Some great replies!
Something about the structure of the brain must be genetic, since it develops in the womb in the first place. The brain isn't made out of one homogenous type of material either, and it is genetics that create these different areas of the brain and map for the proteins and hormones that send messages and allow our body to 'know' how to grow. Most of our thinking doesn't come from learning input, either - neurons are firing that allow us to breathe, and our organs to function. This doesn't all come from learning or the development of a completely blank slate brain. So if all that can organize itself from genetics - I imagine a whole lot else can too.
I'm not convinced. By "input" I don't necessarily mean human consciousness level input. Input might be something as simple as chemical processes resulting in lower oxygen in one part of the brain if something does or doesn't occur. What I mean to focus on is the neurons themselves: what creates the distribution and associations?
Certainly some of this is genetic, but where is that line? In an indirect sense, it is perhaps all genetic. Then another way of looking at it is this: is the human brain special in its organization or just its parts?
But this is all from a product of long slow evolution. I agree that 'universal grammar' is unlikely to have evolved or even be selected for - but I don't know if the immense amount of neurons supports this.
Agreed. Humans are certainly genetically capable of language, but to hint that there's some linguistic structure encoded in the DNA is, I think, an extreme position. Moreover, what I find really hard to understand is how it would be implemented neurologically if neurons are not distributed and attached based on DNA.
As I understand Chomsky's argument (or perhaps more from the Biolinguists who closely associate with his most recent ideas), the idea is that human language evolved about 100,000 years ago suddenly with one simple change-- therefore, Minimalism is the project trying to find that simple change. It was described to be as "a specific neural circuit" [that is unique to language and the biological encoding of
Merge].
Among many objections I have.... how could such a circuit be implemented in the DNA?
Or do those bioliguists just have no idea what they're talking about in terms of brain circuitry, using awkward, inaccurate metaphors about "circuits" then they really mean algorithm?
Well, there must be some design to the whole system, right?
Why. I don't take that as a given. It's an expected first assumption, and it may also be correct. But let's not start by assuming it is axiomatically true.
I mean we all have specific regions that host different clusters of cells in the brain that display similar functions across the species. The Brodmann Classification System would just make no sense if there wasn't an underlying structure that tied clusters of neurons that carry out a specific function to a specific area. Having said that, we all know that this isn't fixed and damage to one locus of the brain can result in even the other hemisphere taking on the load and rewiring of those specific functions, all demonstrations of Hebbian theory ("Neurons that fire together, wire together.")
Locations in the brain are notoriously difficult to find (eg, the whole "modularity of language" thing, or even just finding out where language neurons are beyond some of the basics). And they can change.
I would certainly agree with you: the general layout of the brain is definitely genetic, just as much as having feet and no tail is. But that's roughly a mold then. Within that mold, are the neurons themselves structured genetically? Or are they more like some kind of concrete, poured into a mold and left to fill and solidify in naturally?
For example, I can imagine a specific gene that determines the size of some specific region in the brain and something about the kinds of cells that go in it. But that is still remarkably little! Or is the actual location somehow relevant to why humans are so good at thinking? What if the brain were somehow inverted in a crazy way? Would that not work? Is there anything unique and important about the human brain, or is it just that roughly anything along those lines would work out for us?
More importantly, there is another explanation for localization: input. The brain operates in layers and the outermost neurons are, of course, in contact with various kinds of input, such as in the ears. It would be very odd if some ear-related part of the brain was located near the spinal chord; we expect it to be near the ears. And so it might just be a usage/input effect where whatever layers happen to connect eventually reach the right configuration.
There would have to be a basis, but on top of that basis, a loose system of inter-connectivity that had the freedom to join and be moulded based on specific electrical input. The architecture must be there and if your question is about what happens after that architecture is in place, then I understand your question a bit more.
Agreed, and yes.
To abstract away a bit more (and perhaps clarify what I'm thinking about), imagine trying to build a mind on a computer-- would it require a specific kind of neural network with exactly a certain configuration? Or could it approximate the distribution, properties and density of neurons in the brain and just randomly cycle until it worked?
