For instance http://www.nature.com/nature/journal/v441/n7092/full/nature0... has an example of RNA-based inheritance that is not in the genome. Also http://en.wikipedia.org/wiki/Genomic_imprinting shows that what genes you have and what genes you express are two different stories entirely.
That said, the effort of transcribing the 50 MB of genomic information into the final program is simply not a problem. And if we wanted to transcribe a much larger genome, the additional effort for that is again bounded.
This is all, of course, ignoring the excellent point that one would never want to actually do this given how slow this emulator would have to be. If we create AI in the next few decades, I can guarantee that it won't be a physics emulation of a human brain.
When you argue that a simple (just a few rules of physics) emulator could, in principle, do the job -- quite right. Unfortunately for your point, Kurzweil is making a much, much stronger claim. For, surely, you agree that that physics emulation isn't going to result in a practical program in 20 years, yes?
The way you are using "upper bound of the problem in terms of complexity" there... I could use your same logic to argue that the design of a brain can be encoded in exactly 1 bit.
The design of a brain, by your logic, contains 1 bit of information. (In particular, that 50 MB of compressed genome data? I'll give you a better compression algorithm for this purpose and it will, indeed, compress a particular human genome down to 1 bit.)
Since all Turing complete machines are functionally equivalent I don't think it is quite that irrelevant.
if the brain can be simulated by any Turing machine at all it figures that a 2-d tape Turing machine can do the same thing.
The question then becomes how big is the total information content of both Turing machine + tape.
The rules of physics are Turing complete, we use them to build computers with and nature uses them to build the physical universe, including computers and brains.
Kurzweil is not making such a strong claim at all I think, he merely argues that there must be some upper boundary to the starting configuration from which you should be able to arrive at a working brain.
And much as I would like to I can't find fault with that other than that the embryotic development is chaotic in nature and that a very small change in input conditions can easily produce nothing of interest on the output side.
The conclusion that we can draw from that is that the brain (and in fact probably every cell in our bodies) must contain a great deal of machinery to make sure that the process stays on track and does not veer off in to chaos and unpredictable outcomes. For the most part, it works, most of the fetuses carried to term are able to think.
> For, surely, you agree that that physics emulation isn't going to result in a practical program in 20 years, yes?
Some people claim even shorter times than that (which I think is highly irresponsible):
http://www.dailymail.co.uk/health/article-1201724/Artificial...
Personally I would put the time required for such a project in the multiple decades, probably 50 years at a minimum, maybe much more assuming that it can be done and that there is no quantum component (as proposed by Penrose, rather weakly) to intelligence.
As for your 1 bit description, you are not taking in to account the information content of the guts of the compression algorithm, and you'd find that algo+compressed data would work out to a nearly constant amount of information.
That 50MB has been created in a way that the size of the algorithm required to compress it and decompress it is relatively small compared to the size of the data.
As soon as you start embedding codebooks inside your algorithm the size of the data will go down but the size of the algorithm goes up correspondingly. Also the algorithm loses its universal character, it's ability to encode multiple data sets with roughly equal characteristics in terms of information content in to roughly equally sized output.
The complexity of a Turing machine is a function of the number of states that it can encode, in programming languages we call that 'expressiveness'. You can write a smaller program in a language that is more expressive. A Turing machine that allows more states is going to require a shorter tape (fewer cells) to do its work but will be more complex.
The argument I think that Kurzweil makes with his 50 MB figure is that once you take out all the redundancy you've taken out the expressiveness factor. Whatever emulator you use to interpret that 50 MB you'll end up with some 3D structure (if you simulate the embryology properly) that will resemble a brain.
The part where the analogy goes wrong according to me is by postulating a machine that this stuff should run on. The 'emulator' is nothing but the endless repetition of ribosomes threading RNA in order to produce more polypeptide chains which then fold up in order to become proteins.
Your 'emulator' in this case is a physics program, and not even a very complicated one, albeit with an absolutely astronomical data set for any size organism.
In order to avoid having to deal with that data set we try to achieve a higher level model of what the brain does, instead of trying to model what it is.
But that does not change the fact that the principle of the emulator (a 'mere' matter of programming) and the code that governs the construction are what gives rise to the brain and through there to intelligence.
So the upper bound of the problem in terms of complexity is the 50 M + whatever you need in terms of physics to (theoretically) run the simulation of the single fertilized ovum from start to finish, or as much as you need to verify that you have indeed succeeded in your simulation goal.
It can't get more complex than that, even if the generated structure is orders of magnitude more complex at first glance than the input data + the program. Think of it as 'output'. Thought is not the output of that program. Thought is the state changes within the produced (or simulated) brain.
The organic soup and all the proteins arising from it are the nuts and bolts the machinery is made of. That doesn't mean that we can't make similar machinery without those particular nuts and bolts.
I hope that all makes sense.