Researchers studied how fungi that normally infect cats and dogs are adapting to infect humans. By comparing the genes of zoophilic (animal-loving) and anthropophilic (human-loving) Microsporum species, they found that human-adapted strains have developed specific proteins that help them survive in the acidic environment of human skin. These fungi have evolved special enzymes for breaking down keratin and tolerating the lipid-rich, acidic conditions of human skin better than their animal-loving relatives.