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Why Does Cilantro Taste Like Soap To Some People?

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by Sophie Harrington

Surprisingly controversial, cilantro (or coriander, as it's known in other parts of the world) has sparked a level of vitriol unheard of amongst other herbs. From the online community at IHateCilantro.com to the “I hate coriander. Worst herb ever” Facebook group, it might be the most polarizing leaf in the culinary world. What is it about cilantro that makes some people describe it as tasting like soapy pennies, moldy shoes, and cat pee, while others rave about its fresh flavor?

Despite being well liked in many other cultures, cilantro has historically been a controversial herb in the western kitchen. It produces a specific subset of aldehydes, organic compounds that can provide highly pungent odors when highly expressed. It’s these aldehydes that are most likely responsible for the soapy taste and smell many people associate with cilantro. Yet these aldehydes also provide the fresh, citrusy aroma that others rave about. So why are some people unable to taste the good side of cilantro?

Disliking cilantro isn’t a recent phenomenon. In a 2001 paper, University of Otago anthropologist Helen Leach found that cilantro was treated as an unwanted herb in European cuisine from the 16th century onward, and very often disparaged for its foul taste and smell.

Leach suggests that this dislike may have stemmed from a misleading interpretation of the word’s etymology, itself stemming from the Greek koris, for bug. Sharing a similar shape to bedbugs, the newly unpopular herb may have been associated with their foul smell. This negative association may have been enough to enhance the less palatable flavors in cilantro, leading Victorians to turn their noses up at the herb.

The use of cilantro in many non-western forms of cooking may have fed into long-standing European stereotypes. By associating cilantro with unclean, fetid bedbugs, many forms of non-western cuisine were tarred in association. It was not until after World War II, when it became fashionable to try new cuisines at restaurants and even branch out in the kitchen at home, that cilantro begin to re-enter the western culinary canon.

A study by Lilli Mauer and Ahmed El-Sohemy at the University of Toronto found that while 17 percent of Caucasians disliked the taste of cilantro, only 4 percent of Hispanics and 3 percent of people of Middle Eastern descent disliked the herb. Mexican cuisine, for example, is known to make full use of the herb and it's a staple spice in many Middle Eastern and South Asian cuisines, too. These groups similarly appear to be those least likely to dislike it. Perhaps growing up eating cilantro is enough to gain immunity to its less palatable aromas and tastes.

This might seem like vindication to those who suggest a dislike of cilantro is just being fussy, but more recent studies have found specific genetic differences associated with the taste. A study by the personal genomics company 23andMe identified a small DNA variation in a cluster of olfactory receptor genes that is strongly associated with the perception of a “soapy” taste in cilantro. This may be traced to the OR6A2 gene, an olfactory receptor able to bind many of the aldehydes implicated in the herb's very particular smell. Perhaps those with a specific variation in the gene are particularly sensitive to its soapiness.

Studies on twins have also bolstered the suggestion that cilantro preference has a genetic component. Preliminary research by Charles Wysocki at the Monell Chemical Senses Center suggests that while 80 percent of identical twins share similar taste profiles for cilantro, only 42 percent of fraternal twins do. If the genetic component does play a significant role, it may be that certain cultures are predisposed to use cilantro in the cooking because they’re genetically predisposed to like it, rather than the other way around.

That’s some good news for cilantro-phobes at least, since no one can blame you for your genes. Still, it doesn’t make the horror of accidentally getting a bite of the green stuff any more bearable for them.

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Big Questions
How Are Speed Limits Set?
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When driving down a road where speed limits are oppressively low, or high enough to let drivers get away with reckless behavior, it's easy to blame the government for getting it wrong. But you and your fellow drivers play a bigger a role in determining speed limits than you might think.

Before cities can come up with speed limit figures, they first need to look at how fast motorists drive down certain roads when there are no limitations. According to The Sacramento Bee, officials conduct speed surveys on two types of roads: arterial roads (typically four-lane highways) and collector streets (two-lane roads connecting residential areas to arterials). Once the data has been collected, they toss out the fastest 15 percent of drivers. The thinking is that this group is probably going faster than what's safe and isn't representative of the average driver. The sweet spot, according to the state, is the 85th percentile: Drivers in this group are thought to occupy the Goldilocks zone of safety and efficiency.

