This episode features Tim Urban, author of popular longform illustrated blog Wait But Why. Julia and Tim explore one of their common interests: the tension between the rational and irrational aspects of human nature. Is there any value in the "irrational" parts of us (such as Tim's colorfully named "instant gratification monkey" and "social approval mammoth")? And can recognizing that tension help us live better -- or are we stuck struggling between our animal and rational selves?