Did you know the anatomy of the brain is different between altruists and psychopaths?

Altruists improve the welfare of others at the expense of their own.

Are they weirdos or superheros? What makes them do good deeds for other people they have never met?

This study measured the activity and size of different brain regions of altruistic kidney donors using magnetic resonance imaging (MRI).

They found their amygdalas are ~8% larger than normal people. This region is important for memory, decision-making and emotional reactions.

Also, altruists were better at recognising fear in others.

This is opposite to psychopaths, who have smaller amydalas and are less able to recognise or respond to fear in others.

Altruism may seem counterintuitive to evolution, since it benefits the success of others. However, it may simply be the extreme end of our innate tendency to care for our offspring, which does fit with evolution.

 

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Background

Altruists are people that improve the welfare of others at the expense of their own.

An extreme form of altruistic behaviour is donating a kidney to an unknown recipient.

Little is known about the genetic or neural basis for altruistic behaviour.

Materials and Methods

19 altruists and 20 controls were subjected to fMRI (functional magnetic resonance imaging – measures activity of different brain regions), as well as anatomical MRI to measure size. While in the machine, they were shown pictures of people with facial expressions of fear, anger, neutral and other emotions.

NOTE: Altruistic kidney donors are very rare, so finding 19 that are willing to participate in a MRI study is a good achievement.

Results

Altruists displayed increased activity of a brain region called the amygdala when viewing fearful faces, compared to controls.

In fact, their amygdalas are ~8% larger than in normal people.

Altruists were better than controls at recognising fear, possibly due to larger and/or better functioning amygdalas.

This was specific for fear, since they were no different to controls for other emotions.

Discussion

The amygdala is located near the middle of the brain and is important for memory, decision-making and emotional reactions.

This study shows it is larger and has better function in altruists.

This is opposite to psychopaths, who have smaller amydalas and are less able to recognise or respond to fear in others.

This suggests there is a continuum of amygdala size and function, with altruists and psychopaths at opposite ends.

Altruists that can easily recognise distress in others may be highly motivated to help them.

Fear is a particularly intense/urgent emotion (can involve life or death situations) and induces infantile appearances (wide eyes and high brows) that elicit caring responses.

Altruism may seem counterintuitive to evolution/natural selection, since it benefits the success/survival of others at the expense of one’s self. However, altruism may simply be the extreme end of our innate tendency to care for our own offspring, which does fit with evolution/natural selection.

Future Directions

Could it one day be possible to develop treatments that increase the size of the amygdala (e.g. cognitive therapy, stem cells) to increase altruistic behaviour in people? Perhaps even in psychopaths? Perhaps as an adjunct or alternative approach to traditional prison or death sentences?

Article

Neural and cognitive characteristics of extraordinary altruists

Marsh et al., 2013 Proc. Natl. Acad. Sci. USA 110:6925-30

Keywords

Altruism, altruistic, psychopath, brain, neuron, neural, amygdala, MRI, fMRI, imaging, emotion, survival, fear, behaviour, evolution, natural, selection

Subject

Science, Neuroscience, Psychology, SC4-14LW, ACSSU150, SC5-15LW, ACSSU185