What would a civilisation be like whose people have predetermined lifespans?
Imagine a civilisation resembling our own, except that the "people" there have predetermined lifespans. That is, in the absence of unnatural death (deaths caused by external forces like car accident, gun, fire, water, hunger, thirst etc.), everybody knows exactly how long they are going to live (say 80 years. Note: everybody has identical lifespans. But other organisms than "human" don't have such a characteristic.) since they are born. Let's also assume these people never develop fatal diseases (cancer, HIV etc.), so the only way to die unnaturally is by violent external forces. My question is, in what ways will this civilisation drastically differ from ours?
To name a few, first I think their medical knowledge will remain at a very elementary level since they don't have to deal with tons of fatal diseases that we have to face today. Most likely they will only develop surgical medicine since external wounds are basically the only threats to their life. Second, I think they will have designated places for people to go there and wait for their end in a calm and perhaps even carefree manner. 113
There will be no fear of death since death is SO predictable that they are likely to just view it as a trivial phase of life or simply the gate to their next life cycle. Of course there are many other things I want to explore like how such complete predictability of death will shape their psychological, religional, economical, and political landscapes?
Any compelling story is much welcome. Thanks!
EDIT
1. sorry that there's been some confusion on if everybody has the same lifespan: yes, everybody is predetermined to live the same amount of time at birth.
2. @JBH raised a good point in the comments about whether their organs would "age" or decay during their lifespan, which I didn't think about when writing this post. Let's assume that in this world the elder are also generally less physically agile and less mentally sharp than the younger. You may assume the older have tooth decay at advanced ages, etc. They may also be exposed to the risk of breaking their bones/suffering wounds etc, but they do not suffer a higher risk of death from such stuff than the younger. For example, the probability a wound would kill an elder "person" is the same as the probability the same would would kill a younger "person". 759