My guess is that increasing life expectancy would retard (economic) growth, increasing the proportion of life that is healthy without changing life expectancy w

My guess is that increasing life expectancy would retard (economic) growth, increasing the proportion of life that is healthy without changing life expectancy would improve growth, "longevity" can refer to one or both of those, and if you do both at the same time it's hard to predict the effects. It seems like we'd be better off if we could evolve out of the need for growth, or at least the sort of growth that depends on limited external resources. That's tough to do because the most ravenous consumers tend to win out and be selected for, so even if you have a movement of people who are more efficient with resources (resources per unit of well-being), they'll tend to be shunted aside by the greediest segment of the population. More efficient bacteria can win out, but only if the inefficient greedy subset is made to be affected by the resource constraints. To address that, I'll make a modest proposal: find a valley somewhere and get all of the people most driven by external accumulation to move there. Make them compete with each other, creating ever more ostentatious and expensive ways for them to demonstrate their superiority. Create cultural barriers to moving anywhere else, except for people who are willing to let go of the rat race. Let nature run its course. Speed it up by seeding the population with a gender imbalance and cultural pressures to maintain or magnify that imbalance, so that breeding opportunities are limited. This will produce a lot of churn and waste in the process, so make sure there's a sandy substrate to allow for good drainage. That last part got a bit metaphorical, and would be even more so if I referred to this valley's sand by one of its principal components: silicon.