THE distribution of wealth lies at the heart of political economics. Nations and empires have risen and fallen, and millions have died, as a result of humanity’s struggle to decide how (or whether) to divide wealth.

But for all that, the level of wealth inequality has remained remarkably consistent over the last 2,000 years, according to a recent study by Branko Milanovic, a researcher with the World Bank, and two economics professors, Peter H. Lindert of the University of California, Davis, and Jeffrey G. Williamson of Harvard University (economics.harvard.edu).

While “human civilization has advanced by leaps and bounds over the past two millennia, income inequality has stayed relatively the same,” Zubin Jelveh of Portfolio.com wrote about the study.

The “inequality extraction ratio” is basically the share of the wealth difference taken by “elites.” Since the United States is the wealthiest nation in history, the potential for elites taking a bigger share of the wealth (without allowing mass starvation) is greater. But they have not done so. “Thus,” the researchers write, “the social consequences of increased inequality may not entail as much relative impoverishment, or as much perceived injustice, as might appear.”