Gene Expression

A world of sensory difference

Do you smell what I smell? Perhaps not, and it might not be due to a cold…Genetic variation in a human odorant receptor alters odour perception (Nature):

Human olfactory perception differs enormously between individuals, with large reported perceptual variations in the intensity and pleasantness of a given odour…A common variant of this receptor (OR7D4 WM) contains two non-synonymous single nucleotide polymorphisms (SNPs), resulting in two amino acid substitutions (R88W, T133M; hence ‘RT’) that severely impair function in vitro. Human subjects with RT/WM or WM/WM genotypes as a group were less sensitive to androstenone and androstadienone and found both odours less unpleasant than the RT/RT group. Genotypic variation in OR7D4 accounts for a significant proportion of the valence (pleasantness or unpleasantness) and intensity variance in perception of these steroidal odours. Our results demonstrate the first link between the function of a human odorant receptor in vitro and odour perception.


I’ve posted on sensitivity to taste and variation many times: PTC taste, balancing selection?, PTC, part II, Taste & behavior genetics, Genetics of taste and Slow & diverse food. We know that taste & smell tend to operate syngergistically, so variation along both sensory dimensions no doubt would increase the range of human variation on this phenotype due to the increase in the number of combinations. It might make us reflect on the role that critics of food & wine play in terms of how they serve as filters to other people when perception itself might differ so much from person to person.

Here’s a some data on the polymorphism from the HapMap.

Related: Nature News has an article up. Also, Science Daily.

Comments

  1. #1 Mo
    September 17, 2007

    Try holding your nose next time you eat, and you’ll see that you can’t taste something properly without smelling it.

  2. #2 Nina P
    September 17, 2007

    I believe I am a supertaster – grapefruit is inedibly bitter, I dislike the taste of alcohol enough to avoid it despite its social benefits, I don’t like coffee, etc. The wikipedia article on supertasters and most other articles imply the main difference between supertasters and others is a higher concentration of taste buds. But how could that explain the particular sensitivity to bitterness? If normal tasters don’t taste the bitter compounds at all, it doesn’t mean they have fewer receptors, it means they have none, right? Surely it’s more complicated than the number of tastebuds? Some people (not me, thank doG) can’t stand the taste of cilantro, but don’t otherwise qualify as supertasters, for example.

    When I first visited Malaysia at age 20 I had every incentive to increase my tolerance of chili heat, which I did. Capsicum registers as a physical sensation on the skin of the mouth, more than a flavor. With practice I was able to “buff up” in order to taste the other delicious flavors behind the heat (galangal, lime, cilantro, etc.) In contrast, I’ve tasted a lot of booze, but I’ve never been able to warm up to the flavor.

    I also have an acute sense of smell, noticing odors my companions can’t discern. Wikipedia says more women are supertasters, and we know colorblindness is far more common in men. I expect women tend towards more acute odor perception, too.

  3. #3 razib
    September 17, 2007

    Try holding your nose next time you eat, and you’ll see that you can’t taste something properly without smelling it.

    as someone with severe allergies, all i can say is welcome to my world!

    I believe I am a supertaster – grapefruit is inedibly bitter, I dislike the taste of alcohol enough to avoid it despite its social benefits, I don’t like coffee, etc.

    go to a local high school and see if can get some PTC paper. pass it around your family. if supertasters have two copies of the tasting allele then it should be issue to construct a pedigree.

  4. #4 TGGP
    September 17, 2007

    I’m with you Razib. The upside is you don’t have to go for gourmet since bargain stuff isn’t much different. Part of that is just my general philistinery though.

  5. #5 agnostic
    September 17, 2007

    I don’t know, TGGP, we supertasters can really taste the prole-y goodness of a Whopper, for example. I’d kill for one right now.

  6. #6 purple and yellow floral pattern pillow
    September 17, 2007

    One thing I have noticed is that the new energy drinks coming out vary a lot in terms of how palatable people find them. For example, some supertasters seem to really like Monster, but I find it insipid.

  7. #7 agnostic
    September 18, 2007

    some supertasters seem to really like Monster

    Word up! Although I’ve never tried any others, so I can’t say how it compares. But when you find something good, why waste time sampling the other 34548960879264397 types out there?

  8. #8 Sandgroper
    September 19, 2007

    Alcohol has social benefits?

  9. #9 Rob
    September 19, 2007

    As I recall, inability to taste PTC correlates with IQ. I’m a taster btw. Also, tasters eat fewer vegetables, which could be a gene-environment interaction affecting IQ.

  10. #10 Nina P
    September 20, 2007

    Alcohol has social benefits?

    Hellz yeah. Drinking makes you funnier and more attractive, right?

    tasters eat fewer vegetables

    Tasters may eat a smaller variety of vegetables, but even non-tasters may avoid certain foods for other reasons – like cilantro-haters, whose distaste appartently has something to do with enzymes. I don’t eat “bitter greens” (why do they even exist?!) or endive, but I eat a lot of other non-bitter vegetables.

  11. #11 Rob
    September 20, 2007

    Someone must like bitter greens. Maybe just moms.

    Intelligence and personality related to tasting
    http://www.springerlink.com/content/n411121322hj361l/

    Nontasters have higher visuospatial ability. If I remember correctly, micronutrient supplementation disproportionately raises performance IQ.

    Tasting and vegetable consumption
    http://www.ajcn.org/cgi/content/full/84/1/245

    Vegetable consumption and IQ
    http://pediatrics.aappublications.org/cgi/content/full/119/1/e38

    Granted, these aren’t the last word on the relationship. The last one in particular can not provide a chain of causation. But it is an interesting possibility.

  12. #12 Sandgroper
    September 21, 2007

    Nina, trust me – never try eating Chinese hairy melons.

    Sounds like the guys I used to know who swore they drove better after a few beers. Nope. OK, I’m boring, I know I am.