The Pygmies' Small Stature, do they evolve?

The small body size of pygmy people has long attributed to nutritional deficits resulting from harsh living conditions of the rainforest. However, a new study suggests that the human pygmy trait has genetic basis and has in fact evolved several times in different populations.

Researchers focused on the Batwa pygmy people of Uganda’s Bwindi Impenetrable Forest, comparing them to their taller neighbors, the Bakiga people. These ones (Bakiga) are taller than Batwa but they have a similar nutrition and live in a similar environment and often intermarry.

They analyzed the genome of both groups and the results revealed 16 different genomic locations associated with phenotype. These variations are related with human growth hormone and bone formation. Moreover, people with more Bakiga genes at these locations were taller.

From these findings a new question comes up: do all human pygmies have a common ancestor? In order to answer it, researchers took DNA samples from another pygmy tribe in west central Africa, called Baka. If the pygmy phenotype originated from a common ancestor, then the genomes of the Baka and Batwa would vary in the same ways. However, the two tribes’ pygmy genes were different. So this means that, pygmy traits evolved independently in these two populations likely in many different populations around the world.

Researchers suggest that pygmy mutations were beneficial in order to live in a rainforest they spread. For instance, been shorter in the rainforest is advantageous because the body generates less heat, need less food…

More study will be needed to determine just how environment influences the pygmy’s stature.