A recent magnetic resonance imaging research study has shown that it is possible to distinguish males and females with an accuracy of 93%, just using brain images. Duarte-Caravajalino and colleagues from UCLA used diffusion tensor imaging in a study reported in the journal Neuroimage. Diffusion tensor imaging is a new process by which connections between different parts of the brain (made by the white matter fibres, that are like tiny wires) can be imaged. They found that female brain connections were more symmetrical and had more connections from the left side of the brain to the right; male brains tended to be asymmetrical and had more connections between areas on one side of the brain. The researchers found no interactions with age between the ages of 7 to 22 (the ages of the persons studied) showing that these changes are not due to different cultural experiences.
Men are known to be better at visual orientation than women and this sex difference has been found in infants as young as three months. Men are better at rotating an object in their mind. Women have better verbal fluency and a better memory for objects. They remember better where things have been put. Men are better at navigating by cardinal direction (for example going northwards) whereas women tend to navigate using landmarks.
Personality differences between the sexes have been thought to be small but Del Giudice from the University of Turin, reporting in the journal PLOS One, found extremely large differences between men and women in a large US sample of over 10,000 persons. The authors state that personality differences between the sexes have been consistently underestimated in the past because of inadequate methodology.
One commonly quoted theory is that men and women start off with a single type of “intersex” brain and that individuals’ personalities are made up of a mosaic of “masculinizing” or “feminizing” influences. Larry Cahill, Professor of Neurobiology and Behaviour at the University of California, Irvine wrote in Cerebrum in April, that there is no evidence to support this. There is a limit to how much the brain can be changed by training, as for example a left-handed person who is forced to use their right hand will never be as good with their trained right hand. People’s brains are not just a “blank slate” that is mouldable, and we are just beginning to discover how large are the inherent differences in structure and function between the sexes.
New interesting research is also beginning to emerge on differences in moral judgments between the sexes. Fumagalli and colleagues from the University of Milan studied how men and women responded to several personal moral dilemmas. For example, they were told to imagine they were a doctor and they had five dying patients who could only be saved by transplanting five organs from a young man – but against his will, and that this would kill him. They had to give a quick yes/no answer. The researchers found that men were more likely to make “utilitarian” judgments than women and would be more likely to choose to transplant in this situation.
In a separate internet study, Bouhnik from Israel, writing in the Journal of the Association for Information Science and Technology recently found girls were more likely to make a “humane” judgment and tended towards judgments that reflected adherence to peer-group conventions than boys.
These findings have implications for the new proposed legislation on gender in Malta. What is being proposed is that individuals who feel that they have the wrong gender can freely and easily choose to change their gender. “Gender identity” is defined in the Act as “each person’s internal and individual experience of gender, which may or may not correspond with the sex assigned at birth” This research is telling us that we have a hard-wired brain structure which underlies the sex-specific way we act. We can change the external way we act and look into that of the opposite sex, but it is likely that a lot of the actions and decisions of trans-sexual persons will be strongly influenced by the brain structure of their original sex. The definition of “gender identity” in the proposed Act appears to be superficial and seriously lacking. Something that is so deeply written in our brain should not be changeable by a simple application to the Director of the Public Registry. An unhurried period of consultation with experts, and assessments to ensure the right decision is being made and that the individual knows all the risks and implications should be mandatory.
Dr Patrick Pullicino
