What is the author's tone in the book, A History of the World in Six Glasses?

A History of the World in Six Glasses by Tom Standage is a book about six of the world’s favorite and most important drinks, drinks that seemed to emerge at pivotal times in the history of man. Although the title could hint that the book is a light, fun look at history, it is actually a serious work that is supported by voluminous references, research and resources.