It's not another tall tale: Evolutionary biologists have developed a new understanding of the genetic basis of short stature in humans. Also known as the pygmy phenotype, a study published Monday in the Proceedings of the National Academy of Sciences shows that this trait has evolved several times over the course of human history.

In the Central African rain forest, several groups of hunter-gatherers are significantly shorter than their agricultural neighbors are. Both the Batwa people in the east and the Baka in the west are commonly referred to as pygmies.

But exactly what factors were contributing to their reduced height wasn't clear. By analyzing the genomes of the Batwa and the Baka, and comparing them with the genomes of their