[rwissmann]

"therefore there is selection pressure for longer (reproductive) life spans"

this is too simplistic. there is also selection pressure for shorter generational cycles, leading to faster evolution. keeping older generations around would consume extra resources.

[Houshalter]

You are anthropomorphising evolution. Natural selection only favors individuals, not the species as a whole. Plus it's not clear if that would actually be a benefit. An organism which has survived and reproduced for hundreds of years probably has very fit genes.