I am an academic psychologist, and I have discovered a highly reliable difference between persons without and without paraphilias. (My query does not require understanding what paraphilias are.) This discovery was serendipitous, not hypothesis driven. (In case you're worried, I have followed it up carefully, with preregistered studies, and it holds.) My impression is that many useful medical findings were serendipitous and atheoretical. But I'm not a physician or medical historian, and can't come up with any I'm confident about. (Perhaps plaques in Alzheimer's, although I'm not sure how useful those have ultimately been, or how specific they are.)
Anticipating writing up the study, I'd like an example or three of situations in which a discovery was made this way–ideally the discovery would be some kind of indicator that differed between persons with and without a particular diagnosis–was not understood immediately, but ultimately proved useful.
I'm starting with "Microbiology and Immunology," because it seemed the most likely place where examples might be found.
Thanks in advance.
