What is the theme in A Primate's Memoir by Robert M. Sapolsky?

The meating between mind and heart is the major theme in the book. Robert Sapolsky introduces himself as a young and aspiring scientist. However, the reader may have, upon opening the book, expected a story primarily about a scientist and his relation to his science. However, A Primate's Memoir is not primarily a work about science or about the scientific work completed by a particular researcher and it is not about a particular individual's struggles with science either. The life of 'the mind' is in fact not a particularly prominent part of the book. Instead, it is a work primarily of heart and humanity.