When people are having too few babies or too many, there's only so much that government can do.

Demographics crises may be the ultimate determinant of the fate of nations and the easiest to predict. In most cases, the population shift has already occured that dooms a country to slow or sudden decline.

We picked ten countries that stand out for extreme shifts in population and age, as well as countries facing unique situations due to political structure. For instance: even moderate shifts occuring in countries with large populations and economies, like the US, can be cataclysmic.

These ten countries are all developed or emergent markets, which is to say they do not include minor and undeveloped countries that are already locked into demographic chaos (see Niger, home to the world's highest birth rate).