By Yasmin Tayag for Inverse Science - There’s a common thread tying together the most disruptive revolutions of human history, and it has some scientists worried about the United States. In those revolutions, conflict largely boiled down to pervasive economic inequality. On Wednesday, a study in Nature, showing how and when those first divisions between rich and poor began, suggests not only that history has always repeated itself but also that it’s bound to do so again — and perhaps sooner than we think. In the largest study of its kind, a team of scientists from Washington State University and 13 other institutions examined the factors leading to economic inequality throughout all of human history and noticed some worrying trends. Using a well-established score of inequality called the Gini coefficient, which gives perfect, egalitarian societies a score of 0 and high-inequality societies a 1, they showed that civilization tends to move toward inequality as some people gain the means to make others relatively poor — and employ it. Coupled with what researchers already know about inequality leading to social instability, the study does not bode well for the state of the world today. “We could be concerned in the United States, that if Ginis get too high, we could be inviting revolution, or we could be inviting state collapse. There’s only a few things that are going to decrease our Ginis dramatically,” said Tim Kohler, Ph.D., the study’s lead author and a professor of archaeology and evolutionary anthropology in a statement.