The Human Superorganism Until recently, researchers had not yet discovered all the things that creep and crawl inside and over the surface of our bodies. Since many microorganisms could not be cultivated in a Petri dish, they remained unknown. But now these colonists can be identified based on minute samples of genetic material. Thanks to advanced methods, microbiologists can use even the tiniest traces of DNA -- such as in a fleck of skin or on dental plaque -- to identify different species of bacteria.
In Europe, China and the United States, researchers have catalogued the colonists of hundreds of people. According to these findings, every human being lives in a microbial bubble. In addition to viruses, protozoa and fungi, more than 100 trillion bacteria, belonging to over 1,000 species, colonize the surface and deep layers of skin on our bodies (see graphic). They possess more than 100 times as many genes as their large host.
From a microbiologist's point of view, Homo sapiens is not an individual but, rather, a superorganism that only thrives because the members of this community have been living together since primeval times. Intestinal bacteria contribute 36 percent of the small molecules that are present in human blood. These tiny organisms process vegetable sugar molecules and thus meet 10 percent of the caloric intake requirements of the human ecosystem. The aggregate of all inhabitants of the body, the so-called human microbiota, constitutes an independent organ. Weighing in at 2 kilograms (4.4 pounds), it's heavier than the brain and has a biochemical activity that is comparable to the liver's.
This superorganism has evolved over millions of years -- and doesn't cope well with some of the innovations of the modern world. Antibiotics, for instance, may destroy dangerous bacteria, but beneficial ones also unfortunately suffer. Only two treatment cycles of the synthetic antibiotic ciprofloxacin are enough to deal a painful blow to the microbiota. Although the intestinal bacteria eventually grow back, it's now known that they don't regain their original degree of diversity.
Nevertheless, antibiotics continue to be carelessly prescribed to patients. In the US, the average child will have taken antibiotics between 10 and 20 times by the time he or she reaches the age of 18. This has prompted New York-based researcher Martin Blaser to refer to the "disappearing human microbiota." In medical journals, alarmed physicians have warned that the body's naturally healthy symbiosis is, in many cases, transforming into a debilitating microbial imbalance known as dysbiosis. Dangerous Microbial Imbalances
People affected by such microbial imbalances are often prone to allergic disorders, chronic inflammation of the small intestine, intestinal cancer, Type 2 diabetes and pathological obesity. Recent studies indicate that an impoverished flora could even be a contributing factor for Alzheimer's, Parkinson's, multiple sclerosis and autism.
The sophisticated, yet delicate nature of microbial life becomes apparent right at birth. When a newborn slides through the birth canal, it is automatically inoculated with lactobacilli from the mother's vagina -- precisely the bacteria that the infant requires to digest the mother's milk.
But during a C-section, this natural colonization can no longer take place. The baby is colonized at random, often by airborne bacteria from surfaces within the delivery room.