Only on the "CBS This Morning" podcast, author Thomas Page McBee discusses the nuances of gender with CBS News' Anne-Marie Green. As a trans man, McBee shares his experience of how a near death encounter when he was a female and an act of violence after he transitioned, lead him to the question of "Why do men fight?" He attempts to answer that question in his book, "Amateur: A True Story About What Makes A Man." He also discusses how interactions with the opposite sex changed after his transition at 30 years old and the gender expectation society has set.