
Scientists bust myth that our bodies have more bacteria than human cells - etiam
http://www.nature.com/news/scientists-bust-myth-that-our-bodies-have-more-bacteria-than-human-cells-1.19136
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dang
[https://news.ycombinator.com/item?id=10871694](https://news.ycombinator.com/item?id=10871694)

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toufka
So there are 39 trillion bacterial cells in a human body, and ~30 trillion
'human' cells in our body. EXCEPT that 25 of the 30 trillion human cells in
our body don't even have any human DNA in them (red blood cells lack a
nucleus, cannot divide, and do not contain human genetic information).

So depending on how you draw the line there are 39 trillion non-human nuclei
in a human body, and only 5 trillion human nuclei. That brings our non-
human:human genetic ratio right back to 10:1. Though that too is misleading
given the amount of DNA in each of those nuclei. (human cells have
significantly more DNA in their genome than bacterial cells)

These headlines are ridiculous.

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InclinedPlane
Bacteria don't have nuclei.

Also, you could enlist the population of mitochondria to weigh against
bacteria if you really wanted to.

~~~
toufka
Yep - you're correct, bacteria do not have a nucleus either. I was swapping
the words around to try and create a parallel sentence and I thought I had
corrected 'nuclei' to 'genomes' in my edit, but apparently I did not.

"there are 39 trillion separate non-human genomes in a human body, and only 5
trillion human nuclei." And you'd be correct in pointing out that that
sentence is also a little wonky.

Which is the best metric? Nuclei, cells, dividable cells, base pairs, non-
redundant base pairs, protein-encoding base pairs, expressed human protein,
mass, species, etc?

It's difficult to get the nomenclature exactly parallel between mammalian and
bacterial cells, much less fungal or viral material. But that's also the
point. It's tricky to compare, and shouting that one comparison is _wrong_ is
just kind of click-baity.

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timrpeterson
Money quote at the end:

> “It is good that we all now have a better estimate to quote,” says Peer
> Bork, a bioinformatician at the European Molecular Biology Laboratory in
> Heidelberg, Germany, who works on the human and other complex microbiomes.
> “But I don’t think it will actually have any biological significance.”

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siyer
See also: Ed Yong in The Atlantic, who has a nice story on this that includes
some rather fun sentences [1]:
[http://www.theatlantic.com/science/archive/2016/01/youre-
pro...](http://www.theatlantic.com/science/archive/2016/01/youre-probably-not-
mostly-microbes/423228/)

[1] Such as: "In 2014, Judah Rosner from the National Institutes of Health
drew attention to this “fake fact” in a letter to Microbe magazine. More
recent estimates, he noted, put the total number of human cells at anywhere
from 15 trillion to 724 trillion, and the number of gut microbes at anywhere
between 30 trillion and 400 trillion. Which gives a ratio that can best be
expressed as ¯\\_(ツ)_/¯."

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lifeisstillgood
Myths need busting when the myths are misleading. The _idea_ hat there _about_
as many bacteria cells in me as there are human cells in me is not misleading
(whether it is less, more or order of magnitude more is not relevant) - it's
the fact that I have a Eco-system of bacteria in and on me and recognising
that is valuable

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jkldotio
"the researchers produce a ratio for microbial to human cells for the average
man of 1.3:1, with a wide uncertainty"

Even given a "wide uncertainty" their estimate is still on the side of the
microbial cells. That hardly warrants a headline saying "scientists bust myth"
as the "myth" was often just phrased as a "there are more" not as a specific
ratio of 10:1.

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13of40
Hemoglobin molecules are still only 0.04% iron though, right?

