Until now scientists have understood that the human brain shows different functions depending on the sex of individuals in a hormonal-based sex ratio system. But the mechanism underlying how the brain executes this sex-dependent function was unknown.

An international study led by Prof. Luke ONeill is the first validation study to show the genetic basis of this missing role.

For the first time we have been able to confirm human brain homogenisation in this software system by revealing an evolutionary mechanism guiding homogenisation in the cognitive system said the studys lead author Dr. Jennifer Li from the Faculty of Biology and Cognitive Sciences University of Sydney Australia.

The study published in Science Advances was funded by the Australian Research Council.

It analysed gene expression changes in the core networks of the brain as well as non-core networks and cortical regions and the brainstem using individual patients brain MRI data.

In men and women brain networks that process visual attention such as the visual grid are overactive in males but suppressed in females. This is an adaptation that enabled our ancestors to optimally hunt during the day and sleep at night in highly exposed populations.

In the study 10 female participants guessed the visual attention of a male fager compared to 10 male respondents with the same right hand movements.

The male patients were put on a similar task in which they only had to guess the womans hand movements but did not have to move her hands but the female patients had to move their hands while being asked about her hand movements while they guessed the mans hand movement.

The scientists found a significant difference in the prefrontal cortex the brains regions responsible for cognitive control and decision-making.

It was found that the female patients were more sensitive to a tendency to represent visual attention implying that the visual attention of females is constricted to less attention while the males do not show this constricted behaviour.