Why the Pygmies are so short
The Pygmies are an African tribe that are often mistakenly regarded as "little people", even though the Pygmies indeed rarely exceed 1.5 meters in height, but the reason is not their actual height but the special stretched stance that they learn to hold.
When a child is born, he's already used to seeing teens and adults standing in this position a lot, so he tries to repeat that without even being forced.
It's considered important for a tribal person to be flexible, much like in our society it's considered important to be educated. We see educated people as if they're better and more improved human beings, even though almost nobody realizes that education is an extremely unnatural thing and children are basically tortured to learn and remember random things that they will never use. This modern form of child abuse that is education is seen as something completely normal.
Anyway, children get accustomed to holding the stance since the earliest age to develop a special curve of the spine which is considered to be good by the tribe's standards, as they specificially like the ribcage to be well defined, unlike our society that almost legally puts obese people's standards above everybody else's.
Holding this stance helps the children to naturally learn a great number of various other flexible contortions of the body, which they then show at the many festivities that this very peaceful tribe holds monthly. Mostly to honor all kinds of plants and vegetables, as well as the powers of nature.
The Pygmies have learned many contorted positions from the sophisticatedly intertwined trees that grow everywhere in their jungle. The predators such as snakes and panthers normally don't touch the members of this tribe as this people is perfectly capable of talking the body language of these animals.
By the teenage years they are usually capable of folding the spine completely in half and laying flat on their lower back simply by relaxing the torso and without any kind of external pressure.
That's why all teenagers of the tribe have this stage in their life where they have to dance and perform for the tribe a lot, and this is also the stage of their life when they usually find their very first husband who is attracted by their skills and fully flourished beauty (as the extremely arched torso is considered highly attractive by the beauty standards of this tribe).