Why do we do the things that we do? Why do we some­times choose to be lov­ing par­ents and oth­er times engage in irra­tional self-destructive behav­iors? What dri­ves us to some­times be altru­is­tic and oth­er times make deci­sions that real­ly threat­en our very sur­vival? Well, the answer lies in our brains. Our brains evolved to ensure that we repeat behav­iors that will lead to our sur­vival.