I would consider cancer a sort of cellular "evolution". The cell starts rapidly producing, which is advantageous considering its environment where resources are generally abundant. It results in the eventual death of the human, but on a cellular level it has become the dominant cell. The problem is that the cellular evolution isn't aware of how it affects the organism as a whole.

This is something I've been wondering about myself. If you think about it, the cancer cells are, indeed, the dominant and healthy ones, even though they cause eventually the collapse of the organ/organism. Does this mean that part of the problem is in the other cells, who can't absorb nutritious resources and multily themselves, and let the cancerous ones multiply uncontrollably?

[quote name='Khaiy' timestamp='1296773469' post='4769229'] Finally, evolutionary pressures are unlikely to operate on the cellular scale of an organism. The success of a cell's ability to reproduce has little to do with the cell itself. The organism that contains the cell provides ample resources for reproduction, as well as protection from "predators", and so on. And no matter how well or poorly cells perform, the death of the organism results in the death of all cells. This also ends the lineage of those cells forever, with the exception of organism-level reproduction, which has several obstacles to the level of fine-tuning described above.

I am aware that it doesn't happen as it stands now (probably in large part due to our relatively short lifespans among other things). I was mostly talking about finding ways to perhaps trigger our cells to "evolve" in desirable ways so that as you get older your body performs and repairs itself better. Trigger isn't exactly the best word I'm looking for I just can't think of the right one atm. This is all pie in the sky wishful thinking, but I could see a world where that would be something achievable. I would consider cancer a sort of cellular "evolution". The cell starts rapidly producing, which is advantageous considering its environment where resources are generally abundant. It results in the eventual death of the human, but on a cellular level it has become the dominant cell. The problem is that the cellular evolution isn't aware of how it affects the organism as a whole. [/quote]

I think I see your point more clearly now. But I'm a little bit confused about the desirable "new" traits you're talking about in cells, the ones that increase performance and repair in older people. The human body is already really good at those things, and the issue with aging is that those abilities degrade, in response to mutation and shortening of the genome. Sure, you could repair DNA like the enzyme telomerase does (which replaces the portions of telomeres cut off during DNA copying), and then potentially replace the damaged portions of DNA such that they performed as they did at their peak, but the cells aren't doing anything different than what they did before the degradation occurred.

It sounds to me like your interest is in repairing the degradation-- but it would likely be easier all around to prevent the degradation before it affects functionality. I think that that's what the TED speaker above was talking about. An interesting side note to this is that telomerase is produced by human cells, but only at the stem cell stage. The portion of DNA that codes for that enzyme is methylated (prevented from ever being transcribed again) very early in an organism's development.

[quote name='way2lazy2care' timestamp='1296833313' post='4769562'] I would consider cancer a sort of cellular "evolution". The cell starts rapidly producing, which is advantageous considering its environment where resources are generally abundant. It results in the eventual death of the human, but on a cellular level it has become the dominant cell. The problem is that the cellular evolution isn't aware of how it affects the organism as a whole.

This is something I've been wondering about myself. If you think about it, the cancer cells are, indeed, the dominant and healthy ones, even though they cause eventually the collapse of the organ/organism. Does this mean that part of the problem is in the other cells, who can't absorb nutritious resources and multily themselves, and let the cancerous ones multiply uncontrollably? [/quote]

If you think of it that way, the problem is in the immune system of the organism. But an organism is not an ecosystem in the sense that other environments are, where individuals compete for resources to gain reproductive advantage. An organism is a large and complex set of symbiotic relationships, and if a given cell goes rogue it would be up to processes directed at the organismal level to deal with it, not any direct cell-to-cell interaction. If cells had direct and competitive interactions, they would be much more difficult to regulate for the benefit of the organism, and each cell would need more energy all the time without doing anything useful in return, making it less valuable to the organism. So cells mostly ignore each other, because it's more efficient for the organism that they do so.

An organsim already has specialized cells to deal with this sort of thing, which make up the immune system. But killing a cancer cell here and there isn't really enough, because the underlying genome of all cells degrades over time. Even if the immune system could kill 100% of cancerous cells, the body would only produce more of them over time. And because cancer tends to set in after a long stretch of reproductive potential for the organism, it's not terribly efficient that the immune system be any good at rooting out cancer cells anyhow, from an evolutionary perspective. But if you want to clamp down on "bad" cells, like cancer cells, then it's the immune system that would be doing it, rather than other cells that just happen to live nearby.

