Human Brains Have Evolved Unique ‘Feel-Good’ Circuits

A chimpanzee skull, at left, and a human skull. Scientists are probing why our brains evolved so differently despite many similarities.

A comparison of brain tissue from monkeys, chimps and humans suggests that our brains produce the chemical messenger dopamine, which plays a major role in pleasure and rewards, far differently.

(Image credit: D. Roberts/Getty Images/Science Photo Libra)