And for this, more than 16 million men went to their slaughter, many of them in cruel and creative ways. In trenches that stretched an unbroken 475 miles from the North Sea to the Swiss border, the Germans constructed walls using corpses, so that French troops who captured a trench hung canteens from protruding ankles. Along the Somme River, in northern France, more than 1 million men were killed or wounded in 1916 for an Allied advance of seven miles. Poisonous gas filled a quarter of all the artillery shells fired on the western front in 1918. More than a third of German males born between 1892 and 1895 died in the course of the war. The killing spread to civilians in England and France attacked by German zeppelins. War was no longer noble, even as some of the men who fought it were noble beyond compare.

It was a sad, pointless war, for which we’re still paying a price. A hard-hearted peace treaty and a ravaged economy produced a “lost generation” of young Germans and led directly to the rise of Hitler and an even uglier worldwide conflagration. The secret Sykes-Picot Agreement reached by Britain and France in 1916 drew arbitrary boundary lines across the postwar Middle East—around Iraq, for instance—that are returning deadly dividends to this day. The toppling of the Russian monarchy and the collapse of the Austro-Hungarian Empire created a balkanized Europe that, as recently as the downing of Malaysia Airlines Flight 17 over strife-torn Ukraine, pains us still. The world was a nastier place after the war than before it.

All wars tell us something about the basest regions of human nature, the First World War (caustically named in 1918 by an English journalist who thought it would not be the last) more than most. About the nature of covetousness, the perils of insecurity, the ease of losing human control over human events.

So, has our species evolved? The counterevidence is distressingly abundant. The Nazis’ ovens in World War II. Stalin’s gulags. The genocides in Cambodia and Rwanda. The return to seventh-century standards of thought and behavior incited by the Iranian revolution of 1979 and practiced by jihadists across the Middle East.

Indeed, evidence is slim that we’ve grown wiser since the war intended to end all wars did nothing of the sort. Still, if it’s any consolation amid the tragedies and disorder of today’s world, Homo sapiens have been way stupider in the past than they are right now.

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