Cancer cells return no value to the organism, and demand a lot of energy, but are not capable of persisting without the organism. They cannot be successful without the organism, and they can't spread to a new host. They aren't dominant in a significant sense, and they certainly aren't healthy. They are dead ends.

Apart from sharing the same DNA as our other cells, how is the cell:human::terrestrial species:earth so wrong?

If we over compete for resources on earth we could very easily end up making the earth a dead planet and end up killing ourselves.

IWAMG (I was a molecular geneticist)

Most mutations damage the host organism (see: cancer). It's MUCH more probable that any error will be damaging rather than harmful -> it's easy to break a protein with a few point mutations, it's very hard to change one in a beneficial direction.

Therefore you would hypothesize that It is to the benefit of the individual to do everything in it's power for DNA not to change. In practice this is actually what we find: There are whole hosts of proteins whose job it is to scan through the DNA looking for copy errors and fixing them. In fact, the malfunction of some of these proteins is thought be a significant causal factor in many forms of cancer. Proteins break down -> mutations happen -> cells no longer die off when they malfunction -> you get unregulated cell growth -> this is cancer.

So, no. To the best of our current knowledge, organisms do not have anything that would encourage mutation. In fact the opposite is true: organisms have lots of proteins that attempt to fix point mutations.

You do have systems like cross-over that happen during meiosis which vary the gene set that your offspring will get. But that operates at the level of whole genes, it does not encourage mutation within individual genes. A lot of the benefit of this goes to the immune system since it allows you to basically combine your parent's immunities and give them to your child instead of just giving them one set or the other.

-me

Apart from sharing the same DNA as our other cells, how is the cell:human::terrestrial species:earth so wrong?

If we over compete for resources on earth we could very easily end up making the earth a dead planet and end up killing ourselves.

I assume you're responding to my post responding to mikeman. My point in that post was that cancer is not a problem of non-cancerous cells in the vicinity of cancerous ones being not competetive enough, as increased competition from other cells would be worse than cancer, not better, because once cells fight amongst each other for resources the destruction of the host organism is guaranteed.

The sharing DNA part is a pretty big consideration to consider things "apart" from. But here's my reasoning:

1. Resources don't have anything to do with the reproductive advantage of a cancerous cell, nor do they compete any better for the resources that are there. You can make the argument (as you are) that the abundance of resources in a human body coupled with the lack of interest of the top-down control structure in managing cancerous cells creates a very special niche which any cell can exploit by reproducing a ton, but...

2. Unlike organisms in a given environment, cells have very specific functions.

2a. All functions of all cells are expressly for the continuation of the overall organism, with the payoff for the cells being the continued introduction of resources. As soon as cancer develops, it guarantees that this process will end. A cell line could continue forever if the organism continued to thrive, and even though cancer isn't the only possible end to thriving, the organism doesn't move past it. It's only in the last few decades that many people have lived long enough to die of cancer, but if you live long enough you will develop it, and if nothing else kills you, cancer will.

3. Genetic traits are not limited to a single organism. If you look at the lineage of cells through generations of organisms, non-cancerous cells are vastly more numerous than cancerous ones. Genetic similarity of parent to child declines by half with each generation, but one genetic difference that is never passed from one generation to the next is an inferior copy of (or lack of) the p53 and RAS oncogenes. Cancerous cells are not more successful at persisting through time and through successive generations than non-cancerous ones.

If you want to look at a single organism at a time, you can look at cancerous cells as superior in the sense that they reproduce faster. But they are not different from other cells in any other "competitive" capacity. And the strategy that they follow is not possible in any environment other than the one that they inhabit, which is almost entirely absent of selection pressures. So any analogy that you make to other environments isn't going to go very far, because no other environment is like a multicellular organism.

ITT: a bunch of people fail at understanding biology, genetics and evolution.

ITT: a bunch of people fail at understanding biology, genetics and evolution.

What do you mean "a bunch"? I'm the only one!

It would help a bit if you helped me with those failings though, I never claim to understand much about those things, just asked some questions on a lounge thread. Anyway...

There are plenty of feedback loops within organisms evolution, ie copy proteins evolve or more precisely mutate and this in turns cascades to more mutations which under some conditions might be favorable.. ie the case where the DNA repair mechanisms makes duplicates, this creates redundant copies of functional DNA which then can start to evolve independent of the main gene without the detrimental effects of losing the original gene .. Some biologist theorize this is how the multi-segmented nature of arthropods evolved and specialized.. etc..

