Questions about the human body

[Ogre]

Progress in cellular differentiation is controlled by feedback mechanisms.
Cells produce A which initiates the production of B and turns off the synthesis of itself. B produces C and turns it own and A's production off. C, in the presence of A, modifies the DNA chemically to exclusively produce either D or E depending whether or not it receives F from a neighbouring cell. Such interplay quickly becomes complex, but allows many opportunities. Why does the first cell not produce F you could ask. Because one cell was first to produce A and thus B and C - and B goes to the second cell and turns it production of A and B off. Therefore C never appears in the second cell, which then produces F instead. Now you have precursor states for different tissues.
With feedback self-regulation the opportunities are endless.

This is a bit off topic but:
I was wondering if computer electronics could be modelled in this way? (if they aren't already). I don't know enough about computer engineering, so I am not sure if it is possible.

[mistergreen77]

It is a bit off topic - electronic circuits are based on boolean logic schemes. Everything is true/false but with this primary assumption computers are able to model many complex real processes. Feedback loops are of primary importance to artificial intelligence systems. I think the study of self-regulating systems is called cybernetics. Electronics of course cannot grow and replicate the way DNA does so don't be thinking of pregnant robots anytime soon.

Perhaps I am showing my ignorance, I get the bit about the potential for distinct tissues developing as part of the self-regulating feedback loop etc. But I was under the impression our DNA does not differ that much from any other DNA. So what puzzles me is if our dna is so similar why do animals all look so different?

[Zandrav Ibistenn]

I was under the impression our DNA does not differ that much from any other DNA. So what puzzles me is if our dna is so similar why do animals all look so different?

We share with about 99% of our approximately 30.000 genes with chimpanzees. The clear differences between humans and chimpanzees result from mechanisms not dissimilar to those causing tissue differentiation. Some genes both species have are only active in one species. Besides many genes code for so-called "house keeping" proteins, which are proteins necessary for the basic metabolism of the cells. In humans 80% of the protein synthesis of cells produce such house keeping proteins, and it is reasonable to assume that chimpanzees share many of the necessary genes with us - a good example of how we can share many genes without it having visible effects.

Also, even a single gene can have a huge effect. Genetic diseases where the ability to synthesize just one enzyme (or produce a faulty one instead) are known for their far-reaching and deebly unpleasant consequences.

Knowing the complexity of this and other natural processes gives me a sense of wonder that is the seems to border on religious.

Indeed, the complexity of nature is quite remarkable! I was microscoping the gray matter of a cerebral cortex a few days ago and was fascinated by how finely the thousands of neurons were organized in layers with their axons lined in parallel, constituting a pathway in the central nervous system. The positioning of those neurons have been determined by the blueprint contained in the DNA within them. The workings of DNA is based on chemical interactions between its molecular constituents. And so the regression continues: The molecules are formed by atoms, which are formed by neutrons and protons - baryons (3 quark combinations) - and electrons, which are leptons. Each step adding another layer of complexity (perhaps infinitely?). In the other direction the neurons of the brain cause certain behaviors between humans, opening the possibility for cooperation, which has enabled us to build our civilization upon the autonomous work of millions of years of evolution on a small life-sustainable planet sailing the great empty void of the universe.
The organizational layers stretches from superstrings to the entire universe and the thought of our place in all that is nothing less than awe-inspiring.

But I fail to see where God comes into this... Does his influence make it any more or less fascinating? Does anything indicate his intervening hand? - No, as Laplace put it, God is a redundant hypothesis.

Pantheism, I think, is the weakest kind of faith; you have to be desperately out looking for something if you find yourself searching for it in a stone. To me, the notion that God is everywhere is equivalent to God being nowhere.

[mistergreen77]

I think I have been misunderstood. Maybe fMRI would show similarities between wonder at nature and worship of God. I am familiar with religious feelings from an earlier stage in my life and I think it feels similar. As for pantheism, I have never given it a second thought - but I think it is a step closer to the spirit of science if by pantheism they have given up belief in a spiritual world. But you are right, the concept of God does not fit within an economy of principles.

[Zandrav Ibistenn]

I didn't intend to imply anything about you, but I just felt it was an appropriate general comment, albeit misplaced here, since it obviously belongs in another thread.

Let's not stray too far from the idea of this particular thread.

Another question perhaps? Anyone? (I'll be leaving for a while after tomorrow (to serve time in hell), so it's a last call for my input).