My microbes and me

During the last year I frequently stumbled over research related to the ‘microbiota’ (sometimes referred to as ‘microbiome’), which simply stands for the myriad microbes we carry around. It immediately caught my interest when I first learned more about it. I can still remember that I was totally sure that I had found a typo when I first read that we have 10-times more of those little creatures in our body than human cells!

It is absolutely correct to think of an (or better: multiple) entire ecosystems within and on top of our body. In fact, it turns out that the microbes ¹⁾When I speak of microbes I mean ‘microorganisms’ which includes bacteria, archaea, protozoa, fungi, algae (and according to many also: viruses). are so highly linked to living animals, including us humans, that they can be considered an essential part of us. In contrast to the more widespread known disease-causing pathogenic bacteria, viruses etc., most microbes in our body are non-pathogenic, some might be doing neither harm nor good, but quite a lot apparently play a crucial role for the functioning of our body. Over the last years researchers found that the microbes living in us are very intimately linked to a vast number of health-related issues. For instance, many microbes living on our skin protect themselves, and thereby us as well, against more dangerous pathogens. Another prominent example of human-microbe interplay is our gut where large numbers of microorganisms help digesting food and even produce vitamins that our own cells cannot make. Many diseases and food intolerances might ultimately be linked to our microbiota. As if this wouldn’t be strange enough there are even links between the microbes and our cognitive systems (e.g. in the cases of depressions and anxiety).

Especially when thinking of evolution the human microbiota is a highly thrilling thing to me. Microbes are everywhere and have been around for waaaaay longer than humans, so it somehow can’t surprise that they partly also evolved together. Fascinating to me is the thought that co-evolution of symbiotic microbes brings a particularly strong advantage to human beings (or any animal or larger organisms). Microbes divide fast which means that by mutations they can fairly quickly adapt to changing environments. Actually, a week means hundereds of generations for many microbes! While we humans are stuck for many years with the same genome, our microbiota has the ability to change much more rapidly and thereby to respond to changing dangers through diseases, or changing food sources (some people even call this an additional organ of us). This also means that every one of us is pretty different – gut wise…
It was indeed found that very different habits apparently result in very different gut microbe compositions ²⁾ As in the extreme case for Hadza hunter-gatherers [Schnorr-2014]. . So, whenever you are getting depressed because you feel un-original and not-special-at-all, maybe your microbes are…

Some resources:

• Elizabeth K. Costello, Christian L. Lauber, Micah Hamady, Noah Fierer, Jeffrey I. Gordon, Rob Knight, Science, Nov.5 2009, ‘Bacterial Community Variation in Human Body Habitats Across Space and Time’. Link.
• Ilseung Cho and Martin J. Blaser, Nature Reviews Genetics 2012, ‘The Human Microbiome: at the interface of health and disease’ (freely available here).
• Wikipedia entry on ‘microbiome’.
• Lora V. Hooper, Dan R. Littman, Andrew J. Macpherson, Science, June 6 2012, ‘Interactions Between the Microbiota and the Immune System’. Link.
• Schnorr et al., Nature Communications 2014, ‘Gut microbiome of the Hadza hunter-gatherers’. Link.