There’s a brief, but fascinating article on Wired News about researchers who are using functional magnetic-resonance imaging (fMRI) to see just how the decision making process plays out in the brains of humans. Of particular note are the results of experiments involving tricky moral dilemmas which show that we literally can be of two minds when making a tough decision:

Greene, together with Jonathan Cohen, professor of psychology at Princeton, is using fMRI to look at the factors that influence moral judgment.

To do so, the researchers scan the brains of volunteers while posing them fiendishly tricky dilemmas. For example, imagine you and your neighbors are hiding in a cellar from marauding enemy soldiers. Your baby starts to cry. If he continues, the soldiers will discover your hiding place and kill you all. The only way to save yourself and the others is to silence your baby—by smothering him to death. What do you do?

Clearly, you would feel intense emotions, and this shows on the brain scan. But you would also be forced to make a logical assessment of the situation, and this shows up on the brain scan too. Areas involved in abstract reasoning and those that process emotions light up.

In other words, when processing a difficult and personal moral dilemma, we really are of two minds. Greene found that if the dilemma is not so personal, the reasoning part of the brain is dominant.

When a dispute exists between two sides, say in a court of law or in a territorial land claim, there is often a mediator. So too, it seems, the brain has one too. Researchers found a region called the anterior cingulate cortex, believed to be involved in mediating conflict, was highly active in brains struggling with the crying baby scenario.

Greene and colleagues showed a neurological basis for the phrase “of two minds,” and that both compete for dominance. So does the heart rule the head? Answer: Sometimes. But the head doesn’t give in without a fight.

From there the article goes on to mention some further research which suggests that morality might be the product of more than just cultural influences:

“Everything that evolves is a modified version of something else that already evolved,” said Greene. “If you can trace the evolutionary history of the structures involved in a certain kind of thinking then perhaps you can make the case that the thinking in question is shaped by the creature’s evolutionary history.”

This kind of thinking is what led Dr. Andreas Bartels, now at the Max Planck Institute for Biological Cybernetics, Tubingen, Germany, to propose (on the basis of fMRI work) that romantic love evolved from maternal love.

Similarly, Dr. Val Curtis of the London School of Hygiene and Tropical Medicine published work earlier this year showing that our sense of disgust has evolved to protect us from disease. That sense of hygiene, said Greene, might be the basis for so-called higher senses, such as moral feelings.

Greene is currently working on this idea. “For example,” he said, “we might describe the behavior of someone who takes bribes as disgusting. I think that’s more than a simple, learned metaphor.”

Greene believes that although cultural influences on morals are strong, an important genetic element is also present. “Much of what we think of as culturally learned or individually reasoned in moral judgment,” he said, “may turn out to be driven primarily by evolutionary forces.”

Needless to say, this sort of research is going to stir up more than a few angry debates as it progresses as the implications it carries will be threatening to those who feel morality can only come from a single external source.