It's well known by now that income and wealth inequality in most rich countries, especially the United States, have soared in recent decades and, tragically, worsened even more since the Great Recession. But what about the rest of the world? New research by a World Bank economist named Branko Milanovic, along with other scholars, points the way to some answers. Overall equality across humanity, considered as individuals, has improved very little. So while nations in Asia, the Middle East and Latin America, as a whole, might be catching up with the West, the poor everywhere are left behind, even in places like China where they've benefited somewhat from rising living standards. From 1988 to 2008, Mr. Milanovic found, people in the world's top 1 percent saw their incomes increase by 60 percent, while those in the bottom 5 percent had no change in their income. And while median incomes have greatly improved in recent decades, there are still enormous imbalances: 8 percent of humanity takes home 50 percent of global income; the top 1 percent alone takes home 15 percent. The United States provides a particularly grim example for the world. And because, in so many ways, America often leads the world," if others follow America's example, it does not portend well for the future. Last year, the top 1 percent of Americans took home 22 percent of the nation's income; the top 0.1 percent, 11 percent. Ninety-five percent of all income gains since 2009 have gone to the top 1 percent.