Scientists have uncovered the shattered skull of a Homo Naledi infant named “Leti” deep beneath South Africa’s Rising Star cave system, in a dark tube only 6 inches (15 cm) wide. It’s unclear how the little skull wound up in such a distant portion of the cave, but the discoverers believe it might be proof of deliberate burial.
Based on the dates of other bones discovered in the mysterious cave, “Leti,” short for “Letimela” or “Lost One” in the Setswana language of South Africa, lived between 335,000 and 241,000 years ago. Since 2013, when the first fossils from this human progenitor were discovered in what is now known as the Dinaledi Chamber, roughly 24 Homo Naledi individuals’ fossil pieces have been discovered in the cave system.
The presence of so many members of a single species in the cave is puzzling. The only route in is through a 39-foot (12-meter) vertical fissure known as “The Chute,” and geologists and spelunkers have found no indication of other entries into the passages. Leti’s little skull was discovered in pieces on a limestone shelf approximately 2.6 feet (80 cm) above the cave floor. The location is located amid “a spiderweb of confined corridors,” according to Maropeng Ramalepa, a member of the exploring team.
A Difficult Ancestor
According to new research published Thursday (Nov. 4) in the journal PaleoAnthropology, the region is scarcely passable for expert spelunkers using contemporary equipment. There is no indication that animals brought the H. Naledi bones into the cave – no gnaw marks or predation signs. Because the bones were not found intermingled with dirt or other detritus, they appear to have been deposited in the cave rather than washed in.
That opens the door to the idea that more than 240,000 years ago, human ancestors with orange-sized brains purposefully entered a dark, maze-like cave, maybe by a vertical chute that narrows to 7 inches (18 cm) in parts, and buried their dead there.
Outside the Rising Star cave system, anthropologist Lee Berger (right) displays Leti’s skull. Wits University is the photographer.
There were no tools or artifacts discovered besides the Rising Star cave system fossils. Aside from two young baboons, at least one of which may be substantially older than the Homo Naledi bones, there are scant traces of other creatures visiting the caves.
According to John Hawks, an anthropologist at the University of Wisconsin-Madison who examines the bones, this human progenitor lived at the same time as early Homo sapiens. Their apparent treks inside the cave indicate that they were among modern humans’ wiser progenitors and that they had mastered the use of fire to illuminate their investigations, according to Hawks. H. Naledi walked erect, stood approximately 4 feet, 9 inches (1.44 m) tall, and weighed between 88 and 123 pounds, according to the Smithsonian National Museum of Natural History (about 40 and 56 kilograms).
The new skull, which fits in the palm of a modern human hand, should disclose more about the growth and evolution of H. Naledi. While researchers have recovered a few jaw fragments from youngsters in the cave, this is the first time they have unearthed bones from the skull case or cranium. Six teeth were also discovered.
Teeth and Bones
The bones and teeth were discovered while exploring the tight, twisting corridors surrounding Dinaledi Chamber. Researchers surveyed 1,037 feet (316 m) of these corridors in search of evidence of another entry into that chamber and others nearby where remains have been discovered. They found no indication of a different path.
Leti has six incisors. Wits University is the photographer.
“Exploration of the narrow passages within the Dinaledi Subsystem requires considerable effort, navigating areas with irregular floors and walls, numerous obstructions and fissures less than 30 cm [11.8 inches] wide,” wrote archaeologist Marina Elliott of Simon Fraser University in British Columbia, Canada, in a paper published in PaleoAnthropology.
However, the researchers discovered additional fossils in this underground labyrinth. The second-ever piece of evidence of a juvenile baboon in the cave; a single-arm bone that most likely belonged to H. Naledi; a hoard of 33 bone pieces that also most likely belonged to an H. Naledi individual or individuals; and Leti. Leti’s skull details were also published in the journal PaleoAnthropology on November 4th.
The partially preserved skull was dismembered into 28 pieces. When these fragments were rebuilt, they revealed most of the child’s forehead and some of the top of the skull. There were four unworn permanent teeth and two worn baby teeth among the teeth. Their growth and wear show that the youngster was about the age when the first permanent molars broke through the gum. This corresponds to around 4 to 6 years of age in a human kid. It is unknown whether H. Naledi evolved quicker; if so, Leti may have died while he or she was younger than four years old.
Lee Berger is holding a replica of Leti’s skull. Wits University is the photographer.
Leti’s brain has a capacity of between 29 and 37 cubic inches (480 and 610 cubic cm) based on the size of her skull, which is around 90% to 95% of the brain volume of adults of her species.
“This begins to provide us insight into all stages of life of this amazing species,” said Juliet Brophy, an anthropologist at Louisiana State University who conducted the study on Leti’s skull, in a release.