Man is a social being – and this can also be seen in his brain. Researchers now know that our social life can even leave structural traces in the mind. However, the social environment seems to have different effects for men and women, as a study now suggests. Accordingly, the frequency, the intensity and also the type of social contacts in the male gender have a different effect on the volume of certain brain regions than in the female.
Typical man, typical woman: Our biology and behavior are largely determined by gender. It is becoming increasingly clear that the brains of both sexes “tick differently” in many things. For example, men seem to be more forgetful, but women feel more stress and negative feelings. Such differences are also reflected in the anatomical structures of the thinking organ – although the deviations are less pronounced than is commonly assumed. In this context, recent studies suggest, for example, that the social environment shapes male brains differently than female ones.
What role does gender play?
According to the so-called hypothesis of the social brain, the demands on life in social groups form the thinking organ visibly. For many primates – including us humans – the volume of the cerebral cortex is related to factors such as the average size of the social network. “There also seems to be a gender-specific component,” explains Hannah Kiesow from RWTH Aachen University and her colleagues. But what is it about this presumption? To find out, the researchers have now examined structural data from 10,000 adult brains using magnetic resonance imaging. She was particularly interested in the volume of 36 different brain regions – and how this correlated with the social environment of the test subjects. Specifically, they looked at the size of the household, the number of close relationships and the frequency of social contacts.
The result: As expected, there was a connection between the social life of the participants and the volume of their gray matter. This was particularly true for regions of the limbic system such as the amygdala and the ventromedial prefrontal cortex (vmPFC), but also for other brain networks, as the team reports. The limbic system plays a key role in processing emotions; the prefrontal cortex is specifically involved in emotional control, but also in decisions and the response to social stimuli. The evaluations revealed clear gender differences in these brain regions. Accordingly, the frequency, the intensity and also the nature of the social contacts seemed to have a different effect on women than on men’s brains.
Same environment, different effect
For example, in women who live in a larger household, there was a significant increase in the volume of the amygdala associated with emotions – this was not the case in men. Satisfaction with their own friendships and the frequent opportunity to entrust themselves to others also had more substantial anatomical effects in the amygdala and the vmPFC in women than in men, the researchers found. On the other hand, low social support seemed to be reflected in the male gender, especially in reward centers such as the nucleus accumbens. Another difference: In men, the number of sexual partners to date was visible in the vmPFC, while in women, satisfaction with family relationships was evident. In addition, the volume of this area of the brain responsible for emotion processing deviated more by lonely women than by socially isolated men. “This could suggest that women reflect their social situation more than men,” the researchers speculate.
All in all, it is clear that the same social environment may leave different and sometimes opposite traces in the brain in men than in women. “Everyday social interactions with family, friends and colleagues obviously influence brain circuits depending on their gender,” stated Kiesow and her colleagues. But how can this be explained? The scientists assume that the phenomenon is an expression of the different roles and behaviors that have developed in the course of evolution in the sexes.
“The social behavior of men and women was probably shaped by different needs and goals that resulted in certain neurocognitive adaptations,” they explain. For example, some of the observed relationships could be due to the fact that women typically have more close social ties and are better able to adopt mental perspectives. “Overall, our quantitative analysis supports the idea of gender-specific strategies to navigate successfully through the social world,” the team concluded.
Source: Hannah Kiesow (RWTH Aachen) et al., Science Advances, doi: 10.1126 / sciadv.aaz1170