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Altruism: Nature or nurture?

A recent study found those who were wiling to give someone a kidney had a larger right amygdala, a small organ in the brain that helps us perceive emotions in others. How does this play into other theories of what's behind an altruistic person?

Why are some children kind to others and other children just plain mean? The root cause of altruism, and conversely selfishness or even evil, has been a debate since the beginning of human self-consciousness. The second story in the Bible is about Cain murdering his younger brother Abel out of jealousy and anger. As brain science gets more objective and there's less guessing, we are getting a glimpse of what causes behavior.

Abigail Marsh, PhD, and colleagues at Georgetown University knew that the right sided amygdala in the brain of psychopaths was in general smaller than average so they looked at the right sided amygdalas of extraordinarily giving people in a recently published study.

The amygdala is a small, paired (one on each side of the body) organ in the brain that helps us perceive emotions in others.  Psychopaths are not just ignoring the feelings of others, they actually do not understand that people have those feelings. Knowing this, Marsh choose to study the people who were the most giving to others, organ donors, and see what their amygdalas were like.

Her group found a large group of people who had voluntarily given up a kidney to save another person life.  The scientists imaged their brains and compared the right and left amygdala to the average. No pattern to the left amygdala, but they found the right amygdala averaged 8 percent larger than average, while psychopaths averaged about 8 percent less than average.

So we now have another theory about why people will sacrifice themselves for others. Followers of Darwin say that the more closely someone is related to you, the more likely you are to sacrifice yourself for his or her benefit. This is because you are not having children, but you are saving allied genetic material. Probably true from many experiments, but not a complete answer. Other sociologists say altruism is needed to preserve the future of the group, also true, but only a part of the answer.  We now add right amygdala size and it seems that those who understand other people's feelings best are more likely to sacrifice themselves. Again true, but insufficient.

The answer to the eternal question "is it Nature or Nurture" is almost always "both." From diverse fields of research, it is clear that there are many social factors involved in altruism.  People are more likely to be altruistic if they grow up in households with deep religious feelings, in households that are closely involved with their neighbors, or in households where people routinely volunteer in civic endeavors.

Now that we know that there are physical factors involved with self-sacrifice: maybe having a large right amygdala can overcome an environment that is not giving and maybe having a small one can kill altruism in a child even if their parents are practically saints.

My wife and I are both natural volunteers, but making meals for the homeless or volunteering for community groups and giving up your limited free time is not the level of altruism of giving up a kidney or jumping on a bomb to save your fellow soldiers.  We are very happy that our four children also are volunteers and we hope that such behavior was at least partially learned in our home.  But true altruism clearly has another inborn component.

Parents are always wondering why their child is not behaving well. In this situation, I am often wondering how their children can be behaving so beautifully when their parents are not following any of our suggested rules for them.  Both these paradoxical situations have to do with the fact that behavior is a combination of nature and nurture. We may think we have total control over our children, but we are wrong.  We can only do our best.

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