As societies develop and provide better living conditions, there is a shift from low maternal and infant mortality and predominance of chronic and degenerative conditions to high maternal and infant mortality and predominance of parasitic and infectious diseases. high life expectancy and predominance of parasitic and infectious diseases to low life expectancy and predominance of chronic and degenerative conditions. low life expectancy and predominance of parasitic and infectious diseases to high life expectancy and predominance of chronic and degenerative conditions. high maternal and infant mortality and predominance of deaths due to parasitic and infectious diseases to low maternal and infant mortality and predominance of deaths due to autoimmune diseases, such as AIDS.