In the last chapter of Dehaene’s Reading the Brain he speculates about one of the really big human questions: whence culture? The books big thesis, concentrating on reading and writing as vehicles for cultural transmission, is the Neuronal Recycling Thesis (NRT). The idea is simple; culture supervenes on neuronal mechanisms that arose to serve other ends. Think exaptation as applied to culture. Thus, reading and writing are underpinned by proto letters, which themselves live on ecologically natural patterns useful for object recognition. So too, the hope goes, for the rest of what we think of as culture. However, as Dehaene quickly notes, if this is the source, and “we share most, if not all of these processors [i.e. recycled structures NH] with other primates, why are we the only species to have generated immense and well-developed cultures” (loc 4999). Dehaene has little patience for those who fail to see a qualitative difference between human cultural achievements and those of our ape cousins.
…the scarcity of animal cultures and the paucity of their contents stand in sharp contrast to the immense list of cultural traditions that even the smallest human groups develop spontaneously. (loc 4999)
Dehaene specifically points to the absence of “graphic invention” in primates as “not due to any trivial visual or motor limitation” or to a lack of interest in drawing, apparently (loc 5020). He puts the problem nicely:
If cultural invention stems from the recycling of brain mechanisms that humans share with other primates, the immense discrepancy between the cultural skills of human beings and chimpanzees needs to be explained. (loc 5020)
He also surveys several putative answers, and finds them wanting. His remarks on Tomasello (loc 5046-5067) seem to me quite correct, noting that though Tomasello’s mind reading account might explain how culture might spread and its achievements retained cross generationally:
…it says little…about the initial spark that triggers cultural invention. No doubt the human species is particularly gifted at spreading culture – but it is also the only species to create culture in the first place. (loc 5067, his emphasis)
So what’s Dehaene’s proposal?
My own view is that another singular change was needed - the capacity to arrive at new combinations of ideas and the elaboration of a conscious mental synthesis (loc 5067).
This is quite a mouthful, and so far as I can see, what Dehaene means by this is that our frontal lobe got bigger and that this provided a “”neuronal workspace” whose main function is to assemble, confront, recombine, and synthesize knowledge” (loc 5089).
I don’t find this particularly enlightening. It’s neuro-speak for something happened, relevant somethings always involving the brain (wouldn’t it be refreshing if every once in a while the kidney, liver or heart were implicated!). In other words, the brain got bigger and we got culture. Hmm. This might be a bit unfair. Dehaene does say more.
He notes that the primate cortex, in contrast to ours, is largely modular, with “its own specific inputs, internal structure, and outputs.” Our prefrontal cortex in contrast “emit and receive much more diverse cortical signals” and so “tend to be less specialized.” In addition, the our brains are less “modular” and have greater “bandwidth.” This works to prevent “the division of data and allows out behavior to be guided by any combination of information from past or present experience.” (loc 5089)
Broken down to its essentials, Dehaene is here identifying the demodularization of thought as the key ingredient to the emergence of culture. As he notes (loc 5168), in this he agrees with Liz Spelke (and others) who has argued that the general ability to integrate information across modules is what spices up our thinking beyond what we find in other primates. Interestingly for my purposes here, Spelke ties this capacity for cross module integration to the development of linguistic facility (see here).
This assumption, that language is a necessary condition for the emergence of the kind of culture we see in humans is consistent with the hypothesis Minimalists have been assuming (following people like Tatersall (here)) that the anthropological “big bang,” which occurred in the last 25-50,000 years, piggy backed on the emergence of FL in the last 50-100,000 years. Moreover, it’s language as module buster that gets the whole amazing culture show on the road.
But what features of language make it a module buster? What allows grammar to “assemble and recombine” otherwise modular information? What’s the secret linguistic sauce?
Sadly, neither Dehaene nor Spelke say. Which is too bad as me and my lunch buddies (thx Paul, Bill) have discussed this question off and on for several years now, without a lot to show for it. However, let me try to suggest a key characteristic that we (aka I) believe is implicated. The key is syntax!
The idea is that FL provides a general-purpose syntax for combining information trapped within modules. Syntax is key here, for I am assuming (almost certainly wrongly, so feel free to jump in at any point) what makes information modular is some feature of the module internal representations that make it difficult for them to “combine” with extra-modular information. I say syntax for once information trapped within a module can combine with information in another module it appears that, more often than not, the combination can be interpreted. Thus, it’s not that the combination of modularly segregated concepts is semantically undigestible, rather the problem seems to be getting the concepts to talk to one another in the first place, and, I take this to mean, to syntactically combine. So module busting will amount of figuring out how to treat otherwise distinct expressions in the same way. We need some kind of abstract feature that, when attached to an arbitrary expression, allows it to combine with any other expression from any other module. What we need, in effect, is, what Chomsky called, an “edge-feature,” (EF) a thingamajig that allows expressions to freely combine.
Now, if you are like me, you will not find this proposal a big step forward for it seems to more name a solution than provide one. After all, what can EFs be such that they possess such powers? I am not sure, but I am pretty confident that whatever this power is it’s purely syntactic. It is an intrinsic property of lexical atoms and it is an inherited property of congeries of such (i.e. outputs of Merge). I have suggested (here) that EFs are, in fact, labels, which function to close Merge in the domain of the lexical items (LIs). In the same place I proposed that labeling is the distinctively linguistic operation, which in concert with other cognitively recycled operations, allowed for the emergence of FL.
How might labels do this? Good question. An answer will require addressing a more basic question: what are labels? We know what they must do: they must license the combination both of lexical atoms and complexes of such. Atomic LIs are labels. Complexes of LIs are labeled in virtue of containing atomic ones. The $64,000 question (doesn’t sound like much of a prize anymore, does it?) is how to characterize this. Stay tuned.
So, culture supervenes on language and language is the recycling of more primitive cognitive operations spiced with a bit of labeling. Need I say that this is a very “personal” (read “extremely idiosyncratic and not currently fashionable”) view? Current MP accounts are very label-phobic. However, the question Dehaene raises is a good one, especially for theories like MP that presuppose lots of cognitive recycling. It’s not one whose detailed answer is anywhere on the horizon. But like all good questions, I suspect that it will have lots of staying power and will provide lots of opportunities for fun conversations.