Why is there not an age for retirement from politics? Hunger for power is something I can understand when someone is in his/her 40s or 50s. When one steps into 60s, he/she can't just keep up with the pace at which events happen in the world. Brain being just another biological machine, cannot process information into knowledge & that knowledge into wisdom effectively when its been around for 60 years. And not being abreast with the developments - not just politically, but economically, technologically & socially, the best public service a leader can perform is to retire and let the relatively younger folks take over.
Experience is of no use after a threshold. In fact, too much experience in politics is detrimental as one loses the vision to steer the statre. Jyoti Basu (W Bengal), Karunanidhi (TN), Karunakaran (Kerala), Fidel Castro (Cuba), Suharto (Indonesia).... This is not to say that they did/doing a bad job in their old age; but a sad realization that things could have been better if only someone else had been at the helm. As mentioned earlier, when one needs an assistant to help him stand up (literally) it's quite difficult to understand their love for a chair.
That funny & sad cartoon was published in the Time magazine when Fidel handed over the reins to his brother Raul Castro, 76.