3 ms·

Agreed. That's like orders of magnitude orders of magnitude. Definitely surprising, although in one of those hindsight realizations -- c.elegans has a specific

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?

lend000 9y ago
> 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.
devrandomguy 9y ago
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 https://en.wikipedia.org/wiki/Hemispherectomy
kleer001 9y ago
> 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
mirimir 9y ago
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/ https://www.ncbi.nlm.nih.gov/books/NBK27140/ 1) https://www.ncbi.nlm.nih.gov/pubmed/12558794 https://www.ncbi.nlm.nih.gov/pubmed/12558794

lend000 9y ago

> 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.

devrandomguy 9y ago

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 https://en.wikipedia.org/wiki/Hemispherectomy

kleer001 9y ago

> 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

mirimir 9y ago

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/ https://www.ncbi.nlm.nih.gov/books/NBK27140/ 1) https://www.ncbi.nlm.nih.gov/pubmed/12558794 https://www.ncbi.nlm.nih.gov/pubmed/12558794