Four classes of influences--Physical effects of environment--Stature
and environment--Effects of dominant activities--Physical effects of
climate--Pigmentation in relation to heat and light--Pigmentation
and altitude--Difficulty of generalization from geographic
distribution--Psychical effects--In Religion--In mind and character--In
language--The great man in history--Economic and social effects--Size of
the social group--Effects on movements of peoples--Segregation and
accessibility--Change of habitat.