This book appears to be a biography of Alexander Selkirk, but is actually a well-researched historical novel. The author knows her sources. There are many footnotes, quotes, and factual details. You want to believe she had some way of knowing the intimate details she supplies--how people saw their situations, what their motives were, and the vivid details of their experiences that bring the story to life. After all, historical sources sometimes provide such background, and in this case we do have some sources for Selkirk's thoughts, feelings and experiences. Soon enough, however, one sees that Souhami has simply assumed the authorial omniscience of a novelist. She states as plain fact many things that she could not possibly know, including things that only Alexander Selkirk could have known and that he would not likely have revealed.
After she tells how Selkirk masturbated against palm trees while he was marooned on the island, a serious reader continues to read only to see how far she will go. At the same time it is interesting to note how she painstakingly documents some details that are not especially interesting--perhaps this is a tactic to make the book seem more like a solid historical narrative.
Her most imaginative invention is Mr. Selkirk's having sex with wild goats on the island. We do know, from his own account, that he ran down goats for sport and food, and either killed them to eat, or else notched their ears and released them. We do not know that he indulged in any other kind of sport with them. Certainly Selkirk had an abnormal capacity for violence and survived in a pirate culture that was a home for the most dysfunctional dregs of humanity. He could have been guilty of screwing goats or even kinkier things. But there is no way to know. Ms. Souhami only provides a footnote in support, implying that a present-day native of the island gave her the idea: "It is always that way with men who are alone," he tells her. Selkirk's sex with goats is not just a passing conjecture. It is a theme to which the author returns, to encapsulate Selkirk's life on the island, and to portray his attitude towards women.
I enjoyed her discussion of the myth-making that followed Selkirk's life, especially the few pages where she analyzes the public appeal of Defoe's Robinson Crusoe fantasy, which was based on Selkirk's adventures as a castaway. But she has invented another myth--one that is likely to last. In other reviews here you'll see that some readers uncritically believe her tale.
This book received the Whitbread award, in the category of biography. That was a big mistake, unless history is now to be done the way Hollywood does it. Much effort went into this book, some talent, and a commendable concern for the preservation of habitat on Selkirk's island, but no professional ethic regarding the responsibilities of historians. We'll never know whether Selkirk screwed goats, but we do know that Souhami screwed this story.