That is interesting.
But I wonder how the model would be affected by, say, the mass availability of a significant longevity increase, brought about by some sort of medical breakthrough?
But I wonder how the model would be affected by, say, the mass availability of a significant longevity increase, brought about by some sort of medical breakthrough?
They mostly are actually. Barring the occasional exception there is a definite 20-40 or so age band where most females that have children will have them. This is in part because of society and custom and in part for very valid medical reasons, the chances of children having birth defects go up quite fast past the age of 35.
Medical breakthroughs tend to affect the latter rather than the former more, though the fact that people live longer has an effect on the age at which they start with having children. In my grandparents generation it wasn't rare for 19 year olds to be married and to have their first child on the way, my parents generation had their children when approaching 30 (on average), and the present day generation has their first child later still. There is some correlation here with education levels and of course from country to country there are still huge differences but overall those seem to be the trends.
So a significant longevity increase brought about by a medical breakthrough will likely cause people to have their children at an even later age (with all the associated risks, possibly resulting in much more screening), somewhat offsetting the effect of those people themselves being alive for longer.
Social security would be a real problem, especially if the time that people could work productively would not increase at the same rate as the longevity.
- If it's "stay old longer" then yeah, that's a problem (most of our present advances are this since they don't address ageing, just save people from its consequences).
- If it's "stay young longer (or indefinitely)" that will change a lot of assumptions. But it might also make people put off children until really late, like, "if you're less than 100 why are you even considering being a parent?"
Actual therapies would go in and undo the damage, not stop it accumulating, but clean the existing damage down to a level where ageing symptoms would be reset back by decades. And could be repeated, leading to indefinite lifespans.
The downvotes to my comment above amused me, there are apparently people in denial here. :)
Google: the SENS research foundation.