How do complex creatures consisting of millions of cells form from a single cell? Since the time of Darwin, humanity has been trying to unravel this mystery. Scientists understood that this would help answer another question - how from the very first multicellular animals came today's "infinite number of the most beautiful forms." A new field of science - evolutionary developmental biology, or evo-devo, which combined embryology, paleontology and molecular genetics, was able to explain how the future form of animals is laid out in the early stages of development. In his book, American biologist and leading expert in the field of evo-devo, Sean B. Carroll, fascinatingly and simply, using the example of a variety of representatives of the earth's fauna - from fruit flies to humans - shows how the laws of development and evolution operate, whether in a few hours, in during which a Drosophila larva develops from an egg, or hundreds of millions of years during which a new taxon of animals is formed.