Everyone knows the theory of natural selection (survival of the fittest), described by Charles Darwin. Not everyone knows his other theory - sexual selection, which goes into the realm of aesthetics: evolution follows the path of beauty, and this is most noticeable in birds: females choose the most beautiful or musical, and not the strongest and most durable male. The choice of the most attractive characteristic of a partner is formed generation after generation, and as a result this characteristic becomes decisive for the species. And the same aesthetic principle contributes to the evolution of all living beings, including humans. This book is for those who are interested in the nature of beauty and attractiveness, biology and ornithology in particular. It is published in Russian for the first time.