The author is somewhat confusing aging and dying. Aging is a mechanism. It is there for (probably) many reasons. One of them is to protect against cancer, and therefore from dying. You either age or you get cancer.
"Aging" might have evolved in part because of cancer, but that does not mean that aging is the best solution to cancer. It's just a method of dealing with it, which might be totally subpar. Evolution never leads to best-case scenario, it leads to good-enough scenario. Saying "either you age or get cancer" is just... not correct.
If we find a way to not age and not get cancer, then we have (presumably) evolved.
>That is not true. It could lead to the most optimal solution.
There is no such thing as "the most optimal solution". Optimality is a human imposition on the world. Fitness functions do not actually exist, they are merely a way for us to conceive of the operation of selection. Evolution is not performing gradient descent.
This sort of adaptivism has got to go. First of all, nothing is there for any reason; it just is. Evolution is an ad hoc process where things happen because they need to, and they happen based on expediency. There are many facets of life that escape adaptive constraint - selection has a limited reach.
This comment supposes that aging protects cells against cancer; I think this presumption is based on the antitumor properties of telomeres, which impose the 'Hayflick limit' on cellular division.
It is presumed by humans that this mechanism may have some adaptive role in tumor suppression. However: this is not why it appeared (all eukaryotes have telomeres, even unicellular ones), so any antitumor properties are an ancillary benefit.
It is incorrect to assume it impute reason to evolution. It seems highly likely that aging rests close to the border of selective influence, and it is highly presumptive to imagine it is governed by consequence.
This is not a presumption I made. This is believed by many scientists. Telomeres are just part of the story. There are many other reasons[1,2,3]. The third link is not a paper so very readable.
The cell has many ways to combat oncogenesis and when these protections fail, it tries to go into senescence (SIGTERM) or die(SIGKILL).
Nanobots that would replace damaged cells with new non-cancerous ones are not yet here.
I'm a cancer biologist, so I appreciate the relation to oncogenesis. But you said "It is there for (probably) many reasons". This is what I am contending; aging is simply there, because that is what happened. 'Reason' is a judgment we apply, and it's important to appreciate that much of what exists is not driven by anything we might call "reason". I do not believe that the collection of phenomenon we call "aging" is uniformly the product of adaptive consequence. Notably, we die in part because evolution simply doesn't care, or isn't able, to keep us alive indefinitely.
It's important to note that aging is not so much a mechanism to protect against cancer as it is a method to avoid cancer (that is, by dying before cancer develops).
The cell dies or stops working as effectively as before and is potentially replaced by other cells, but the organism lives. So overall, the cell's DNA is more likely to be transmitted.
If the cell lived (selfishly), it could take down the whole organism with it and not reproduce.
They are much the same thing in many discussions of aging. The generally agreed upon definition of aging in the geroscience community is that it is an increase in risk of death due to intrinsic causes. You are more aged if you have a higher risk of death, and you are aging if your risk of death due to intrinsic causes is higher today than it was yesterday.
Then we can get into primary aging (think of the SENS list of damage, internal mechanisms like mitochondrial damage and cross-link deposition) versus secondary aging (think of smoking and getting fat, things that increase the pace of damage accumulation), and further complexities after that. But the core definition of aging is very simple, and it is all about dying.
Coming from the biochem community (I'm not a scientist and was just a tech there + grad school classes), aging in the labs I worked in was seen as more of a mechanism. Sure, it leads to deterioration of cellular function which inevitably leads to death.
However, aging!=dying since aging can protect the whole organism (as opposed to individual cells) from dying and some would argue that it is there primarily to protect the organism from dying from cancer and for healthy reproduction.
What?! Please don't call cell senescence "aging". Our cells do destroy themselves and replenish from stem cells but the accumulated damage called "aging" causes cancer.
If you age, you get cancer, eventually. Sometimes some other pathology gets you first but everyone is afflicted with every "aging disease" but we seem to only care about which one kills you first.
Senescence (/sɪˈnɛsəns/) (from Latin: senescere, meaning "to grow old," from senex) or biological aging (also spelled biological ageing).
One of the reasons cells age is to not get cancer. The cells that age can still get cancer! And probably more likely to get cancer than young cells. But less likely than if they didn't go into senescence at all.
