If you’ve had the pleasure of attending a microbiology or human microbiome talk within the last year, you’ve likely heard the following statistic: there are ten times as many bacteria in your body then there are eukaryotic cells. It’s an astounding fact that we cling to and regurgitate to impress our friends and make a splash at parties. But is it true? If you want to double check the math, go to the start.

From one source to another, I followed the rabbit hole of reviews and papers to find at the end of this journey a pair of papers by Dobzhansky, T and Lukey, D. Two publications published in the early 1970s which made estimates of the number of bacterial and eukaryotic cells based on weight. The eukaryotic estimate of 1013 cells, I could not track down. The paper was not available in electronic format. Luckily the bacterial estimate made by Lukey, D. et al is easily assessable. The statement in question was made in the opening remarks of the second International Symposium on Intestinal Microecology:

“The composition of this system is surprising. Adult man carries 1012 microbes associated with his epidermis and 1014 microbes in his alimentary tract (Fig. 1). The latter number is based upon 1011 microbes/g contents of an alimentary tract with a capacity of approximately 1 liter. The 1013 cells (2) in his body are a distinct numerical minority of the total being that we call man.”  – T. D. Luckey. Introduction to intestinal microecology. The American Journal of Clinical Nutrition 25:  1972, pp. 1292-1294.

Figure 1, if you’re curious, is a drawing of man with an arrow pointing to his gut aptly labelled “Alimentary Tract: 1014 Bacteria”.  

I am not doubting the validity of the statement or the calculations of the original authors. Instead, I want to bring to light the inevitable problem that arises when you propagate citations from one paper to another. The original message runs the risk of being lost or misinterpreted. Sadly, this is not an isolated incident and I have been on this garden path before. I have found citation which are overly vague, unrelated to the direct conclusion of the original paper, or rely on an interpretation of the data that is either written in speculation or never made at all. Propagating citations in this manner is potentially destructive to the scientific process so the next time you cite a paper which cited another, make sure to double check their statements.

The following two tabs change content below.

Yuriy Baglaenko

Founding Editor
Yuriy is a 4th year PhD student studying the suppression of autoimmunity at the University of Toronto. He is an avid musician with an at-home amateur recording studio and a mediocre intramural volleyball player.
Previous post The Value of Short-Term Goals in Research
Next post More than a hobby: science, music, and me.

Leave a Reply

Your email address will not be published. Required fields are marked *

Close
The newest issue of IMMpress is now available! This time, we tackled all things work culture, from universal basic income to unions and more! Check it out by clicking the link below https://t.co/dDatJRPNi8 https://t.co/2scopoDpCU
h J R
@immpressmag
VR has already changed the world in every way, from medical training to how we view entertainment. As education moves online with the pandemic, how will VR change the classroom? Click the link below to find out! 🕹 https://t.co/g1uYViavAN
h J R
@immpressmag
The newest issue of IMMpress magazine is now out! This time, we delved into the world of technology in healthcare 🔬 Check it out and let us know what you think! https://t.co/HyBn12R6Fd
h J R
@immpressmag
One of few positive outcomes from this pandemic was the advent of mRNA vaccines. And with a rise in funding for this research, scientists can continue to improve this technology. Check out this article by @pu_annie to learn everything you need to know! https://t.co/2GtcexUBvl
h J R
@immpressmag
Check out the link in our below to read the newest IMMpress blog post! Our DOI undergrads Rahman and Aly did a great job on this one 🤩 https://t.co/yeTs2q6S7x
h J R
@immpressmag

Sponsors