One might expect daring of Jack London, an author who has been gold-miner, sailor, frontiersman, adventurer; whose writing can no more be trite or commonplace than can the narrative of his own life history. But no fictionist ever dreamed of daring to attempt what Jack London has done here–to plunge into the gray mist that shrouds the beginnings of our race; to paint in vivid colors a picture of that alleged and disputed ancestor of ours; to outline his brutal life, his loves, his hates, his first efforts toward human reasoning poiver; to do all this with such wonderful vividness that the skeptic is convinced by the plain truth of it.