In the general population, 75% are considered “tasters,” who experience a bitter taste of PTC, and 25% are non tasters. The non-taster effect is considered a recessive genetic trait. The “taster” trait is assigned to the “PTC gene” TAS2R38 discovered and so named in 2003. But this isn’t the only gene involved in bitter flavor, in fact over 30 genetic markers have been identified as involved in bitter taste. Nevertheless, the PTC gene is so reliable that it was used in paternity tests in the 1940s and onward until more complex DNA tests were invented. And the trait varies somewhat with ethnic origin, at least in Europe. Large studies performed in various countries of Europe (with N>100, as high as N>1000) found non-taster rates as high as 37% in Slovenia and as low as 16% in Uẑice, Serbia.
On the other hand, those other 30 genes certainly affect bitter taste as well. In a very small study (n=8), Henkin & Gillis (1977) served a pie made from the fruit antidesma bunius berries. Two people stated the pie was “extremely bitter and inedible.” The other six people found the pie “pleasant tasting, enjoyably edible and sweet.” The researchers then did the PTC test. The two people who found the pie bitter found PTC not bitter, whereas the other six people who thought the pie sweet turned up bitter on PTC. Obviously PTC tasting status had nothing at all to do with who thought those berries tasted bitter. Only eight people, well I guess by now we have a larger sample pool just on a 2014 New Amerykah pie. How many of you finished off your cake and how many put it away hoping for better days?
Maybe the whole business of what tastes bitter or sweet has something to do with childhood. Studies of babies have of course shown a preference for sweet tastes, and formula feeding versus breast feeding apparently merited enough study of effects for tastes later in life. In a study controlled for PTC gene variation, however, young children who were asked to taste items and then assign the bitter ones to Oscar the Grouch and sweet ones to Big Bird showed no racial or cultural differences between each other.
Interestingly, the children and mothers were studied with regard to bitter turning sweet, what we tea drinkers might consider “huigan.” Apparently this aspect of bitter tasting is also genetic. The researchers did conclude that children may be more alike to one another, because the children differed less from one another than they did from their mothers. Why then did children differ from their mothers? The study was inconclusive as to whether development of taste is affected by aging or by what is called “forced experience.” That is, the idea that we develop tastes based on what we are given to eat with no choice involved. In that theory, eventually we develop our adult taste preferences based on what our parents gave us to eat when young.
I can certainly see this effect in my own family. My mother cooked plain meat and served raw vegetables most days. (She was an Adele Davis mom, and in truth really wasn’t much of a cook). When my father remarried, I couldn’t adjust to my stepmother’s heavy sweet gravies and casseroles. In turn, I served my son plain meats and fish with raw vegetables, and his taste as an adult remains the same. My relatives complained he wouldn’t eat the casseroles and gravies when he visited. But my son still eats raw vegetables of all sorts daily with relish, and only reluctantly will eat cooked veggies even at the age of 25 when supposedly his taste should “mature.” I prefer mine raw or steamed lightly as well. To a large extent, two generations of my family are affected by the “forced experience” of one person.
But let’s go back to the berry pie. Why would one person decide that pie tastes sweet and delicious, and another person can’t stand to eat it, especially when PTC taster status did not factor into the conclusion? The truth is taste is complex, and if bitter taste truly involves 31 genes, the factors play out in such a confusion of individual differences that perhaps calling taste “subjective” is functionally the most useful. How useful is it to say “well my taste here is due to my 31 genetic markers?” even though such a statement is certainly quite “objective.”
An interesting theory I read is that the development of sour and bitter taste may have something to do with specific environmental adaptations designed to identify poisonous plants and avoid them. We know that plants develop bitterness as a way to protect themselves from insects. So perhaps my idea of sour or bitter is connected with not eating that poison sumac in the yard (though I rather relish the stick marrow). But my poison sumac may not grow where you live, and you have something else you must avoid eating in your yard.
Actually, if this theory holds true, the plants I’m truly evolved to avoid must be in northern or eastern Europe, rather than the Americas, because I’m only a second generation born here. Two generations isn’t really long enough for my genes to mutate very much. My sister had her DNA profile done and assuming she is truly my sister I can confirm from her results that I have the ability to taste pickle vinegar, I have a lactose enzyme which means I can digest and enjoy bovine milk, and I can smell asparagus in urine. And we learned that my grandfather was only 76% Ashkenazi which means somebody fooled around at some point without telling anyone, and subsequently everyone conveniently forgot.
In other words, we may believe we have an ethnic or genetic experience that guess what, we may not truly have. My sister swore she is lactose intolerant, one of the reasons she wanted a genetic test done. But in fact she carries the digestive gene, so her problems with milk must be due to another reason. This has to dampen pronouncements across the board that cow’s milk is bad. We do know that persons of Asian descent may lack the lactose enzyme, but this doesn’t mean we can conclude milk is poison or bad for the body if some people have a real ability to digest it. In like fashion, I don’t know if bitter taste is related to a skill of detecting poisons in one’s ancestral setting, but when considering the lactose enzyme, at least some environmental adaptation seems like a reasonable theory to me. One wonders with all the movement of people these days, how adaptations like taste will evolve in new directions in a few hundred years, and how difficult running a restaurant might be at that point because so many variations in taste live side by side.
Of course this is a tea blog so you all know where this is heading. Most tea blog readers are asking a question of a tea review: should I buy it?
While taste is not entirely subjective, the objective factors are surely confounding enough to make them functionally subjective, in the end, when reading “advice” from supposed experts. I think enough evidence here suggests that you can buy what you like without apology. You don’t have to like sheng. You don’t need to appreciate shou. One person’s gyokuro is another’s soggy wet spinach. And one man’s fabulous first steeping is another man’s tossed storage brew. Nobody needs to apologize for their happiness with Lincang tea, or for their distaste of smoky tuos or spore-filled heicha. For sure one person’s dry storage is another person’s musty wet basement.
People shouldn’t feel inferior because they are not on the “Sheng train.” You can adore your First Flush Darjeeling and ignore anyone who complains. Beautiful, yes stunning teas of every sort are ours to buy these days. If you get a tummy ache from a tea, why keep drinking it? Buy another tea that makes you feel happy and relaxed. And nobody else’s 31 genes can tell you that yours aren’t experienced enough, or sophisticated enough, sensitive enough or appreciative enough because that tea tasted like crap. Your opinion is what matters, anything else is group think.
And you don’t have to buy it. Unless you want to.
Requiescat in Pace