Old people generally mellow with age. They are less likely to be confrontational and more likely to reflect on the world. They are also more likely to have families they care about and thus something to lose.

That goes for terrorists also, according to a new theory by Mark Haas of Duquesne University in the latest Public Policy & Aging Report (PP&AR). It says several hotbed areas in the world that offer the motive and opportunity for political violence are due to stabilize by the year 2030 because current young people will be old.

Countries such as Iraq, Pakistan, and Saudi Arabia are currently experiencing "youth bulges" (a disproportionately high number of young people in a society) along with high rates of unemployment.

Haas argues that this has created many individuals with strong grievances against current political conditions and little stake in society. He then cites research showing that population aging and the diminishment of youth bulges - which these countries are due to experience in the next 22 years - has been a source of political stability and economic development in many other regions.

The same aging trend is beginning to affect even the most powerful states in the world, including Britain, China, France, Germany, Japan, Russia, and the United States.

For example, Russia's working-age population (ages 15 to 64) is expected to shrink 34 percent by 2050. The country's population is already decreasing by 700,000 people per year. Also by 2050, China's median age is predicted to be nearly 45. Given this fact, their government will be faced with a difficult choice: allow growing levels of poverty within an exploding elderly population, or provide the resources necessary to combat this problem by diverting funds from military spending.

The United States is not immune to the problems of global aging, but it does stand to fare better than many of its rivals. In 2050, this country's median age will be the lowest of any of the great powers. And by the same year, the working-age population in the U.S. is expected to increase by 31 percent. Additionally, the United States has a relatively well-funded pension system.

Under the title "Global Aging: Rise and Consequences," this installment of PP&AR also contains three other articles outlining current research about aging societies. Carl Haub of the Population Reference Bureau speaks of "the demographic divide" in reviewing different mortality and fertility trends around the world. Harvard's David Bloom and David Canning focus their attention on the economic implications of global aging. And Adele Hayutin of the Stanford Center on Longevity pays particular attention to population aging in the less-developed world.