Age and power: Do older leaders govern responsibly?
The retirement of Pope Benedict XVI has re-opened the debate about whether older people have sufficient physical and mental strength to responsibly hold down positions of power.
In the professional world many people retire completely by the age of 70 - but around the world there are currently several older leaders still in power.
Britain's Queen Elizabeth II is 86 and has reigned since 1952, while 88-year-old King Abdullah of Saudi Arabia was named by Forbes as one of the world's top 10 most influential leaders in 2012. India's Prime Minister Manmohan Singh is 80 years of age and Robert Mugabe, 89, has been in power in Zimbabwe for more than 30 years.
The BBC's Zeinab Badawi discussed the issue with Winston Churchill's grand-daughter Emma Soames and Gautam Mukunda from Harvard Business School.