I an looking for a short story I read long ago, more than 30 years. It was about unusual accidents, where unusual intelligent people were killed. These accidents were the equivalent of the biocide we use when culturing bacteria in a petri dish to stop the culture spreading outside the dish. Some higher minds or beings used this to prevent us from coming too close to some higher insight or truth.
It sounds like you're talking about "Breeds there a man...?" by Isaac Asimov
"Elwood Ralson, a brilliant but psychologically disturbed physicist, becomes convinced that humanity is a kind of genetics experiment being run by an alien intelligence. His behaviour becomes more erratic and suicidal as his thoughts become more entrenched in this idea, and his health fails.
He draws an analogy between human progress and the growth of bacteria that suggests that humanity has been bred in certain strains for various traits (e.g. artistic ability) and that such breeding is what produced the Athens of Pericles and the Renaissance. He further states that the experimenters use a penicillin ring, or killing boundary, that makes humans want to kill each other should their abilities grow too great, as mental increase leads to greater "infectivity," and humanity is dangerous to the experimenters.