Neurogastronomy, neuroenology, neuroneuroscience – does it actually tell us anything?

I should think that we are all pretty well aware of the trend to neuroify pretty much everything (neuroaesthetics, neuroeconomics, uh neuroecology). In a review of Gordon Shepherd’s book Neuroenology: How the Brain Creates the Taste of Wine, Steven Shapin spends some time ruminating on whether there is any actual use to all of this.

First, some comments on the ‘neuroenology’:

The distinctions between olfaction and gustation, and even between orthonasal and retronasal olfaction, are only a start. There are many more scientific facts to be understood about, for example, how wine moves around in the buccal cavity and then on to the pharynx and esophagus; how these muscle- and gravity-induced movements contribute to sensory experience; how swallowing is controlled by the sCPG (the swallowing central pattern generator); how swallowed wine leaves behind in the mouth and pharynx both a sticky “matrix” and “volatiles” which can be released when post-swallow respiration resumes; how the first expiration of breath after swallowing has the highest concentration of volatiles, which some tasters call “the aroma burst” and which they consider “the strongest contributor to the taste of wine”; how the nerves of the tongue and nasal epithelium are arrayed and what paths they take to the brain; how and where the various sensory modes are integrated into the experience of flavor; and how some aroma molecules come to elicit olfactory responses…

But: does it actually change how we perceive wine? Can it be used to broaden or deepen our appreciation for wine (or food in general)?

So does any of this newly acquired “objective” knowledge about sensory modes bear at all on the nature and quality of subjective experience? Yes, it may, and no anti-reductionist humanist should feel obliged to deny that. Nevertheless, some claims for the aesthetic significance of scientific knowledge seem dubious. For example, Shepherd writes about the importance of the mucus membranes in the mouth, assuring us that “being aware of the structure of the mucus membranes, their various receptors, and the sensations they produce will enrich the wine-tasting experience.” But other neuroscientific stories seem more plausibly experience-changing. Scientists’ accounts of the retronasal pathway, for example, have the capacity to alter the attention paid to different types of olfactory experience. Our senses engage with a field of potential experience: we can attend to some features of that field and not to others, making some sensible aspects part of our focal awareness, and backgrounding or bracketing others. Having a “private” conversation in a public room, we focus on our partner’s talk and not on the booming, buzzing “background” sound washing over us. Then we overhear someone mentioning our name and we realize that the background noise has been waiting to be turned into signal through a change in attentiveness…

Michael Baxandall’s marvelous accounts of what he called “the period eye” in Quattrocento painting told us how late medieval people looked at paintings — the eye attending to the areas of azure and gold in the Virgin’s clothing, guided there because of the known preciousness and expense of these pigments, just as the Quattrocento period eye attended to certain shapes because of the widely distributed mercantile skill in gauging the internal volumes of barrels from their visible surfaces. Knowing this, you can look at paintings in this way too. The French sociologist Antoine Hennion — also a wine lover — has proposed a “sociology of attention” in which features of the sensory field are framed, parsed, and differently stressed, and in which subjects momentarily make themselves passive with respect to the sensed object. (“Ah, yes, now I notice that.”) So the framing impulses that can change or enhance sense experience need not derive from sensory science, and in these cases they do not, but sensory framing may come from scientific accounts of the structures and processes of sense perception. Neuroenology relates several stories that do have the capacity to change — to reframe, to reconstitute — our sensory experience. It’s an authentic debt that some pleasures might owe to some scientific accounts…

Then there are neuroscientific accounts of what areas of the brain “light up” in functional magnetic resonance imaging (fMRI) when laboratory animals sniff different volatile substances. Neuroscientists also tell us that when you — but not, in this case, laboratory animals — are told that one of two wines you’re drinking costs more, even when the wines are in fact the same, a different area of the cortex lights up for the “expensive” wine, and does so more brightly. Yet both of these findings bear as much relationship to the experience of aroma as knowing the location of the fuel pump does to the experience of driving a car: the pump and the brain area relating to odor have got to be somewhere, but knowing where they are doesn’t add to, subtract from, or change the experiences of driving or drinking.

