"Funny thing is historically speaking 40 is a lot closer to the useful human lifespan than 100." That isn't really true. Life expectancy was historically drive

"Funny thing is historically speaking 40 is a lot closer to the useful human lifespan than 100." That isn't really true. Life expectancy was historically driven down by high infant mortality and lack of medicine. The meaningful human lifespan has been in the 70s for the majority of history. (Lifespan is different from life expectancy) "So this strong belief of yours is really driven by advancements in society and healthcare over the last few decades." Who says it's a strong belief? "Why do you think that won't change drastically another few decades from now?" Because there's no real evidence to support that. Life expectancy hasn't gone up drastically over the past 50 years. Rates of chronic illnesses, including things like dementia, have gone up drastically. So even if people are living a couple years longer, they're generally sicker and it's costing more. Even if medicine makes drastic improvements, 100 is still a lofty goal. I'd be fine making it only 80 too. I'm actually skeptical that will even happen. What I do know is that I don't want it to take more than 100 years.