How does Paul say the men turn into animals during the war?

Paul first notes the change of identity that occurs at the front. The men turn into animals--and more likely the hunted, not the hunters: "Šthere is suddenly in our veins, in our hands, in our eyes a tense waiting, a watching, a heightening alertness." He later calls the soldier's impulse to seek the earth for protection an "animal instinct," and says the soldiers become "human animals" on the front.