It's no wonder that almost no one gets old enough to die a natural death anymore. Instead they'll die from self-made diseases like heart attacks and cancer.
So my understanding, and correct me if I'm wrong here, is that if you live long enough you are guaranteed to get cancer. Cancer mainly comes from damaged DNA, and that damage can happen from either external or internal sources. As you age the protein strands protecting your chromosomes (telomeres) deteriorates and damage starts to form. The "programmed death" in your genetic coding. The closest thing to 'natural death' I've ever heard of. Live long enough and you will die of cancer.
The idea of "Natural death" back once upon a time used to be the gatekeepers of their time, things they may not have understood the cause or the prevention of. Things modern medicine and science has significantly reduced the likelihood of or have directly identified the cause of. Yes we die of self made illnesses and "preventable deaths" more now because of 2 main reasons. One we know through science what attributes to those diseases and how to prevent them. Two, those previous gatekeepers (whatever is identified as leading causes back whenever) have been removed and now we are faced with a new set of gatekeepers. You remove those and a new one will take it's place. That's actually the concept I'm painting here. The graph distribution below will probably always look very similar regardless of what is in each category.
Major reasons for death today being heart disease and stroke. Say you ate more healthy and eliminate dietary causes, lung disease and cancer become the leaders potentially, possibly preventable if you reduce air pollutions and stop smoking. Say you prevented those as well, lets say Alzheimer's now becomes the leading cause of death worldwide. Some say that's preventable, now it comes down to infections and car accidents. You can keep going down the list. Something is eventually going to be the gate keeper, someone is going to identify the cause and push to solve that problem and criticize those that are doing the things that could prevent that type of death. The average life expectancy increases across the board as it has since we started recording reasons for death throughout history and we keep pushing to the next preventable death. I can imagine once upon a time, a similar conversation was being had about how not to go out of the trees because eaten by lions was the leading preventable death of it's time.
There is no 'dieing of old age'... that's not scientific, science says you died of something on the list of major causes, science also says that reason is possibly preventable or much effort is in to identify the cause and find a way of preventing it. 'Natural death' is not on the list, death by 'old age' doesn't exist.
en.wikipedia.org