People who are left-handed are more likely to be atheists, according to a study which suggests that religious people have fewer genetic mutations.
Researchers at Oulu University in Finland, said that in pre-industrial times religiosity was passed on like other genetic attributes because it was associated with greater stability, mental health and better social behaviour.
Lack of belief in god is connected to genetic mutations which cause attributes such as left-handedness or autism, according to the study published in the journal Evolutionary Psychological Science.
Modern religious people were likely to be descended from those who were highly religious in pre-industrial times, researchers said.
"By contrast, atheists and believers in the paranormal would, disproportionately, never have reached adulthood or never have been born, because these beliefs, though very different, are partly an expression of the breakdown of selection and thus of rising mutational load," they said.
Researchers identified people who were either left handed or had autism or schizophrenia and examining whether they were more or less likely to be religious, The Telegraph reported.
It found that there was a "weak but significant" association between left-handedness and being non-religious, and a stronger one between autism and being non-religious.
Studies have previously established that around 40 per cent of someones religiousness is determined genetically.
