Are We Actually More Bacteria Than Human?

MBBS
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E.coli present in the human gut, Wikimedia Commons
E.coli present in the human gut, Wikimedia Commons1920×1615 591 KB

If we were to tally all the bacteria inside and outside the human body, from the normal flora to the invasive pathogens against the number of cells of the human body, which do you think will have the higher number?

There have been countless scientific theories to determine what composes a larger percentage of the human body between microbes and cells of the human body. An example of this is the 10:1 ratio by the microbiologist Thomas Luckey. It was a theory published in the 1972 American Journal of Clinical Nutrition that stated that bacteria from the mouth to anus outnumbered human cells by a ratio of 10:1. This theory would later be used by scientists as gospel truth for many years.

The 10:1 ratio vs modern science. Was the theory really true?

For many years, scientists went with this theory which made it seem like the human body was a bacteria super factory. That theory, like most scientific theories would later be challenged when new information was attained. In 2016, a group of scientists namely Ron Sender, Shai Fuchs and Ron Milo visited this theory and made some changes, which we still use up to today. Instead of a 10:1 ratio,they discovered that the bacteria to human ratio is actually 1.3: 1 ,a much more stable ratio. But how did they get to that figure? Unlike Luckey who believed there was an equal distribution of bacteria from the mouth to the anus, these 3 pointed out the fact that most of the bacteria in the digestive tract is actually confined to the colon. Also Luckey had miscalculated the number of human cells which he used to come up with this ratio. He estimated there are about 10 trillion cells when in reality,there are actually about 30 trillion human cells!

Cell count aside: Why our Microbial genes matter more

Even though the bacteria to human cell ratio is almost 1:1, the human genome contains about 20,000 protein coding genomes while bacteria have about 3.3 million unique genes. This is a ratio of 100:1 and is referred to as the second genome. These microbial genes are extremely essential to perform tasks the human body can not such as breaking down fiber and vitamin K synthesis

Verdict: Are we really more bacteria than human?

Physically, we will always be more human than bacteria and from a cellular point of view, we are equal. Instead of being a host to millions of bacteria crawling and feasting off of us, we are a co-existing organism sharing a mutual symbiotic relationship , depending on each other for survival.

What do you think, walking hosts or co-existing super organism? Share your thoughts!

MBH/PS

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Interesting insights from evolutionary point of view. Life originated in water and bacteria were the earliest live creatures that came into existence.

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Great post! I do agree that we are walking co -existing super organism

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This is an interesting take, loved reading it. Thankfully we are more human :sweat_smile: :sweat_smile:

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Thank you for taking your time to engage with my article​:heart:. Someday, I’d like to write an article on the effects of probiotics in vulnerable groups. It’d flip the script of my article :joy:

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Thankfully indeed :joy:. It’d be an invasion just waiting to happen

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We really do need to give those little guys a bit more credit. Outside the harmful species, they do a lot of good

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As a child i use to think bacteria means bad but as I grew up got familiar with few terms then I realised there are good as well as bad bacteria. and this post clear few more doubts It is quite interesting to know that humans are as dependent bacteria as they are on us.

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It was an interesting post.

I will go with co-existing super organism. We depend on them and they depend on us. Especially our gut bacteria do so much work for us that our own body cannot do.