What is the average world height?
What is the average world height? Human height varies according to both “nature” and “nurture”. The particular human genome that an individual inherits is a large part of the first variable (nature) and a combination of health and environmental factors present before adulthood (when growth stops) are a major part of the second determinant (”nurture”). Hereditary factors include both genes and chromosomes, and are inborn. Environmental factors are events that occur before adult height is reached, such as diet, exercise, and living conditions.
When populations share genetic background and environmental factors, average height is frequently characteristic within the group. Exceptional height variation (around 20% deviation from average) within such a population is usually due to gigantism or dwarfism; which are medical conditions due to specific genes or to endocrine abnormalities. In regions of extreme poverty or prolonged warfare, environmental factors like malnutrition during childhood and/or adolescence may account for marked reductions in adult stature even without the presence of any of these medical conditions. This is one reason that immigrant populations from regions of extreme poverty to regions of plenty may show an increase in stature, despite sharing the same gene pool.
The average height for each sex within a population is significantly different, with adult males being (on average) taller than adult females. This difference may be attributed to sex chromosomal differences, XY (male) as opposed to XX (female). Women ordinarily reach their greatest height at a younger age than men. Vertical growth stops when the long bones stop lengthening, which occurs with the closure of epiphyseal plates. These plates are bone growth centers that disappear (”close”) under the hormonal surges brought about by the completion of puberty. Puberty generally occurs several years earlier in young women than in young men, and so final adult height is reached earlier in women. Adult height for one sex in a particular ethnic group follows more or less a normal distribution.