When you look at genetic motor disorders, there is a lot of convincing evidence that this caused by the distribution of neurons in an atypical fashion (genetically inherited) which is likely to have been inherited in the genetic code and therefore mapped via some building block (plan) that would imply a pretty specific plan of neuronal distributions.
This is very relevant. But is it certain that the genetic inheritance is not in the form of broken neuron instructions? That is, the actual structure of the brain is not genetic, but there is some genetic mutation that causes a specific type of neuron (perhaps in combination with some other factor) to not generate a normal brain?
Having said that, there is clearly some crazy acrobatic qualities to the system and the interplay of those systems is not something I believe is well understood in neuroscience in general.
Quite literally, individual neurons appear to respond to specific stimuli, such as a certain color of light at a particular angle in a particular corner of the eye. There's a neuron for that. But obviously if that particular neuron dies, along will fill in, etc. (Probably with some redundancy too.)
That's a very powerful ability and completely structurally based. But with the flexibility, it looks less and less like any particular neuron (and therefore any group of neurons) has any predetermined properties, except roughly where they end up in the body. With 86 billion neurons, let's even say there are 86 specific subareas with unique dimensions. That's fine. But there are still one billion neurons in each area not distributed or connected by specific instructions in the DNA!
Freknu, neuroplasticity is used quite a bit (I've come across it especially for discussions of language acquisition, but that's a tangent).
Both physically and mentally our minds are quite "plastic", or mouldable, responding to both internal and external "stimuli" of various kinds. So although we most certainly do have some kind of inherent "design" to our brains, like any other part of our body, it wouldn't surprise me if the brain was able to "reshape" itself to environmental pressure.
If reshape, then why not shape as well?
Or at least when it comes to the neocortex? The deeper you go into the brain, the closer to autonomous functions, this probably doesn't hold anymore. This might even be the evolutionary advantage of our large neocortex.
This is, I think, a crucial point. Let's phrase it as a question: does the distribution (and/or attachment) of neurons correlate more closely with genetics for the more core functions? Are the neurons that control the heart and lungs any more/less plastic or randomly distributed than those for language or those for creating art?
You may very well be right, but if so, why?
Or? Neurology isn't exactly my specialty, lol
Me neither. I'm coming from Linguistics > Psychology > Neuroscientist (plus maybe a stop by computational theory on the way). I wouldn't even consider myself a psychologist, must less neuroscientist. But it is interesting!
I understand that recently neuroscientists have found that neurons tend to be organized in "motifs" (AKA "neural legos"), which are small groups of neurons (10 or fewer neurons) with the same patterns of connections between them.
This is what I'm talking about. Looks like it's cutting edge research, so maybe this is a good question for the moment after all

See my note about Chomsky, Minimalism and Merge above: I imagine they'd want the "Merge/language circuit" to be a type of motif!
Now I have a few things to read. Thanks for the links.
I agree that it is unlikely for individual connections to be genetically coded. However, I think it is possible for the relative prevalence of various motifs in different regions to be genetically coded; some regulation sequence makes a particular motif (= deterministic transformation of inputs) more or less likely at some point in development.
What you're describing seems more like an unstructured version: neurons are predetermined to do certain things but they get distributed randomly. And in some cases (perhaps even most/all) the neurons may be set up / released in prefabricated configurations, but then still sent out randomly. In other words, for a computer program modeling this you'd just need an example of that "motif" and
then at that point just send a bunch of those out into that region of the brain and work from there.
I'm not sure how this would fit with the particular view of UG that has been developed in the Generativist literature. However, if we are willing to consider a broader view of UG, then UG may just be a particular probability distribution over these motifs, or over structures of these motifs.
Yes, much more reasonable. Still far from proof that "UG" is anything special, though. (It might just be more of the same, from elsewhere.)
All of this is highly speculative, of course. As far as I know, these motifs have not been directly implicated in language behavior, and may be too low-level to have any discernible reflex in language.
I wonder if the biolinguists would attach themselves to such a claim. I wouldn't be surprised. I don't really know though.