Is it always harder to teach an old dog new tricks? Why is an older person slower to learn a new language but able to learn new faces easily? Why does Arnold Schwartzenegger have an accent but Mila Kunis doesn’t, even though neither spoke English as a child? Why is there a correlation between how tall a person is and how much salary they're likely to earn? What would it mean to say that you are born as many people but die as a single one? This week's episode dives into surprises about brain plasticity and why your flexibility changes throughout your lifetime.