The Chamber of Stars
In 2013, recreational cavers exploring the Rising Star cave system, part of South Africa's Cradle of Humankind World Heritage Site, squeezed through a narrow, 12-meter-long vertical chute and entered a previously unknown chamber 30 meters underground. The floor was littered with bones. This discovery led paleoanthropologist Lee Berger to assemble an expedition that recovered over 1,550 fossil specimens, the largest single assemblage of a hominin species found in Africa. The remains belonged to at least 15 individuals of a new species: Homo naledi.
Accessing the Dinaledi Chamber ("Chamber of Stars" in the Sesotho language) was extraordinarily difficult. The narrowest passage is a mere 18 centimeters (7 inches) wide, requiring a specialized excavation team. Berger recruited six slender female scientists with caving and paleontological experience, who became known as the "Underground Astronauts." The chamber contained no other large animal fossils and the bones showed no signs of predator damage, which ruled out the chamber being a carnivore's den or a natural trap. The remains included males and females of various ages, from infants to elderly adults, representing a snapshot of a population.
An Evolutionary Puzzle
Homo naledi has a mix of ancient and modern anatomical features. Its brain was small, with a cranial capacity between 465 and 610 cubic centimeters—not much larger than a chimpanzee's. The shoulders, torso, and pelvis were similar to more primitive australopithecines. Yet, its wrists, hands, legs, and feet were remarkably human-like. Standing at an average height of 1.46 meters (about 4 ft 9 in) and weighing around 40 kilograms (88 lbs), Homo naledi had long, curved fingers well-suited for climbing.
The discovery came from dating the fossils. Initially, the primitive features suggested an age of one to two million years. Multiple dating techniques placed the remains between 335,000 and 236,000 years old. This means Homo naledi was a contemporary of early Homo sapiens in Africa.
The placement of so many individuals deep within a nearly inaccessible cave system shows intentional deposition of the dead. This behavior, a form of complex ritual, was previously thought to be exclusive to large-brained hominins like Neanderthals and modern humans. The existence of a small-brained species performing such acts updates our understanding of the cognitive abilities of early human relatives. More recent and debated claims from the research team also propose the discovery of intentional burials in shallow pits, the use of fire for illumination, and rock engravings within the cave system, although these interpretations face ongoing scientific scrutiny.