The dogs regarded the men with their heads on one side, sniffing in the deepest possible amazement,--amazement so intense that they could not possibly feel hostility. One of them whined a little because he did not understand. _11. WARM BLOOD IS A BOND_ Peculiarly enough, it was a matter of topography. The plateau which reached above the clouds rose with a steep slope from the valley from which a hunting-spider's brood had driven the men. This was on the eastern edge of the plateau. On the west, however, the highland was subject to an indentation which almost severed it. No more than twenty miles from where Burl's group had climbed to sunshine, there was a much more gradual slope downward. There, mushroom-forests grew almost to the cloud-layer. From there, giant insects strayed up and onto the plateau itself. They could not live above the clouds, of course. There was not food enough for their insatiable hunger. Especially at night, it was too cold to allow them to stay active. But they did stray from their normal environment, and some of them did reach the sunshine, and perhaps some of them blundered back down to their mushroom-forests again. But those which did not stumble back were chilled to torpor during their first night underneath the stars. They were only partly active on the second day,--if, indeed, they were active at all. Few or none recovered from their second nights' coldness. None at all kept their full ferocity and deadliness. And this was how the dogs survived. They were certainly descended from dogs on the wrecked space-ship--the _Icarus_--whose crew had landed on this planet some forty-odd human generations since. The humans of today had no memories of the ship, and the dogs surely had no traditions. But just because those early dogs had less intelligence, they had more useful instincts. Perhaps the first generations of castaways bred dogs in their first few desperate centuries, hoping that dogs could help them survive. But no human civilization could survive in the lowlands. The humans went back to the primitive state of their race and lived as furtive vermin among monsters. Dogs could not survive there, though humans did linger on, so somehow the dogs took to the heights. Perhaps dogs survived their masters. Perhaps some were abandoned or driven away. But dogs had reached the highlands. And they did survive because giant insects blundered up after them,--and could not survive in a proper environment for dogs and men. There was even reason for the dogs remaining limited in number, and keenly intelligent. The food-supply was limited. When there were too many dogs, their attacks on stumbling insect giants were more desperate and made earlier, before the monsters' ferocity was lessened. So more dogs died. Then there was an adjustment of the number of dogs to the food-supply. There was also a selection of those too intelligent to attack rashly. Yet those who had insufficient courage would not eat.