A: Charles Darwin might never have published On the Origin of Species in his lifetime if it weren’t for the malarial fever of one Alfred Russel Wallace - the lesser-known co-discoverer of natural selection.

More than two decades after his voyage on the H.M.S. Beagle, Darwin still hadn’t printed his thoughts on evolution. For one thing, he was busy writing a multi-volume treatise on barnacles. The truth is, Darwin intended for his work to be published after his death. But then, in 1858, Alfred Wallace got malaria, which gave him a lot of time to just sit around, thinking, sweating, and hallucinating. Eventually, he independently thought up the same thing Darwin had.

In fact, Wallace even wrote a paper and sent it to Darwin for comment. But Darwin, fearing he wouldn’t be credited for a discovery he’d made long before, quickly put together and published a book. And while the two men agreed to share credit for natural selection, it wasn’t long before Darwin emerged as the more historically significant figure.