Brain scans of bonobos and chimps

Bonobos have more developed circuitry for key nodes within the limbic system, the so-called emotional part of the brain, including the amygdala, the hypothalamus and the anterior insula. The anterior insula and the amygdala are both implicated in human empathy. Researchers also found that the pathway connecting the amygdala and the prefrontal cortex is larger in bonobos than in chimpanzees. When the amygdala senses that an individual's actions are causing someone else distress, they may use that pathway to adjust their behavior in a pro-social direction. Chimpanzees have better developed visual system pathways, according to the analysis. Previous research has suggested that those pathways are important for tool use, a skill which chimpanzees appear better at than bonobos.