> There are no laws of nature that prohibit redundant replication of data
There most certainly are, at the information density of DNA. DNA is about a thousand times more information dense than our best hard drives. At that level, a passing photon can change or break enough chemical bonds to alter the bits. A nearby high-energy molecule can do the same. This actually happens gazillions of times per day in our body and we have a few hundred enzymes to automatically correct errors and a few hundred more to detect when those can't fix the problem and shut down the cell. The fact that it works at all is jaw-droppingly amazing. We take copying bits on and off hard drives for granted, and they only work for a few years max--cells operate on an entirely different scale of information transfer and yet some multicellular organisms live for centuries.
Unfortunately, I don't think you could improve the error checking mechanisms in our cells without fundamentally redesigning a lot of how we work. It would be interesting to try to add more "parity" mechanisms besides the complementary base pairing, which is used by most of the repair enzymes. From an evolutionary standpoint, no species would ever naturally develop perfect DNA replication because it would halt diversification, which is needed to survive continually changing environmental threats.
I should also add that it's a misconception that every cell in our body has the exact same DNA. That's only a half-decent approximation. In reality, a lot of our cells accumulate trivial mutations and it's OK. Some cells even rely on editing their own DNA to perform their primary function: that includes the B and T cells [1] which the cancer in the OP arise from.
Your points on how curing cancer basically cures aging and the fact that we can't prevent copying errors are spot on. That's why I've often thought that the recommendations people make for preventing cancer (taking antioxidants, avoiding certain foods/chemicals) probably have little or no impact on the odds of getting cancer, or are even counterproductive because they prevent apoptosis. What seems to generally work better is simply eating a variety and exercising, and assuming that the body is being bombarded by mutagenic toxins/radiation constantly and trying to stay strong in the face of them so that if (when) the time comes to undergo treatment, the body has enough reserves to survive it.
My gut feeling is that the final cure for cancer (and by extension aging and other diseases) will come about through a much simpler mechanism (more basic I mean, not easier), more in line with engineering than medicine. They’ll need to be able to systematically map any type of cell in the body and trigger its death, then insert a replacement cell at that site or coerce the body into doing it. It may not be possible with just our immune systems because it’s an area that evolution overlooked and we just don’t have the genes and cellular machinery for it.
I’m really skeptical that we’ll have nanobots to do that anytime in the foreseeable future, but, there are tons of other options like engineered viruses or chromosomes that don’t seem nearly as far-fetched. If we forget about medicine for a moment and just think about the fact that the compressed human genome fits on a CD, then the mutations in a cancer cell are going to be much smaller than that, potentially small enough that they can be encoded as something akin to lisp programs. They could find markers from a cancer cell in the lab, and then evolve genes to recognize them and tag or kill the cells with genetic algorithms in a computer. When we hear about engineered viruses killing the people they were meant to treat, I think that happens because humans just can’t program something like that manually. It has to be evolved over generations to take into account countless factors that might not occur to us.
To me, that kind of simulation is straightforward. It’s just another big data problem, and we need better sequencing so that patients can get loaded into a computer cheaply. Once a solution has been evolved with a high degree of certainty (like thousands of times the confidence level of anything today), and has a reliable cutoff switch, then synthesizing that becomes “just an engineering problem”.
TL;DR: We need github for medicine so that all of the tools in the arsenal can be recruited as external libraries and simulations can be run in a distributed fashion by hackers who handily find solutions to any problem that’s thrown at them but can’t be bothered to obtain medical degrees.
There most certainly are, at the information density of DNA. DNA is about a thousand times more information dense than our best hard drives. At that level, a passing photon can change or break enough chemical bonds to alter the bits. A nearby high-energy molecule can do the same. This actually happens gazillions of times per day in our body and we have a few hundred enzymes to automatically correct errors and a few hundred more to detect when those can't fix the problem and shut down the cell. The fact that it works at all is jaw-droppingly amazing. We take copying bits on and off hard drives for granted, and they only work for a few years max--cells operate on an entirely different scale of information transfer and yet some multicellular organisms live for centuries.
Unfortunately, I don't think you could improve the error checking mechanisms in our cells without fundamentally redesigning a lot of how we work. It would be interesting to try to add more "parity" mechanisms besides the complementary base pairing, which is used by most of the repair enzymes. From an evolutionary standpoint, no species would ever naturally develop perfect DNA replication because it would halt diversification, which is needed to survive continually changing environmental threats.
I should also add that it's a misconception that every cell in our body has the exact same DNA. That's only a half-decent approximation. In reality, a lot of our cells accumulate trivial mutations and it's OK. Some cells even rely on editing their own DNA to perform their primary function: that includes the B and T cells [1] which the cancer in the OP arise from.
[1]: http://en.wikipedia.org/wiki/VDJ_recombination