The Human Microbiome


The human skin microbiome

Ever since we humans first discovered microorganisms many centuries ago, we’ve known that the human body is host to various types of bacteria and other critters that can’t be seen with the naked eye. In the time that has passed since this first discovery, our primary focus has been on eradicating germs that make us sick. We’ve used tons of antibiotics, both in medical care and agriculture, designed various antimicrobial lotions in order to attack stubborn skin problems, and “sterilized” our homes using harsh cleaning detergents.

We’ve known for some time that not all bacteria are bad and that certain types of microorganisms positively affect our health; however, it’s only very recently that we became aware of the fact that microbes are integrated into pretty much every part of our biology.

The microbial self

Thanks to massive research projects such as The Human Microbiome project and the European Project MetaHIT (Metagenomics of the Human Intestinal Tract), in addition to thousands upon thousands of smaller studies, we now know quite a bit ab0ut the microorganisms that colonize the human body.

Each and every on of us harbors a microbiota that is made up of trillions of bacteria, fungi, and other tiny critters. Most of these bugs are found in our gastrointestinal tracts, where they maintain our gut barrier, help us break down the food we eat, and regulate our immune systems.

For the longest time, we humans devoted virtually all of our attention to the human genome. It wasn’t until very recently that we realised that the human microbiome – the collective genetic material of all the microorganisms that colonize the human body – is in some respects even more important than the 23 pairs of chromosomes that are passed down from mothers and fathers to their offspring. The genetic repertoire of the microbiome is more than 100 times greater than that of the human genome (1, 2). In other words, the superorganism that is the human body is more than 99% microbe from a genetic perspective.

Microorganisms have co-evolved with us throughout our evolution, forging symbiotic relationships. The human microbiota is considered an essential organ of the human body. In the absence of microbes, the body doesn’t function correctly. With that said, it’s important to note that the microbes that colonize our bodies aren’t us. They are as much a part of our environment as the plants and animals around us. In other words, the microbiome can be thought of both as an organ and an environmental factor. Your microbiome acts like a bridge between you and your environment, a connection that helps you adapt more rapidly to environmental changes than what would have been possible if you only relied on your human genes.

20 reasons why microbes are important

Your microbiota influences pretty much everything that goes on inside your body and greatly affects your health and well-being. The infographic below lists some of the reasons why microbes are important.


Two animated videos that explain what the human microbiome is

Video sources: and


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