Evolution isn't directional its equalvalient to a breadth first search in gene space, and it can get stuck and there are a few "tricks" which have evolved to get organisms out of these local maxima (ie lossy copying of DNA during replication, crossover, gene exchange with foreign species, etc..).. The feedback loops extended far beyond the organism to the network of organism and ultimately to the entire planet.. Ie photo-synthetic plants produce oxygen, causes oxidation of rocks and minerals, creates a ozone layer which allows terrestrial life to take hold, colonizing the land leading to massive influx of solar radiation being captured, changing the world wide weather patterns and increasing temperatures, etc.. all because a few plankton evolved the ability to break down CO2 using sunlight..

So ur ideas are sound, yes evolution occurs are multiple levels within an organism from the genetic, bio-chemical all the way up to the social and they feedback in ways we can't even comprehend.. Who knew a variation in skin melotonain would result in the social strife in human society which would lead to generations of conflict for humans..

-ddn

If cell DNA "evolves" with a random change and your organism has trillions of cells each with a small chance of evolving, it's only a matter of time until one of those cells accidentally creates an infinite loop. Then you've got a cancerous cell! Considering that's how it actually happens, I'm amazed that the cancer rates are so low when you think that you've got all these harmful chemicals and radiation sources everywhere.

I assume you're responding to my post responding to mikeman. My point in that post was that cancer is not a problem of non-cancerous cells in the vicinity of cancerous ones being not competetive enough, as increased competition from other cells would be worse than cancer, not better, because once cells fight amongst each other for resources the destruction of the host organism is guaranteed.

The sharing DNA part is a pretty big consideration to consider things "apart" from. But here's my reasoning:

1. Resources don't have anything to do with the reproductive advantage of a cancerous cell, nor do they compete any better for the resources that are there. You can make the argument (as you are) that the abundance of resources in a human body coupled with the lack of interest of the top-down control structure in managing cancerous cells creates a very special niche which any cell can exploit by reproducing a ton, but.

2. Unlike organisms in a given environment, cells have very specific functions.

2a. All functions of all cells are expressly for the continuation of the overall organism, with the payoff for the cells being the continued introduction of resources. As soon as cancer develops, it guarantees that this process will end. A cell line could continue forever if the organism continued to thrive, and even though cancer isn't the only possible end to thriving, the organism doesn't move past it. It's only in the last few decades that many people have lived long enough to die of cancer, but if you live long enough you will develop it, and if nothing else kills you, cancer will.

3. Genetic traits are not limited to a single organism. If you look at the lineage of cells through generations of organisms, non-cancerous cells are vastly more numerous than cancerous ones. Genetic similarity of parent to child declines by half with each generation, but one genetic difference that is never passed from one generation to the next is an inferior copy of (or lack of) the p53 and RAS oncogenes. Cancerous cells are not more successful at persisting through time and through successive generations than non-cancerous ones.

1. Yes they do.
2. So do organisms in an environment.
2.a. No they are not. A liver cell does not think, "Oh damn this dude is drinking a lot so I better work extra hard so he can feel good and every cell in the body can live longer," it just does it's job. For all it knows it could be outside the body as long as it's still getting everything it needs to survive. It just so happens that what it does is beneficial to the whole system and the whole organism can live longer.
3. They do in the sense of a body being the environment. If we over-reproduced and killed our planet by using up or blowing up all the resources we would all die just like cancer cells die when the body dies.

You are still looking at cells as cells. To understand the analogy look at a cell as an organism and the body as the environment.

If you want to look at a single organism at a time, you can look at cancerous cells as superior in the sense that they reproduce faster. But they are not different from other cells in any other "competitive" capacity. And the strategy that they follow is not possible in any environment other than the one that they inhabit, which is almost entirely absent of selection pressures. So any analogy that you make to other environments isn't going to go very far, because no other environment is like a multicellular organism.
[/quote]

Faster reproduction is a HUGE competitive advantage. It's absolutely astronomical in how big a competitive advantage it is.

and I'm not so sure you have argued quite well enough to nullify the Terrestrial organisms:Earth::Cells:People analogy. Every organism serves it's purpose in the environment of the earth.