Nazi Germany's eradication of European Jews during the Holocaust, one of humanity's most despicable campaigns of violence, featured a much more ruthlessly efficient "kill rate" than previously understood — according to new research.

During the Holocaust, millions of Jews, along with members of different ethnic groups, gay men, Soviet prisoners of war, and others, were systematically murdered at concentration camps including Auschwitz, Treblinka and Belzec. They arrived at the death camps primarily by train and countless people died inside the cramped boxcars.

"Even though the Holocaust is one of the best-documented genocides in a historical sense, there is surprisingly little quantitative data available," explains biomathematician Lewi Stone from Tel Aviv University in Israel.