It is estimated that the worldwide average height for an adult human male is about , while the worldwide average height for adult human females is about . Shrinkage of stature may begin in middle age in some individuals, but tends to be typical in the extremely aged. Through history human populations have universally become taller, probably as a consequence of better nutrition, healthcare, and living conditions. The average mass of an adult human is for females and for males. Like many other conditions, body weight and body type is influenced by both genetic susceptibility and environment and varies greatly among individuals. (see obesity)