What does the death of Meir and his father reveal about human nature?

Early in the novel Meir Katz is described as a giant of a man, a "colossus." Though the reference to him is brief, he is symbolic of the inability of even the physically strongest of men to escape the torture inflicted by the Nazis upon the Jews. Later we are told that in Buna he had been a gardener and brought vegetables to Eliezer and his father and that because he was stronger than others, "detention had been easier upon him." But even Meir, "the sturdiest of us all," gives up the will to live, in spite of Mr. Wiesel's urging him that he must resist, must not lose faith in himself. Meir's own son had been taken from him at the initial "selection," but it is only now, during the transport of the prisoners at the approach of the Red Army, that Meir weeps openly, and then expires on the transport train.
Elie's own father contracts dysentery and yet lingers until the morning after an SS officer has savagely struck him in response to his plea for water. That he has continued in spite of the illness, malnutrition, and beatings is a sign that he is living primarily because of his son. But his death, and the death of Meir not long before, both are indications that although it is human nature to try to survive in spite of every outrage and horror that is perpetrated upon one and one's family, there is a limit to anyone's endurance. In the camps it is actually a miracle that anyone has had the ability to survive. Ironically when these two men die, it is a testament to their own courage that they have lived as long as they have and not given up amid all the terror inflicted upon them.