Abstract
A neurophysiological cause for the cruelty expressed by the Nazis during the Holocaust is suggested, as well as certain tests for the adult population intended to reveal such a social danger. The cause is seen as an unbalance in the development of the brain's hemispheres. It is assumed that this unbalance can occur in a nation which is under an extremely intensive stress of intellectual (cultural) development, which might be, for example, because of technological competition between nations/countries. Cruelness is purposed to prevent (further) development of the right hemisphere.