In 1958, Demitri Belyaev and Lyudmila Trut started an experiment on domestication. From a large group of foxes, they selected the ones that reacted to humans with more curiosity and less aggression. In each generation, they selected only the friendliest pups to become parents — hoping to recreate the process that originally led to domestication thousands of years ago. The experiment made stunning progress. Even though the foxes were chosen only for their friendliness, they soon started to get many of the physical traits that we associate with domesticated animals — like spots, flop ...