The first thing to keep in mind is that this book is more of a history of art and culture than a proper history book. This is very important to highlight because, as Colliss Harvey's background isn't that of a historian, this book will contain several notable blunders and errors that readers with a background in history will surely notice.
So, take this as a ride through cultural trends about red hair throughout the ages, and nothing else. It doesn't pretend to be anything else, in any case. As an exploration of the various myths, legends, superstitions, and stereotypes that have been created around redheads, it's a fun read; the author obviously has a solid footing in artistic matters from creation of artworks to trends and fashions, so that's going to be the most enlightening parts. The earlier parts, purely evolutionary and historical, not so much.
If you ever wondered why there is so much folklore about red hair as well as meme-like tropes such as them not having a soul, this book is going to answer your questions. All of them, indeed, but not in depth. As I said, it's merely a cultural overview and it's not a long book. But you'll sure get your most pressing questions answered. In my case, most of what I read here was in agreement with what I had already surmissed from bits and pieces elsewhere or guessed on my own, but there was still enough knowledge that kept me reading with interest in spite of the occasional blooper. For example, I didn't know why exactly red hair was the hair of treason (Judas, if you're curious) or where the soulless redhead joke came from (you gotta read the book to find out, I ain't spoilin' it!), and more intriguingly, I wasn't aware that the negative and positive stereotypes and beliefs about redheads were actually gendered! Meaning, there's no uniformity of them applied to male redheads and female redheads.
That was quite intriguing, and perhaps the greatest contribution this book made to my arsenal of general knowledge for when I want to win a trivia game or impress my fiancé. For that alone, the book gets a firm thumbs up from me.
I might have to get a copy for the proud redheads in my tribe...