Respecting the elders to live longer

According to a talk on Buddhism that I listened to, to live longer one must not be rude to the elders. On the other hand, if we always respect the elders we can have a longer life span. Of course, we must refrain from killing too or else the former action will be futile.

Why do we respect the elders? Well, for one thing they are knowledgeable, for another by showing respect to them, they might help us tide over our difficulties by offering good suggestions. It is also a virtue to respect the elders.