If you look at fingerprints or the spongy interior of bones, clearly there's a lot of detail there. But the position of every skin whorl or bone void is not specified directly by a gene. Identical twins don't have identical fingerprints. This doesn't matter for finger or bone functionality, as long as the material works on a statistical, higher level. If you think of it as a blueprint for a bone, like for a building, the specification just says "x percentage of void with average cell size y and variance z", just like a building specification doesn't specify the location of every grain of sand.
And of course then it also grows in response to how it's stressed. Anyway, this is because it wouldn't make sense to store all the exact information, you just store some metadata and generate the actual stuff when building. Also you do testing and build more after that.
With the brain, it's the same, the amount of neurons and synapses is large compared to the amount of genes or "blueprints". But in a brain, as opposed to a bone or a finger, because the whole thing is designed to amplify weak signals, detail differences can have more effect on the function of the whole. There is this whole internal testing pattern going on while the brain is being built, but it seems it's not so perfect that clear differences creep in easily.
Yes, I was surprised that the article didn't mention neurogenesis. It's worth pointing out a result from game theory: Given related individuals (using the example of two shepard brothers who may signal each other for help) there are many signaling equilibria. The particular path is sensitive to random initial conditions. Interestingly, even for a simple game where a non-signaling altruistic solution dominates, a signaling solution reliably emerges and converges.
Game Theory Evolving, Herbert Gintis, 2000 (first edition), pp 321-323.
If you look at fingerprints or the spongy interior of bones, clearly there's a lot of detail there. But the position of every skin whorl or bone void is not specified directly by a gene. Identical twins don't have identical fingerprints. This doesn't matter for finger or bone functionality, as long as the material works on a statistical, higher level. If you think of it as a blueprint for a bone, like for a building, the specification just says "x percentage of void with average cell size y and variance z", just like a building specification doesn't specify the location of every grain of sand.
And of course then it also grows in response to how it's stressed. Anyway, this is because it wouldn't make sense to store all the exact information, you just store some metadata and generate the actual stuff when building. Also you do testing and build more after that.
With the brain, it's the same, the amount of neurons and synapses is large compared to the amount of genes or "blueprints". But in a brain, as opposed to a bone or a finger, because the whole thing is designed to amplify weak signals, detail differences can have more effect on the function of the whole. There is this whole internal testing pattern going on while the brain is being built, but it seems it's not so perfect that clear differences creep in easily.