The other theory is Sauer’s: Man, the hunter, destroyed the larger, clumsier, and more gregarious animals largely by means of fire drives, and these fires made the grasslands.[26] Or, at least, the fire drives “broke the back” of mammalian resistance.[27] Eiseley objects on a number of grounds. It was not alone the large, clumsy, and gregarious animals that disappeared. Certain mollusks, a variety of toad, a subfamily of rabbits, the dire wolf, the saber-toothed tiger, three forms of antelope, the short-faced bear, and a small horse also disappeared. More damaging still to Sauer’s theory is the fact that a number of birds became extinct. Eiseley asks, “Why, if this method was so deadly, did the living bison and the living antelope roam the plains in countless numbers?” He points out that, while there is abundant evidence of extinct bison caught and killed in fire drives, there is no proof of mass kills of mammoth, horse, camel, and antelope.[28] He also mentions the mastodon, the giant beaver, and the sloth, which frequented eastern forests or northern bogs and died in them. “Though man was on the scene at the final perishing, his was not ... the appetite nor the capacity for such gigantic slaughter.”[29] Though Sauer believes that the numbers of hunting man in the New World were comparatively large when he killed _Bison antiquus_, most authorities disagree. Alfred S. Romer believes that if man had been numerous enough and deadly enough to play a major part in the killing, we should find more evidences of his association with the extinct mammals.[30] Romer and Edwin H. Colbert have put forward another explanation for the extinction of the mammals. They suggest that the advent of man in the New World may have upset a nicely balanced state of nature.[31] But man had been living with just such animals in the Old World for hundreds of thousands of years before they became extinct. What, then, destroyed the mammoth in Europe? The most pulling of all the fossils of extinct animals are those in the deep Alaska muck beds. Their numbers are appalling. They lie frozen in tangled masses, interspersed with uprooted trees. They seem to have been torn apart and dismembered and then consolidated under catastrophic conditions. Eden and Plainview spear points and perhaps one Clovis have been found in these chill beds. Skin, ligament, hair, flesh, can still be seen.[32] If scientists can solve this mystery before the high-pressure water stream of the miner disperses the evidence, perhaps we shall be nearer solving one of the greatest and most tantalizing problems involved in the story of early man—the date of the extinction of the great mammals.