Genetically modified chickens reveal testosterone's complex role in both male and female birds

Oct 22, 2024

Why does the rooster crow and the hen does not? This question prompted the scientist Arnold Adolph Berthold to castrate a rooster in the mid-19th century. The result of his experiment: the rooster's morning crow was over. At the time, Berthold did not know which substance in the rooster's testicles might be involved—we now know that it is the sex hormone testosterone.