New research shows that people who behave more altruistically have more gray matter at the junction between the parietal and temporal lobes.
This shows, for the first time, a connection between brain anatomy, brain activity and altruistic behavior, say the researchers from the University of Zurich.
Headed by Ernst Fehr, the team of researchers began their investigation on whether differences in altruistic behavior have neurobiological causes by asking volunteers to divide money between themselves and an anonymous other person.
The participants always had the option of sacrificing a certain portion of the money for the benefit of the other person, the researchers said, noting such a sacrifice can be deemed altruistic because it helps someone else at one’s own expense.
The researchers found that some participants were almost never willing to sacrifice money to benefit others, while others behaved very altruistically.
The aim of the study, however, was to find out why there are such differences. Previous studies had shown that a certain region of the brain — the place where the parietal and temporal lobes meet — is linked to the ability to put oneself in someone else’s shoes in order to understand their thoughts and feelings.
Consequently, the researchers suspected that individual differences in this part of the brain might be linked to differences in altruistic behavior.
“People who behaved more altruistically also had a higher proportion of gray matter at the junction between the parietal and temporal lobes,” noted researcher Yosuke Morishima.
The study participants also displayed marked differences in brain activity while they were deciding how to split up the money. In the case of selfish people, the small brain region behind the ear is already active when the cost of altruistic behavior is very low, the researchers report.
In altruistic people, however, this brain region only becomes more active when the cost is very high. The brain region is activated especially strongly when people reach the limits of their willingness to behave altruistically.
The reason, the researchers suspect, is that this is when there is the greatest need to overcome man’s natural self-centeredness by activating this brain region.
“These are exciting results for us,” said Fehr. “However, one should not jump to the conclusion that altruistic behavior is determined by biological factors alone.”
He noted that the volume of gray matter is also influenced by social processes. This raises the “fascinating” question as to whether it is possible to promote the development of brain regions that are important for altruistic behavior through training or social norms, he said.
Source: University of Zurich