What learning is Gabriel Okara referring to in his poem Once Upon a Time And I have learned too To laugh with only my teeth and shake hands without heart also say Goodbye?

In his poem "Once Upon a Time," Gabriel Okara is referring to the learning of how to conform to societal expectations and norms, even when they go against one's true feelings or beliefs. He speaks of learning to "laugh with only [his] teeth" and "shake hands without heart," which suggests that he has learned to put on a façade and pretend to be something he is not in order to fit in. He also mentions learning to say "Goodbye" without feeling anything, which could be interpreted as learning to emotionally detach oneself from others in order to avoid getting hurt. Overall, Okara's poem suggests that he has learned the art of social conformity, but at the cost of his own authenticity and emotional well-being.