A recent study on human genetics on various populations across the world has shown how pathogens can shape the patterns of genetic diversity of our immune system over time. Results show that bacteria, fungi and parasites, unlike viruses, appear to have allowed the introduction of mutations in the genes of some proteins of the innate immunity system, thus enabling greater genetic variability. In some cases, these mutations may even constitute an advantage, giving the human host improved resistance to infectious diseases such as leprosy or tuberculosis.