Researchers have found that a key brain system is similar in creative, mentally healthy people and people with schizophrenia, bolstering the notion that the factors that contribute to mental illness may also confer benefits.
Researchers at the Karolinska Institutet found commonalities in the brain's dopamine system between people with schizophrenia and creative, non-schizophrenic subjects. Specifically, both creative and schizophrenic people tended to have a relatively low density of dopamine receptors in the thalamus. Study author Fredrik Ullén explains that this might lead to "a lower degree of signal filtering, and thus a higher flow of information" — which would in turn give rise to both "the ability of healthy highly creative people to see numerous uncommon connections in a problem-solving situation and the bizarre associations found in the mentally ill."
Note that the creative people in the study weren't suffering from schizophrenia, and so the research doesn't back up the common misconception that people have to be mentally ill to be truly creative. What it does suggest, however, is that creativity and mental illness may have similar sources. It's certainly possible that genes that cause schizophrenia in some combinations persist because, in others, they lead to heightened creativity that might actually enhance someone's chances of survival. And creativity may be good for humanity as well as individuals. Temple Grandin argues that "autism genetics" are beneficial for the human population, though these genes are detrimental to individuals who may produce severe autism. Similarly, having a certain number of creative people around may be good for the human species as a whole. As people with "insecure attachment styles" apparently aid their social groups by spotting and reacting to threats, creative people may develop innovative ways of responding to them.