What do Pythagoras, Arthur Conan Doyle, and Jack London have in common?

The Uzbekistan Boxing Federation posed an intriguing question on its official page: what connects Pythagoras, Arthur Conan Doyle, and Jack London?

The answer lies in their shared passion for boxing. While Pythagoras is renowned as the father of ancient Greek mathematics and philosophy, he was also a boxer. Arthur Conan Doyle, the creator of Sherlock Holmes, was a boxer in his youth. Jack London, the celebrated American writer, was also a boxer.