Freethought & Rationalism Archive

LiveFreeOrDie · 02-27-2002, 10:15 AM

In another thread, Oolon Colluphid wrote:

Quote:

...only about one in a hundred of the cells in your body is actually a human one.

Please explain. This sounds like the basis of a fantastic new diet.

Thanks,
LFOD

[ February 27, 2002: Message edited by: LiveFreeOrDie ]

bluefugue · 02-27-2002, 10:24 AM

I wondered about that too. Does he mean there are more bacteria in the human gut than there are cells making up the human body?

Kevin Dorner · 02-27-2002, 11:52 AM

He could as welll have said that 99% of our alleles are shared with other living things; ie genetically only 1% of our genes are exclusively human. I haven't heard that other statistic before though. That's a lot of bacteria... yech.

[ February 27, 2002: Message edited by: Kevin Dorner ]

Kosh · 02-27-2002, 02:03 PM

Quote:

Originally posted by IesusDomini:
I wondered about that too. Does he mean there are more bacteria in the human gut than there are cells making up the human body?

They did say something about this in the Missing
Link program last night (or maybe it was another
show). NOt sure if those were the numbers though.

As for Oolon being 1% human, we Scotts have
suspected as much about the Brits for eons..

KeithHarwood · 02-27-2002, 02:27 PM

Quote:

Originally posted by Kosh:


As for Oolon being 1% human, we Scotts have
suspected as much about the Brits for eons..

That's "Scots" if you don't mind and they are as British as the English. It's the English who are 1% human.

And I should know, I am English. My wife is Scots. Her ancestors earned their living by stealing cattle.

English cattle of course.

tronvillain · 02-27-2002, 05:27 PM

It's simple: the bacterial cells in and on your body outnumber the human cells a hundred to one, but that's not saying much.

theyeti · 02-27-2002, 07:40 PM

Quote:

Originally posted by tronvillain:
It's simple: the bacterial cells in and on your body outnumber the human cells a hundred to one, but that's not saying much.

Are you sure about that? If I remember, there's something like 5 billion bacteria in you, but hundreds of trillions of your own cells (something like 100 trillion in the brain alone, which is probably devoid of bacteria). Now if by "on you", you include that crud you dig out of your bellybutton, then it may be possible. But it's questionable whether or not that would be considered "you". Either way, I would be interested in seeing some numbers if anyone's got them.

theyeti

tronvillain · 02-27-2002, 09:23 PM

Here you go: <a href="http://www.bact.wisc.edu/Bact303/Bact303normalflora" target="_blank">The Bacterial Flora of Humans</a>.

Quote:

It has been calculated that the normal human houses about 10^12 bacteria on the skin, 10^10 in the mouth, and 10^14 in the gastrointestinal tract. The latter number is far in excess of the number of eukaryotic cells in all organs which comprise the human host.

I'm not sure if it's actually a hundred to one, but there do appear to be more bacterial cells than human cells. Of course, in terms of volume the bacteria are insignificant.

[ February 27, 2002: Message edited by: tronvillain ]

lpetrich · 02-27-2002, 11:15 PM

There are something like 100 trillion (10^14) "properly" human cells in our bodies (as adults, of course); so the number of intestinal bacteria is similar.

This estimate assumes an average cell size of 10 microns, which is reasonable; the average size of a bacterium is 1 - 2 microns, which implies a volume (and mass) 100 to 1000 times less.

Oolon Colluphid · 02-28-2002, 01:26 AM

Well, I thought this bit of my memory had tripped me up, so I did a quick trawl round the net.

From <a href="http://www.geocities.com/snowyssillyfacts/humans2.html" target="_blank">here</a>:

Quote:

The number of beneficial bacteria, or friendly flora, in the human intestine is equal to the amount of cells in a human body. Science, Feb.2, 2001

and

Bacteriologist Theodor Rosebury estimates that 10 million individual bacteria live on the average square centimeter of human skin, describing the surface of the body as akin to a "teeming human population during Christmas shopping".
(Source: a New Scientist 'Last Word', can't find it exactly)

<a href="http://www.hsc.wvu.edu/som/microguide/humanmicro.htm" target="_blank">The Human 'Microbial World'</a> gives a breakdown of the what and where of all these bacteria.

