Title! I don’t get it. Isn’t my finger getting worn from just being used for too long? Or will it eventually get worse because of something else?
In: Biology
Being alive means everything in your body has to stay really well organized and coordinated. It’s the nature of things (see also: Second Law of Thermodynamics) that everything eventually becomes disorganized.
Biological aging is made of the following:
– Telomeres shorten over time. Telomeres are the end-caps or ‘shoelace tips’ protecting the DNA in your cells. The Telomeres are used up a little bit every time a cell divides. Once the telomere is worn away entirely, that cell can’t replicate anymore, and is essentially ‘dead’
– DNA damage buildup. The sun’s rays, viruses, and various chemicals damage your DNA. When your DNA gets too damaged, your cells cant replicate, or they replicate mutated and cause cancer or other diseases.
– Gene expression errors. Your cells arent reading your DNA correctly and you’re getting harmful mutations.
– Cells don’t die when they’re supposed to. As a side-effect of mutation or damage, sometimes cells dont submit to the natural maintenance cleanup and refuse to die. They keep using up the body’s nutrients, sitting around doing nothing.
– Energy production cellular marchinery malfunctions. Cells dont get enough food/energy/nutrients and die faster than they can be rebuilt.
– Inefficient cell communication. Due to damage accumulating over time, communication systems within the body break down, and cells can’t tell each other what they need. Like, your liver’s broken cell phone can’t tell your gut ‘hey we need more sugar down here!’ and never get that sugar delivery, and so cells die.
– Stem Cell exhaustion. Stem cells can turn into any other cells, and are important when healing damaged tissue. If you have no stem cells, your healing goes to shit and your little cuts never seal back up.
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All these things build up over time.
Due to accumulated damage, random mutations from sun radiation, and a breakdown of cellular processes, the body shows signs of ‘aging.’
And eventually your cells get so shitty at doing their job that a minor infection from a cut on your leg can’t be stopped, and it kills you. Or one of ten-thousand other ways ‘cells just not working’ can kill you.
yours cells stop dividing at some point. Once your last cells start dying and none can be remade to replace them, the body is essentially guaranteed to die as a result of one or more necessary organs simply ceasing to function. If that organ is the heart this death will may reported as cardiac arrest. If it’s the lungs then the report will cite respiratory failure.
Asking if the cause of death at that point is “old age” or “respiratory failure” is akin to asking at what point the Ship of Theseus stops being the original ship. There is no right or wrong answer, it’s just a semantic exercise.
Getting old is kind of like playing Jenga. A young body is like the Jenga tower at the start of the game, plenty of strength, can take a piece without much risk. But as you age the tower gets more and more unstable. At some point just a little nudge and it falls over.
Even without disease everyone will still age and become frail, without disease something will go wrong eventually and even if it didn’t what would the quality of life be.
Not one person *ever* has died of old age. Not your great grandma, not your childhood pet. In 100% of circumstances, something kills you. A disease. A small dose of radiation. A heart attack or stroke. The difference is that as you age, your body becomes less and less able to appropriately protect itself. Your cells don’t replicate as quick, your immune system can’t produce everything it needs to to protect you, and eventually… You succumb to something. Even people that “die peacefully in their sleep” are killed by something.
As your cells replicate, they accumulate errors in the genes. 99% of the errors don’t affect the cell – think, like, the genes to make insulin get corrupted, but in muscle cells. It doesn’t do anything. But, eventually, inevitably, the damaged genes code for something important, relevant to that cell’s job in your body. Or, the messed up genes lead to cancer. As all this damage accumulates, your organs can’t repair themselves effectively or function properly.
Additionally, because of the way DNA is shaped and the way that enzymes copy it, the very ends of the DNA cannot be copied. Think of a zipper, which needs a little tab to grab onto before it can start zipping. The enzymes are like that, and the “tab” that doesn’t get “zipped” can’t be copied, so it gets lost. Luckily, our DNA comes with pieces, called *telomeres*, which don’t code for anything and are there solely to be lost when the DNA gets replicated. Unfortunately, we have a limited number of those. Cells that replicate very often may run out of telomeres, and then important genes on the ends do get lost.
One example may be the code for collagen, which helps make skin stretchy. Skin cells have to replicate a lot, so they run out of telomeres quickly. Collagen is one of the first genes that gets lost, which is why your skin stops being as stretchy and gets wrinkly as you age.
*Officially*, really, the cause of death is some kind of organ failure, probably connected to cancer.
Your body is like a giant photocopier. All of your cells copy themselves, and then die. Then the new copies copy *themselves* and die. The cycle repeats for your entire life.
If you’ve ever copied a copy, you know that you lose a little bit of clarity every time. The image gets fainter and has more blurry, and there’s a chance of errors (like slightly tilting a page, or a piece of lint that snuck in) that just get repeated down the line. Cells are just like that. As they copy, they lose a little bit of their usefulness. Old bodies are like faint, worn out copies of themselves. When poor copies of things like cardiac muscle, arteries, or organs hit a certain point, the cells just cannot function well enough to keep the organism (you) alive.
People who die of “old age” usually die of heart failure or aneurysm. Even if there was zero viruses, bacteria, or diseases, we would still be old. Our copies would still fail. It’s by design.
Nobody dies of just being old, just like no car stops working just cause it’s old. A car stops working because some critical system goes out, which becomes more and more likely to happen as those parts get older and more worn.
Same with the body. Some critical system finally wears out and stops functioning properly.
All of those individual parts going out has its own name and its own diagnosis as a disease, so technically you are dying of the disease, but the prevalence and severity of these conditions increases naturally as your “parts” get more and more worn out.
Id just add to the good explanations on dying of old age what i think about the wear on your body. There is definitely wear on your body but most parts of your body the experience wear like your finger arent necessary to stay alive. So maybe could be the case that you live til 200 without dying from a disease and real luck with your cells. But the wear on your body will mean that you wont be able to move and such.
Here’s the thing. Disease is a very broad term, and can refer to any disorder of the body not caused by external injury. So yes, our bodies do naturally wear out over time, but the effects of that wear would count as diseases.
That being said, the age related diseases we deal with today do not necessarily represent the theoretical limit of human age. Scientists believe that if these diseases could be cured, our bodies could last much longer before more advanced age related diseases would finally kill us.
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