Some people are generous--others, not so much. Why is that?

A new study from Switzerland suggests that the answer to that question may be a matter of neuroanatomy, with the brains of altruistic types having more "gray matter" in a region of the brain known as the temporoparietal junction.

It's the first study to show a clear link between brain structure and altruism, according to a written statement released by the University of Zurich.

For the study, researchers led by Dr. Ernst Fehr--director of the university's economics department--asked 30 healthy adults to divide money between themselves and an anonymous person. What did the researchers find? While some of the study participants behaved altruistically, others were unwilling to sacrifice any money to the other person.

MRI scans showed key differences between the brains of participants who were altruistic and those who were selfish.

"People who behaved more altruistically also had a higher proportion of gray matter at the junction between the parietal and temporal lobes," researcher Dr. Yosuke Morishima, a postdoctoral researcher in the department, said in the statement.

The temporoparietal junction is known to be associated with decision-making. Disruptions of the region can affect the ability to make moral decisions.

Does the provocative finding suggest that altruism or selfishness is hard-wired into the brain? Not necessarily.

"One should not jump to the conclusion that altruistic behavior is determined by biological factors alone," Fehr said. Social "processes" also play a role, he said, adding that the findings raise the question of whether training people to be altruistic could encourage the growth of certain regions of the brain.

What sorts of social processes does Ernst have in mind? "This could be everything similar to what parents do repeatedly when they point out to their children that they should share resources with other kids or that they should take other kids interests into account when making decisions," he said in an email to The Huffington Post.

The study was published in the July 12 issue of the journal Neuron.

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