British psychiatristTim Crow, who worked on the evolution of human psychiatric disease such as schizophrenia, proposed the gene is a major contributor to lateralisation, which he believed underlies human cognitive abilities. Humans are a strong outlier in brain lateralisation among primates, which among other effects gives rise to our relatively unique handedness trait.[6] Further, there is a substantial bias towards right-handedness in all modern humans as compared to chimpanzees: 90% of humans will use their right hands for minor motor tasks, whereas chimpanzees display no preference.[3] Crow suggested this precludes a random or cultural origin for right-preference, adding that true ambidexterity is associated with developmental delay and psychosis.[7]
