People are living longer than ever before. Today, the majority worldwide can safely see themselves living into their sixties, according to the World Health Organization.

The country where people live longest -- measured as life expectancy at age 60 -- is Japan.

Coming a close second are a string of countries spanning the Mediterranean and East Asia, as well as countries with strong economies and healthcare systems.

By measuring life expectancy at age 60, factors such as childhood illness and issues earlier in life are discounted and longevity is more related to an individual's lifestyle and environment during older age.

We asked a selection of aging experts why these countries are outliving the rest -- and what secrets they hold to longer life.