"Before the G-7 meeting in Japan, several member countries indicated they understood that their individual and collective policy stances needed to evolve."
The word evolution describes change that is the result of an organic or natural reaction to environmental factors over a long period of time. Meaning no one controls such a process but it's purely "formed" by the environment.
So this is sometimes used as a really polite or face-saving way of saying "change" without placing blame on anyone.
To be transformed from one form into another by a process of gradual modification, esp. from a more rudimentary to a more highly organized condition - Oxford English Dictionary
The G-7 member countries are saying that their current policies in relation to their central banks lack the depth and maturity that is needed for the job and that improving them will be a process of many steps - the article gives examples of the things that need to be done.
So, rather than a single, radical change that solves everything they are proposing that the policies grow in the same way that an organism evolves to meet the challenges and opportunities of its environment
The company has evolved over time from a simple telephone company to a telephone company, Internet provider and communications specialist.
The evolution of the thumb allowed human beings to become tool-makers.
The people of Venus have evolved over time into super-humans who are capable of breathing under water, and communicating through thought waves. from the source: http://www.use-in-a-sentence.com/english-words/academic-words-english/evolution.htm