Finally, a note on neuromania:

[T]he Italian psychologists Paolo Legrenzi and Carlo Umiltà have called “neuromania.” This is the tendency to go beyond identifying the neural bases for beliefs and sensations to the claim that beliefs and sensations really are their neural bases. The first claim is unexceptionable: of course, sensations are the result of interactions between our neural structures and things in the world and elsewhere in our bodies. In this sense, neuroscience has begotten a set of pleonasms — using more words than necessary to convey a specific meaning — and these pleonasms have metastasized through contemporary culture. Insofar as our mental life is neurally based — and who now doubts that? – neuro-whatever might just be a potentially useful way of reminding us of this fact: “neuroaesthetics” is aesthetics; “neuroethics” is ethics; “neuromarketing” is marketing; “neuroeconomics” is economics — even if traditional practitioners of aesthetics, ethics, and the like have not routinely had much to say about which areas of the brain “light up” when we see a beautiful painting, do a good deed, or buy a new car, and provided that we appreciate that what “goes on in the brain” includes what people know, remember, feel, and feel to be worth their attention.

 

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Neanderthal neurograstronomy

There is a genetic basis to the food that we enjoy eating. Some people – which I call strange people – think cilantro has a strange, soapy taste at least partially because of a particular polymorphism in a odor receptor gene (OR6A2).

soapy cilantro

The question of why we enjoy certain foods and flavors is not solely a genetic one, but also a conceptual one. Take the questions of why we like spicy food. Other animals do not: they will eat spicy food but would rather prefer not to, thanks. If you ask people what the best spiciness level is, they will tell you that it is whatever is right below their pain threshold. A smidgen too much and it is unbearably hot. A smidgen too little and it is bland as they come. The molecule that gives something its spiciness is capsaicin which stimulates the same receptors that give information about the warmth of food. It is possible, then, that this is a byproduct of our adaptation to prefer cooked food. Food that has been roasted is digested more quickly and provides more calories.

But knowledge of genetics can give us insight into those we do not have direct experience with. We now have genomic sequence data from one Denisovan and two Neanderthals. Do they experience food similarly to modern humans?

In many ways, yes. One change that probably occurred after the invention of cooking is a reduction in certain masticatory muscles. Once you can cook, your needs to chew really really hard are reduced. And a gene responsible for this, MYH16, is expressed in chimpanzess (no fire) but not in humans (plenty of fire). It turns out that MYH16 is also not expressed in the Denisovan and Neanderthal samples.

We can also look at a taste receptor, such as TAS2R38 which responds to phenylthiocarbamide (PTC). This is a flavor that, depending on your genetic makeup you either cannot taste at all, or that tastes very bitter. There is variation across populations: 98% of people indigenous to the Americas can taste it while only 42% of those indigenous to Australia and New Guinea cannot. Interestingly, chimpanzees can also taste it but they do so in a different manner.

None of the Denisovan or Neanderthals had the human mutation that allowed PTC-tasting. But that shouldn’t stop them from tasting it: one of the Neanderthals had a different mutation from either humans or chimpanzees on the gene. This is convergent evolution at work, people.

Even more interestingly, the AMY1 is a gene responsible for the enzyme that starts the digestion of starch. Starch is responsible for something like 70% of the calories in human agricultural population. The more copies we have of this gene, the more of the enzyme we have in our saliva. Chimpanzees have two copies: humans have around 6 or 7 of them. And these Denisovans and Neanderthals? Only two!

You are what you eat, and what you eat is influenced by what you are. It’s pretty fun that we can get at what a Neanderthal enjoyed eating by looking at the genetics of their taste receptors…

References

Perry, G., Kistler, L., Kelaita, M., & Sams, A. (2015). Insights into hominin phenotypic and dietary evolution from ancient DNA sequence data Journal of Human Evolution DOI: 10.1016/j.jhevol.2014.10.018