Abstract
The human evolution was influenced by numerous variables. It is very likely that the most powerful tool of the evolution was the preasure done by pathogenic microorganisms which was responsible for very strong selection of humans.
Among the most important contributions of medicine to the health of whole human population are active imunisation protecting against the most important human pathogens both viral and bacterial origin and the development of antimicrobial drugs. Up to recently, the principal dogma of medicine was to eliminate all microbes.
This approach is wrong as the majority of microbial world is without direct threat to human. In addition, many body compartments are inhabited by very complex microbial societies designated as microbiota.
The best studied are microbiota of gut and skin microbiota. Health and microbiota is providing direct and indirect protection against pathogenic microbes.
It is also contributing to the both mucosal and systemic immunity with high impact on individual immune reactivity. Microbiota is metabolically active providing many essential substances for our body and simultaneously metabolises harm xenobiotic substances found especially in our food.