Why does being bad feel so good? Pride, envy, greed, wrath, lust, gluttony, and sloth: It might sound like just one more episode of The Real Housewives of New Jersey, but this enduring formulation of the worst of human failures has inspired great art for thousands of years. In the 14th century Dante depicted ghoulish evildoers suffering for eternity in his masterpiece, The Divine Comedy. Medieval muralists put the fear of God into churchgoers with lurid scenarios of demons and devils. More recently George Balanchine choreographed their dance.
Today these transgressions are inspiring great science, too. New research is explaining where these behaviors come from and helping us understand why we continue to engage in them—and often celebrate them—even as we declare them to be evil. Techniques such as functional magnetic resonance imaging (fMRI), which highlights metabolically active areas of the brain, now allow neuroscientists to probe the biology behind bad intentions.
The most enjoyable sins engage the brain’s reward circuitry, including evolutionarily ancient regions such as the nucleus accumbens and hypothalamus; located deep in the brain, they provide us such fundamental feelings as pain, pleasure, reward, and punishment. More disagreeable forms of sin such as wrath and envy enlist the dorsal anterior cingulate cortex (dACC). This area, buried in the front of the brain, is often called the brain’s “conflict detector,” coming online when you are confronted with contradictory information, or even simply when you feel pain. The more social sins (pride, envy, lust, wrath) recruit the medial prefrontal cortex (mPFC), brain terrain just behind the forehead, which helps shape the awareness of self.
No understanding of temptation is complete without considering restraint, and neuroscience has begun to illuminate this process as well. As we struggle to resist, inhibitory cognitive control networks involving the front of the brain activate to squelch the impulse by tempering its appeal. Meanwhile, research suggests that regions such as the caudate—partly responsible for body movement and coordination—suppress the physical impulse. It seems to be the same whether you feel a spark of lechery, a surge of jealousy, or the sudden desire to pop somebody in the mouth: The two sides battle it out, the devilish reward system versus the angelic brain regions that hold us in check.
It might be too strong to claim that evolution has wired us for sin, but excessive indulgence in lust or greed could certainly put you ahead of your competitors. “Many of these sins you could think of as virtues taken to the extreme,” says Adam Safron, a research consultant at Northwestern University whose neuroimaging studies focus on sexual behavior. “From the perspective of natural selection, you want the organism to eat, to procreate, so you make them rewarding. But there’s a potential for that process to go beyond the bounds.”