The Khoe-San people of southern Africa, who speak a language based on clicking sounds, are descendants of the most ancient genetic split found yet in living humans, finds an international group of scientists.
The results also reveal some of the evolutionary changes that helped give rise to modern humanity.
Anatomically modern humans (us), evolved about 200,000 years ago in Africa. Differences between people living today and our evolutionary relatives include much less pronounced eyebrow ridges and larger brains.
Much remains uncertain about how modern humans originated in Africa's cradle of humanity. For instance, researchers had long thought humans arose in eastern Africa, but recent studies hint at roots in southern Africa. [Image Gallery: Our Closest Human Ancestor]