From <a href="http://www.cehs.siu.edu/fix/medmicro/normal.htm" target="_blank">Normal Flora</a>:

Quote:

Incredibly, our bodies are actually composed of more bacterial cells than human cells; while the human body is made up of about 1013 human cells, we harbor near 1014 bacteria.

The Science Frontiers Online article <a href="http://www.science-frontiers.com/sf125/sf125p04.htm" target="_blank">Tyrannies of the Tiny</a> says:

Quote:

We are only 10% human! The average human body contains 100 trillion cells, but only 1 in 10 of these cells is your own. The remaining 90% are bacteria. These alien organisms coat your skin and pave your inner passageways from mouth to anus. Of course they are much smaller than your own cells, so what you see is mostly you. Even so, you are a composite creature and cannot survive without these tiny hitchhikers and symbionts.

Just as in the oceans, our bodies are battlegrounds. Each day we are thrice invaded by massive new armies of bacteria present our food. Water and air, too, bring more combatants into the fray. Our resident bacteria continually fend off the invaders or accommodate them. Some are pathogenic and must be killed; others are useful in many ways, as in digestion.

Who's really in charge in our bodies: the 90 trillion bacteria or the 10 trillion cells we call our own? Probably, neither!

(Hamilton, Garry; "Insider Trading," New Scientist, p. 42, June 26, 1999.)

And <a href="http://www.madsci.org/posts/archives/dec96/840131722.Dv.r.html" target="_blank">this site</a> says that:

Quote:

The adult human body contains an estimated 1 * 10^14 cells (a 1 followed by 14 zeros..), 10% of which actually belong to us!! Thus, we have roughly 10 times more cells living in us than we do cells that make up our own bodies. Most of these 'outside' cells are bacteria living in the gastrointestinal tract. More than 400 species of microbes live in the colon alone, and can reach a density of 1 * 10^11 organism per milliliter of 'intestinal lumenal contents.'

I also read somewhere among the sites that 50% of our poo by dry weight is bacteria.

So it seems the 100:1 I'd remembered may have been an overestimate (though it doesn't look impossible. There's the same number of bacterial cells in our intestines as there is making up our whole bodies (50/50); another 40% of all the cells are bacteria on the skin, mouth, urinogenital and respiratory tracts. We are apparently only 10% human.

I'll amend my original post accordingly, though it hardly damages my point!

As to being only 1% human... being from a small planet somewhere in the vicinity of Betelgeuse, and not from Guildford after all (having hitched a lift here following Ford's bloody Guide entry -- it looked like a quiet place to write

)... what makes you think I'm human at all?

(

to Kosh)

Oolon

02-27-2002, 11:52 AM	#3
Kevin Dorner Senior Member Join Date: Dec 2001 Location: Toronto, Ontario, Canada Posts: 762	He could as welll have said that 99% of our alleles are shared with other living things; ie genetically only 1% of our genes are exclusively human. I haven't heard that other statistic before though. That's a lot of bacteria... yech. [ February 27, 2002: Message edited by: Kevin Dorner ]</p>

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02-27-2002, 10:24 AM	#2
bluefugue Veteran Member Join Date: Aug 2001 Location: Los Angeles Posts: 1,427	I wondered about that too. Does he mean there are more bacteria in the human gut than there are cells making up the human body?

02-27-2002, 05:27 PM	#6
tronvillain Veteran Member Join Date: Oct 2000 Location: Alberta, Canada Posts: 5,658	It's simple: the bacterial cells in and on your body outnumber the human cells a hundred to one, but that's not saying much.

02-27-2002, 11:15 PM	#9
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	There are something like 100 trillion (10^14) "properly" human cells in our bodies (as adults, of course); so the number of intestinal bacteria is similar. This estimate assumes an average cell size of 10 microns, which is reasonable; the average size of a bacterium is 1 - 2 microns, which implies a volume (and mass) 100 to 1000 times less.

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