Biological Basis of Morality
published yesterday by researchers from the University of Iowa and Harvard University (including Dr. Antonio Damasio, author of "The Feeling of What Happens" and "Decartes' Error") have shown that a particular region of the brain, the ventromedial prefrontal cortex, is responsible for mediating our moral judgments.
Specifically, for transforming what would be a simple utilitarian ethical calculus into something more akin to the Moral Razor. In the study, people with injuries to this part of their brain were more willing to sacrifice the lives of their fellows in order to save a larger number, even if it meant flat-out murder.
The ventromedial prefrontal cortex is a region which is thought to allow for social emotions, like compassion. These emotions seem to be essential for correct moral decisions in high-stakes situations; they seem to provide the moral foundation for higher-level ethical analysis which preserve moral symmetry through subconscious feelings.
According to Dr. Damasio:
This area, when it’s working, will give rise to social emotions that we can feel, like embarrassment, guilt and compassion, that are critical to guiding our social behavior. A nice way to think about it is that we have this emotional system built in, and over the years culture has worked on it to make it even better.