

Your Ethnicity Determines the Species of Bacteria That Live in Your Mouth - clarkm
http://blogs.smithsonianmag.com/science/2013/10/your-ethnicity-determines-the-species-of-bacteria-that-live-in-your-mouth/

======
tzs
The most interesting fact I've read about the bacteria that live on us is that
the populations on our hands differ.

The average hand has about 150 different species, with only about 17% of those
also appearing on the other hand of the same person. [1]

[1] [http://msms.ehe.osu.edu/2012/02/29/how-many-bacteria-
species...](http://msms.ehe.osu.edu/2012/02/29/how-many-bacteria-species-can-
coexist-on-a-single-hand-and-do-girls-really-have-cooties/)

------
mbubb
Fascinating.

This is different than I thought: "The variation along ethnic lines, they
believe, is a reflection of genetics, not environment."

Taking one example that I know a little about. Korea. I would think that
environmental impact would include things like the type of probiotic foods
they eat - like kimchi, fermented soybeans and fermented fish would affect the
flora and fauna in their mouth.

Also eating habits - Koreans will often share a soup container and side dishes
where everyone sticks their chopsticks and soupspoons into a shared pot,

These things would affect the types of bacteria in their bodies I would
think...

------
jostmey
Here is the source:
[http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjourna...](http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0077287)

~~~
a_bonobo
Thanks for the paper!

So only 4 US ethnicities were tested: African Americans, Caucasians, Chinese
and Latinos. That feels extremely broad - especially "Chinese" and "African
Americans" combine many, many different genetic groups. Edit: The Chinese
government, for example, recognizes 56 ethnic groups, which may or may not
genetically be distinct.

>The subgingival microbial community was able to predict an individual’s
ethnicity with a 62% accuracy, 58% sensitivity and 86% specificity.

Wait, that doesn't seem very good - I could flip a dented coin and get similar
results?

~~~
sgt
What's with the popular usage of latino or hispanic as a separate race?

From wiki: "The United States Census uses the ethnonym Hispanic or Latino to
refer to "a person of Cuban, Mexican, Puerto Rican, South or Central American,
or other Spanish culture or origin regardless of race."

Also, remember that there are many white/caucasian people in Mexico and other
latin american countries that also are hispanic. Ricky Martin is an obvious
example of a white Puerto Rican, for instance.

I am not saying a mestizo should necessarily be classified as "white", but
there seems to be an idea these days that hispanics are a separate race, which
is incorrect.

~~~
skoob
In general "race" is a bogus term. Usually, when people (especially Americans)
use the word race, they actually mean something closer to ethnicity.

------
fragsworth
They're not sure whether this stems from genetics or environment - they say
they _think_ it's genetics, but there might be a simple environmental
explanation:

The main way people exchange mouth bacteria is through dating, and there's a
huge tendency to date people of similar ethnicity.

~~~
humannature
It's human nature, it's in our DNA. People like to hang out w/ those that look
like them, they feel more comfortable. Yes there are outliers here and there,
but for the most part, I can bet 70%+ of the people reading this are as
follows: if you are Asian, I bet most of your good friends are Asian, if you
white, then most of your good friends are white, and so on and so forth. It's
not racism, it's just human nature that starts early on. If you grew up in
America you know what I'm talking about, ever notice how young kids including
yourself start naturally forming groups late in elementary school? if not then
definitely around middle school. Whites hang out with the whites, Asians hang
out with the Asians, Latinos w/ Latinos, blacks w/ blacks, etc..

~~~
prawn
I don't think that was being questioned at any point. The comment is about
whether people share similarities in their microbiome because of their genetic
background or because they hang around with people generally of the same
background.

------
auctiontheory
I wonder how (if at all) this might be tied to recent findings about gut
bacteria and obesity.

We're still just scratching the surface in terms of our understanding of the
human body. Doctors in 2113 will be as horrified by some of our early 21st
century medical practices and recommendations as we are of the Downton Abbey
era of medicine.

------
Alex3917
This doesn't surprise me. People of different ethnicities smell subtly
different, which either comes from the bacteria or else it means there are
different chemicals available to the bacteria, probably both.

~~~
error54
I'd say everyone smells subtly different and it has nothing to do with
ethnicity; A dog can easily differentiate between people by sheer smell alone.

------
kordless
Does this imply I can eventually login with my breath?

kord@brush:~$ ssh -i .ssh/id-halitosis teeth

------
rdl
Wow, that's unexpected -- I would have expected diet to the primary
determinant.

~~~
gojomo
Diet might still be major: they say their predictive model got ethnicity right
62% of the time, from the bacterial info. I suspect that you could also
predict ethnicity better than chance from diet logs.

To really tease out the genetic influence, you'd want to standardize diet,
_and_ give all strains equal chance to colonize. Perhaps, compare cohabiting
similar-diet same-sex kissing-partners of different-ethnicities, after an
initial palate-cleansing course of antibiotics? It's the only way to be sure!

