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Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

biology.stackexchange.com

141–150 of 204 posts

Re: Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

#142

Something to be aware of as a computer person coming into biology: Biology only _looks_ like it has logical constructs, abstraction layers, and general computational frameworks. When you start working with it, you'll find everything is messier than you expected and everything interacts with everything at every level. There are no abstractions, there are no actual boundaries, and your outputs are subject to evolutiona…

Computers only look like they have windows, digital signals and logic gates. It's all just pixels, noisy voltages and imperfect silicon.

Sure, but because of the transistor’s nonlinearity (cutoff and saturation regions, for mosfet at least), we get digital logic. Digital logic means that errors don’t accumulate, and that prevents complexity from infecting everything in the computer. We can put neat little abstraction boxes around parts of the SoC, and then do the same with our software.

Digital computers are only noisy compared to the simplest processes, like a low rate transmission line. Compared to biological or chemical processes, a digital computer is just ludicrously low-noise, because noise doesn’t propagate unless there is a major fault.

Re: Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

#143

Something to be aware of as a computer person coming into biology: Biology only _looks_ like it has logical constructs, abstraction layers, and general computational frameworks. When you start working with it, you'll find everything is messier than you expected and everything interacts with everything at every level. There are no abstractions, there are no actual boundaries, and your outputs are subject to evolutiona…

I would argue that it is only messy because we are looking at the wrong level of abstraction with an incorrect computational model. At the end of the day, if it has inputs and produces outputs, it is a computing device (i.e. a computer).

Seems like an overly broad definition. A pizza oven has inputs and outputs but you would probably struggle to find someone willing to call it a computer.

Re: Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

#144
post #76

Earlier quoted context omitted.

Yeah I think there's a paper about how brains most likely represent some things with quantum states which may explain why we don't understand them yet.

There are many such papers. However they need to be understood as extremely speculative, if not outright woo-woo, as there is currently no reason to believe that the brain is capable of maintaining any sort of even modestly-large-scale entanglement properties. These papers, and people commenting on them, also often appear to believe that just finding that entanglement is happening would itself mean something; it's no…

People are desperate for "quantum" to be involved in the brain because it's the only possible way to resolve "Physical processes are mostly deterministic" -> "The brain is a physical process" -> "A deterministic brain means truly no free will, which has serious philosophical and ethical implications".

Re: Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

#145
post #60

Earlier quoted context omitted.

Yeah, except you can only change one line at a time and you lose all of your changes if it doesn't compile at any point.

Sex changes many lines at a time. But you do die if it doesn’t compile.

My friend who has a defective genome including a specific enzyme that doesn't "compile" and he is plenty alive

Re: Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

#146

Something to be aware of as a computer person coming into biology: Biology only _looks_ like it has logical constructs, abstraction layers, and general computational frameworks. When you start working with it, you'll find everything is messier than you expected and everything interacts with everything at every level. There are no abstractions, there are no actual boundaries, and your outputs are subject to evolutiona…

The I think about it is like this: Code is read and maintained by humans, so it is under selection pressure to be comprehensible by human minds. Reality has no such constraint. If the biological processes of some animal lead to inscrutable irreducibly complex "spaghetti code" but the animal is slightly more likely to produce offspring... the complexity wins. The natural world doesn't care whether or not we can unders…

> The natural world doesn't care

I always find this kind of phrasing problematic due to its implicit anthrophomorphic metaphors.

Whether spaguetti code or not, I think that people often just assume that we have the capacity to understand it give the period of time between now and when humans disappear (because of evolution, a meteorite, climate change or human intervention). I am highly skeptical. Maybe, whatever species emerges after us, might have a better chance but to them we might be no different than a homo erectus is to us homo sapients.

Re: Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

#147

Something to be aware of as a computer person coming into biology: Biology only _looks_ like it has logical constructs, abstraction layers, and general computational frameworks. When you start working with it, you'll find everything is messier than you expected and everything interacts with everything at every level. There are no abstractions, there are no actual boundaries, and your outputs are subject to evolutiona…

Yep -- there was a thread a while about whether a biologist could reverse-engineer a radio, and I made the comment that electronics are designed to keep the various functions nicely decoupled, while biological systems aren't/don't, because they optimize for something else, leading them to bleed state across the entire system:

https://news.ycombinator.com/item?id=32048972

(Also links to previous discussions on this theme.)

Re: Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

#148

My favorite thing about mtDNA is that two separate genes overlap using separate reading frames. The end of one gene is the same as the start of another, and they are laid out in the circular mitochondrial genome to take advantage of this fact. I've also read that DNA chromosomes can under go conformal changes in response to the environment it's in, making certain reading frames more or less likely to be transcribed,…

I think you'll find some of the tricks that (mostly) viruses use to be interesting. Take a look at ribosomal frameshifting [1], where the viral RNA has a special structure such that at a certain point during translation in the ribosome it will skip back 1 nucleotide (a -1 frameshift; -2 and +1 frameshifts have been observed as well, more rarely), thus changing the whole reading frame. Viruses use this to encode multi…

Fuck that’s crazy.

For the CS people who don’t understand what this means, a rough analogy is that HIV does something like steganography to encode two proteins in one gene.

Re: Does DNA have the equivalent of IF-statements, WHILE loops, or function calls?

#150

Earlier quoted context omitted.

The I think about it is like this: Code is read and maintained by humans, so it is under selection pressure to be comprehensible by human minds. Reality has no such constraint. If the biological processes of some animal lead to inscrutable irreducibly complex "spaghetti code" but the animal is slightly more likely to produce offspring... the complexity wins. The natural world doesn't care whether or not we can unders…

> Brains that understand the natural world do seem to often be generally more likely to produce offspring I would argue that the evolutionary pressure only applies to a limited level of understanding of the physical world. Think how many kids people like Stephen Hawkings have and how many poorly educated people have.

On the other hand I would argue that evolutionary pressure works differently for modern humans in the 20th century and beyond than it did for the majority of human evolution.

Sure uneducated people now often have more kids due to less contraception options/knowledge and as old age insurance. But then again rich people have more kids than middle class because of well more money and everything that comes with it.

In any case all of this is anecdotal and emotion based because there is not much good data on this. Or maybe there is?

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