In our skin they live innumerable species of microbeYes, and in such large quantities that it is not even known for sure how many there are.
Only our navel is, for the purposes of microbial life, something like an extraterrestrial world, as evidenced by the project called Belly Button Biodiversity (BBB), that is, Navel Biodiversity Project, carried out by researchers from the State University and the Natural Sciences Museum of North Carolina.
In this project, the researchers took samples of that unfathomable part of our anatomy that is the navel, in which the microbes appear to be very comfortable. There they found, after analyzing 500 navels, a total of 2,368 different species of bacteria.
But the most surprising thing about this finding is what counts Josep Maria Mainat in your book Optimistic science:
the study specifies that 1,458 of these species of microbes were previously unknown to science and some of the bacteria detected were totally out of their usual context. A person's navel, for example, harbored a bacterium that had only been found previously in Japan, where the person had never been. Another individual had two types of bacteria called “extremophiles” in his belly button.
Extremophiles are microorganisms that live in extreme conditions, as extreme as Cherbóbil, deserts, in volcanoes, in hydrothermal sources and even in Antarctic ice.
Behind the ear, however, only an average of 19 different species of microbes.
Among the species of microbes that inhabit the skin of the right hand, only 17% coincide with those that inhabit the skin of the left hand.
All this is what we can find in our skin, but in our interior there are many more microbes. Only our digestive system welcomes more than a hundred billion microbes of at least 400 different species.
Many of them carry genes that provide us with useful features and functions for us, such as helping us assimilate nutrients, and converting the rest into excrement that we will later evacuate. We have 25,000 genes contained in our cells, but we have 20 times more non-human genes from bacteria. Are they or us? What country are we from then?