Officials use whatever speed falls in the 85th percentile to set limits for that street, but they do have some wiggle room. If the average speed is 33 mph, for example, they’d normally round up to 35 or down to 30 to reach the nearest 5-mph increment. Whether they decide to make the number higher or lower depends on other information they know about that area. If there’s a risky turn, they might decide to round down and keep drivers on the slow side.

A road’s crash rate also comes into play: If the number of collisions per million miles traveled for that stretch of road is higher than average, officials might lower the speed limit regardless of the 85th percentile rule. Roads that have a history of accidents might also warrant a special signal or sign to reinforce the new speed limit.

For other types of roads, setting speed limits is more of a cut-and-dry process. Streets that run through school zones, business districts, and residential areas are all assigned standard speed limits that are much lower than what drivers might hit if given free rein.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Do Bacteria Have Bacteria?
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Drew Smith:

Do bacteria have bacteria? Yes.

We know that bacteria range in size from 0.2 micrometers to nearly one millimeter. That’s more than a thousand-fold difference, easily enough to accommodate a small bacterium inside a larger one.

Nothing forbids bacteria from invading other bacteria, and in biology, that which is not forbidden is inevitable.

We have at least one example: Like many mealybugs, Planococcus citri has a bacterial endosymbiont, in this case the β-proteobacterium Tremblaya princeps. And this endosymbiont in turn has the γ-proteobacterium Moranella endobia living inside it. See for yourself:

Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)
Fluorescent In-Situ Hybridization confirming that intrabacterial symbionts reside inside Tremblaya cells in (A) M. hirsutus and (B) P. marginatus mealybugs. Tremblaya cells are in green, and γ-proteobacterial symbionts are in red. (Scale bar: 10 μm.)

I don’t know of examples of free-living bacteria hosting other bacteria within them, but that reflects either my ignorance or the likelihood that we haven’t looked hard enough for them. I’m sure they are out there.

Most (not all) scientists studying the origin of eukaryotic cells believe that they are descended from Archaea.

All scientists accept that the mitochondria which live inside eukaryotic cells are descendants of invasive alpha-proteobacteria. What’s not clear is whether archeal cells became eukaryotic in nature—that is, acquired internal membranes and transport systems—before or after acquiring mitochondria. The two scenarios can be sketched out like this:


The two hypotheses on the origin of eukaryotes:

(A) Archaezoan hypothesis.

(B) Symbiotic hypothesis.

The shapes within the eukaryotic cell denote the nucleus, the endomembrane system, and the cytoskeleton. The irregular gray shape denotes a putative wall-less archaeon that could have been the host of the alpha-proteobacterial endosymbiont, whereas the oblong red shape denotes a typical archaeon with a cell wall. A: archaea; B: bacteria; E: eukaryote; LUCA: last universal common ancestor of cellular life forms; LECA: last eukaryotic common ancestor; E-arch: putative archaezoan (primitive amitochondrial eukaryote); E-mit: primitive mitochondrial eukaryote; alpha:alpha-proteobacterium, ancestor of the mitochondrion.

The Archaezoan hypothesis has been given a bit of a boost by the discovery of Lokiarcheota. This complex Archaean has genes for phagocytosis, intracellular membrane formation and intracellular transport and signaling—hallmark activities of eukaryotic cells. The Lokiarcheotan genes are clearly related to eukaryotic genes, indicating a common origin.

Bacteria-within-bacteria is not only not a crazy idea, it probably accounts for the origin of Eucarya, and thus our own species.

We don’t know how common this arrangement is—we mostly study bacteria these days by sequencing their DNA. This is great for detecting uncultivatable species (which are 99 percent of them), but doesn’t tell us whether they are free-living or are some kind of symbiont. For that, someone would have to spend a lot of time prepping environmental samples for close examination by microscopic methods, a tedious project indeed. But one well worth doing, as it may shed more light on the history of life—which is often a history of conflict turned to cooperation. That’s a story which never gets old or stale.

This post originally appeared on Quora. Click here to view.

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