The meaning of death and aging from a biological point of view

I have listened to a lecture on line regarding the meaning of death and aging from the standpoint of biology by Prof. Takehiko Kobayashi of Tokyo University. To be short, death is a result of destruction of DNA. It will work for variation and evolution. We should die for the generation ahead.

It was more interesting to me on the meaning of aging. 

Old age, defined by post reproductive age, is unique to human being. Most mammalians except for human being and few exceptions would die as soon as they finish reproducng the next generation. For human being, old age lasts long or decades. The reason of existence of old age is as follows; human being gets born without "fur" on the surface and babies won't live by themselves for the first 3 years. The new borns require "grandma" caring for them. And when we get old, we could be free from egotism and could behave in altruitism. It is a widsome of "grandpa". Whether male or female, we could live for the next generation. Proessor Kobayashi says the meaning of old age resides in that altruitism. 

Some old people, expecially those in political power, behave the opposite to this nature of the elderly. They pursue endlessly own power and fortune. Some of them behave like a saviour in the world as if a religious icon. They seem to believe their lives are endless. They are often backed up by some kind of cult. People in the cult support enthusiastically such a dictating politician as if he was a saviour to the world. The supporters could not understand  what their behaviour leads them as well as the other people. Such dictating leaders lead to collapse and perish of the world. It may be due to loss of "grandma" as well as "grandpa" characteristics in humankind.