Study links altruism to specific brain site

What accounts for differences in the level of altruism we display? Why are some people generous, while others are not? 

Some of the answer is surely cultural, as there are marked differences between cultures in the frequency and forms of altruistic behaviour. But a new study, published in the July 12th issue of Neuron and reported online last week, shows that there is a measurable physical component to altruism. People who are more altruistic have more grey matter in a particular part of their brains, and that region is more active in them than in people who are less altruistic.

The Neuron study shows for the first time that there is a connection between altruism and the anatomy and activity of the brain.

While study volunteers played a game in which they had to decide how much to share a sum of money with an anonymous person, brain scans measured the activity in the temperoparietal junction (TPJ), the spot in the brain where the temporal and parietal lobes intersect. Previous studies had shown that this region is particularly associated with a person’s ability to recognize the point of view of another person. Researchers reasoned that the same brain area might be associated with altruism, which is related to this kind of empathy.

The test results showed that those subjects who were most altruistic (shared the most money) had higher activity in the TPJ, suggesting that their brains were working to overcome the natural instinct to hoard and protect resources.

More than this, the study also showed that the most altruistic participants had a larger volume of gray matter in the TPJ.

“The structure of the TPJ strongly predicts an individual’s setpoint for altruistic behavior, while activity in this brain region predicts an individual’s acceptable cost for altruistic actions,” says study author Yosuke Morishima of the University of Zurich. “We have elucidated the relationship between the hardware and software of human altruistic behavior.”

As always, there are several ways to react to studies like this.

Those people who cling to the romantic notion of a brain-independent, free-floating personality will find the study soulless and dehumanizing. Those who are wary of anything that smacks of reductionism will find it typically shortsighted and narrow. And those who distrust the methodology of the study will dismiss the brain scan evidence as just another case where ambiguous neuronal noise is irresponsibly over-interpreted.

As anyone who reads this page with any frequency knows, I don’t have much patience for the first objection. And while I accept the limitations of brain scans, I am not particularly threatened by the spectre of reductionism.

My sanguine acceptance of descriptive brain research is a product of the realization that (1) whatever goes on in what we experience as “mind” is the result of specific physical processes in the brain and (2) describing the mechanisms of mind is not the same thing as claiming that mind is its mechanisms.

This bears restating.

Without the brain, there is no mind. Simple, straightforward, uncontroversial to anyone who’s gotten beyond the ghost in the machine. The mind is not the brain; but the mind is not, without the brain. A clock is not 3PM, but without the clock you can’t know that it’s 3PM, nor even have a useful concept of “3PM.”

If the mind is a dynamic expression of the brain’s perception and organization of somatic and sensory inputs — a simple but likely enough definition — then working out how the brain works can tell us how mind works, but not what mind is. That’s because mind is, indeed, a dynamic expression. It’s something we experience. Describing the workings that produce our experience is not to reduce the experience to its originating parts any more than our experience of a piece of music can be reduced to an understanding of the mechanisms of the instruments that produce it.

So as always I find this kind of study very interesting — and not at all impious or debasing.

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