Nummy is right; he's not "over 90", he's 85 (86 this coming May 8th).
It's a fact of life that as one gets older one's voice, gait and demeanour sometimes undergo some changes. One thing that sometimes undergoes changes as well, to a greater or lesser degree, is one’s mind. Sir David Attenborough’s mind most certainly has not suffered any untoward changes. He is still as informative and entertaining as he was 30 years ago. I’ve just watched “Darwin’s Tree of Life” and it was well put together, very interesting and superbly presented.
Quite who Jemisa has in mind who might have similar talent, skills and knowledge as Sir David and who is currently being denied their “opertunity”, it is hard to imagine.