EN
Reproduction is one of the basic biological functions in animals and humans. Due to the high biological relevance of reproduction and energy investment in their rearing offspring need to be of the best genetic quality and fitness to ensure preservation of the species. Both males and females employ mating strategies that would promote reproduction success and survival of their offspring. Choosing a high-quality mating partner is considered to be the main strategy in the reproduction process. One of the factors influencing the partner’s attractiveness is Major Histocompatibility Complex class I (MHC I). The influence of MHC I on mate choice is well established in animals, whereas it is still questioned in humans, where the social status of a partner may strongly influence the mate choice. In this review the role of the MHC I on mate choice in animals and humans is discussed. The studies published so far show that all investigated mammalian species can detect fractions of the MHC I molecules in urine and other body fluids. The response to the signal carried by MHC I is context-dependent and varies not only between species, but also between genders and may be modulated by various socioecological factors in every phase of the reproduction process, until zygote formation. These results suggest that MHC plays an important role in the choice of a reproductive partner in all mammal species, including humans.