Origins
Various theories have been proposed to explain the short stature of pygmies. Some studies suggest that the short stature of pygmies could be related to adaptation to low ultraviolet light levels in rainforests. This might mean that relatively little vitamin D can be made in human skin, thereby limiting calcium uptake from the diet for bone growth and maintenance, and leading to the evolution of the small skeletal size characteristic of pygmies.
Other explanations include lack of food in the rainforest environment, low calcium levels in the soil, the need to move through dense jungle, adaptation to heat and humidity, and most recently, as an association with rapid reproductive maturation under conditions of early mortality. (See also Aeta people#Demographics.) Other evidence points towards unusually low levels of expression of the genes encoding the growth hormone receptor and growth hormone relative to the related tribal groups, associated with low serum levels of insulin-like growth factor-1 and short stature.
Read more about this topic: Pygmy Peoples
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