I was directed to post here by the mods on r/history. This may be the wrong place to ask this and if inappropriate, the mods will of course remove it. Also I don't mean any offense to anyone with this question.
Regarding Auschwitz, I hear that sometimes people were gassed in huge rooms by the hundreds. Sometimes within a day or two of their arrival. Other cases are of people surviving 2-3 or even more years and eventually surviving. Do we have any information on why some people were kept alive for a longer time and some people were gassed immediately? Who chose who lived and died?
Upon the implementation of the Final Solution, inmates arriving at Auschwitz were subjected to selection by SS officers. This was conducted on the train platforms. Those deemed fit to work as slave labour were directed to the officer’s right and admitted to the camp. Those deemed unfit included all children, all the elderly, anyone physically unfit as well as adult women with young children. These were directed to the officer’s left and sent straight to the gas chambers.
Life for those who survived the selection process was extremely harsh. Meagre rations, disease, overwork, summary beatings and suicide claimed the lives of many of Auschwitz’s inmates and only a relatively small number survived to see liberation in 1945.