Through the Wormhole, Season 6 (2015)

Morgan Freeman:
  It may not be as hard as you think for a bigot to have a change of heart.  If any of us has a positive experience with someone from a different racial group, biology has the power to make us feel empathy for a stranger from that group.  In facts, Peggy believes that empathy is a primal instinct for all mammals.

Peggy Mason:
  What rats tell us is that we have a mammalian inheritance which makes us want to help another in distress.  But the amazing thing we learn from the rats is that what the rats need to do is to have an experience with a different type of rat, and then that rat can be part of their in-group, too.  And that's really—that's really an amazing and hopeful message, I think.