'Your friend is very clever, though his heart is not in it. He drew away the beavers while I took the poles. The female---' He laughed. 'She was so angry. I think she would have killed me if she got the chance.' 'Killed you? A little two-foot long beaver?' 'Two feet?' he winced. 'Perhaps the beavers of your world are only that long, but I promise you, these were larger than any wolf.' She studied him, disbelieving. A bizarre thought had just occurred to her. 'Are you telling the truth?' 'Why would I lie?' She threw back the upper fold of the fur, searched among the books. She quickly found what she was looking for: PREHISTORIC EARTH, ESSAYS AND ILLUSTRATIONS. She checked the index, thumbed the yellowed and clumping pages. Her mind fell back into itself. Sure enough, sketched there in relative detail against the background of a large den, was the figure of a great prehistoric beaver, '.....eight to twelve feet in length.' Recovering herself, she moved hastily to sit beside him. 'Do they look like this?' 'Yes, more or less.' She flipped through the stiff, distending pages---Mammals of the Pleistocene. She stopped at a pair of saber-toothed cats, lurking hungrily near a tar-pit. 'What about these?' Have you seen them?' 'Yes, but it is not a good likeness.' Her mind raced so that she hardly heard him. Was it possible? Had life reverted to its primitive, violent stages before Man, evolution in reverse? Her scientific education told her no, it couldn't happen. But was anything impossible here? She doubted it. She turned the pages again, stopped at the illustration of a lesser species of cave-bear. Again she showed him the book. 'Yes, I have seen them, though they live mostly to the north and west. But it is not a good likeness.' Exasperated: 'Why, Kalus? Why isn't it a good likeness?' 'Because the bear is standing---in life a bear only stands when it is going to fight---and still he is only a head taller than the tribesman. I tell you, the bears of the north are much larger.' 'Tribesman?' In her haste she had failed to note the two fur-clad Neanderthals which stalked it, spear in hand, from behind a group of rocks. The face of the nearer was hard and set, with swept-back cheekbones and heavy, prominent brow. Eyes animal, and yet not animal. The caption said something about, EARLY MAN IS BELIEVED TO HAVE SUCCESSFULLY HUNTED..... 'No. It can't be.' Her eyes went wide. 'Your people look like this?' This time he had no reservations. 'Yes.'