Rising Star

On September 10, 2015, a new hominin species was announced that changed our understanding of human evolution. Homo naledi was discovered in the Dinaledi chamber of the Rising Star cave system at the Cradle of Humankind in South Africa. I and approximately 40 other early career researchers studied the over 1500 fossils excavated from this site and concluded that no species like this had ever been discovered. Homo naledi were tall (5’4”) but lightweight, small-brained but but with human-looking feet. The core of their bodies resembled our early ancestors in the genus Australopithecus, while their extremities more closely resembled humans.

My part of this research was to analyze the pelvic remains from the Rising Star cave. Over 40 pelvic fragments were found, and they represented individuals of different ages. I found that the pelvis was a mixture of primitive and more modern features. The top was primitive: instead of the bowl shape seen in humans, Homo naledi has a more saucer-shaped pelvis that is similar to Lucy’s. The bottom was more modern: the sitbones (ischia) were short, a trait shared with all members of the human genus. Despite these more modern traits, the pelvis is much more primitive than expected for a species of Homo.

Figure showing two views each of an ilium, ischium, and sacral fragment from the Rising Star fossil assemblage.

Selected pelvic specimens of H. naledi. U.W. 101-1100 ilium in (A) lateral view showing a weak iliac pillar relatively near the anterior edge of the ilium, with no cristal tubercle development; (B) anterior view, angled to demonstrate the degree of flare, which is clear in comparison to the subarcuate surface. U.W. 101-723 immature sacrum in (C) anterior view; and (D) superior view. U.W. 101-1112 ischium in (E) lateral view; and (F) anterior view, demonstrating relatively short tuberacetabular diameter. Scale bar = 2 cm.

The Rising Star fossils were extremely difficult to excavate because they were deposited, perhaps purposefully, in a dark hard-to-reach chamber where no other animals would disturb them. How did a small-brained, somewhat primitive member of the human genus manage such a feat? We currently do not know, but are looking forward to the challenge of finding out. Homo naledi forces paleoanthropologists to reconsider a number of truths we thought were set in stone: depositing bodies may not be a uniquely human behavior; a humanlike pelvis and upper body are not a defining feature of our genus; and the evolution of humans is a more complex story than we could have ever predicted.

My research on Homo naledi:
Learn more about Homo naledi:
Media where I discuss Homo naledi and the Rising Star project: