India is about to overtake China as the most populous country, but as birthrates fall we’re facing life in a greyer world. Are we ready for the physical, political and financial challenges ahead?

In Japan even criminals are getting old. In the country’s notorious yakuza crime syndicates, more than half of members are now over 50, according to the national police agency.

Veterans who have passed 70 outnumber those in their 20s by two to one, even though younger men are the groups’ traditional source of “muscle”.