Linux Versus E. coli

In 1991, a 21-year-old Finnish computer science student named Linus Torvald got annoyed. He had bought a personal computer to use at home, but he couldn't find an operating system for it that was as robust as Unix, the system he used on the computers at the University of Helsinki. So he wrote one. He posted it online, free for anyone to download. But he required that anyone who figured out a way to make it better would have share the improvement with everyone else who used the system...