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Comment by daveguy | Hacker News Reader

Agreed. That's like orders of magnitude orders of magnitude.

Definitely surprising, although in one of those hindsight realizations -- c.elegans has a specific consistent function for each cell and each cell under normal development.

If 300+ cells of a worm can be that well orchestrated, of course slightly more complex creatures could. Evolution is a series of slight successes.

What if the cells of the brain have their own genome because each one of the billions of cells has a near specific specialized function.

Could cellular function be that precise? Each micron of tissue the result of specific evolutionary pressures?

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I suspect that it's much like the immune system. For example, antibody diversity is "generated by DNA rearrangements during B-cell development".[0] And:[1]

> In another parallel with the immune system, cadherin-related neuronal receptors (CNRs) are diversified synaptic proteins. The CNR genes belong to protocadherin (Pcdh) gene clusters. Genomic organizations of CNR/Pcdh genes are similar to that of the Ig and TCR genes. Somatic mutations in and combinatorial gene regulation of CNR/Pcdh transcripts during neurogenesis have been reported.

So as with evolution, more-or-less random variation generates diversity in the developing nervous system. And then there's selection.

0) https://www.ncbi.nlm.nih.gov/books/NBK27140/

1) https://www.ncbi.nlm.nih.gov/pubmed/12558794

> What if the cells of the brain have their own genome because each one of the billions of cells has a near specific specialized function.

That's the opposite of my interpretation -- it goes to show that even in the face of inevitable statistical noise, biological systems are incredibly fault-tolerant and durable. And furthermore, a neuron is just a neuron. It's unlikely that the genomic differences in a genius's neurons are significant compared to the overall genetic average which gave rise to a certain structure, certain proteins being more common, etc.

An interesting hypothesis, but difficult to reconcile with the surprisingly successful history of hemispherectomy [1]. Unless, perhaps, many unique neurons still serve nearly identical functions, despite their differences? Perhaps their uniqueness is a defense against disease, rather than functional specialization?

I don't mean "functions" in the sense of classic neuroscience, like specialized regions of the brain; I am using it as a very generic term, for lack of a better one.

[1] https://en.wikipedia.org/wiki/Hemispherectomy

> Could cellular function be that precise? Each micron of tissue the result of specific evolutionary pressures?

If that's what the data says.

It's probably an emergent quality from a set of simple rules being iterated. You can do a lot with a very very little if you're procedural about it.

z_(n+1)=z_n^2+C

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