The human mind spends much of its time directing thoughts and actions toward choosing a suitable mate and creating offspring. Passing genes on to the next generation – early and often – is a guiding instinct in the animal world. From an evolutionary point of view, reproduction is the most important step for the development of the species and is primarily based on sexual selection – the choice of a partner with the most suitable physical and genetic traits for the creation of a healthy offspring. These traits give the future generation the best chance of survival, and most are visible to the naked eye, but have a stronger meaning in the subconscious. Beauty, for example, is one of the clearest signs of physical health and fertility. But beauty itself is not only expressed in large muscles in men and large breasts in women – bilateral (two-sided) symmetry is much more important. The lack of symmetrical balance in the proportions of human features is interpreted as a sign of a stress factor that the organism has not coped with and is perceived as repulsive. Another attractive characteristic is the relationship between the size of the hips and the pelvis: when the circumference of the hips is narrower than the pelvis and men and women are automatically attracted, this is a signal of good levels of sex hormones and physical endurance. NEWS_MORE_BOX Some factors are invisible and hard to detect, like pheromones. They are hormone-like compounds that send chemical signals, but not inside the body, but outside it. According to several scientific studies, women can pick up strong signals from men’s body odor, such as whether they are genetically compatible – the more similar they are genetically, the stronger the attraction. The only difference in the rule is that they prefer – completely unconsciously – partners that detect different immune system proteins known as MHC (major histocompatibility complex). The combination of genes encoding different MHC properties gives the next generation a stronger immune system, which automatically makes it attractive to pick up a foreign and different MHC signal. For additional information, we attach the following video