Looking at society as a whole, there's not much to be gained by increasing lifespan. There's no shortage of people being born. They come up to speed quickly to

Looking at society as a whole, there's not much to be gained by increasing lifespan. There's no shortage of people being born. They come up to speed quickly to be able to do useful things (20 years or so). There are a few people doing great work even in old age, who couldn't easily be replaced by somebody younger, but I'd say they are an exception. There's no reason to think those particular people would be chosen for life extension first.