AP Photo

Human evolution must be the greatest story never told. It begins in an unknowable past and continues mysteriously for the next five or six million years. Is it a thriller, an epic or a comedy of errors? There is no dust jacket, no title page, no dedication, no acknowledgements. Almost all the text is missing, apart from the occasional phrase, sentence or paragraph, seemingly torn at random from the great six-million-year narrative. If the story of humanity is a single volume, then only the last page survives.