasedlife expectancy andstandard of livingfor much of humanity. As the developed world shifted from a coal-based to apetroleum-based economy, new transport technologies, along with the dawn of the Information Age,[181]led to increasedglobalization.[182][183][184]Space explorationreached throughout the solar system. The structure ofDNA, the template oflife, was discovered, [185][186][187]and thehuman genomewas sequenced, a major milestone in the understanding of human biologyand the treatment ofdisease.[188][189][190][191][192]Global literacyrates continued to rise, and the percentage of the world'slaborpool needed to produce humankind'sfoodsupply continued to drop. The technologies of sound recordings, motion pictures, and radio and television broadcasting produced a means for rapid dissemination of information and entertainment. Then, in the last decade of the twentieth century, a rapid increase took place in the use of computers, including personal ones. A global communication network emerged in theInternet. The century saw several man-made global threats emerge or become more serious or widely recognized, including nuclear proliferation,global climate change,[193][194]deforestation,overpopulation, near-Earth asteroids and comets,[195]and the dwindling of globalnatural resources(particularlyfossil fuels).[196]