A child's skull found deep inside a South African cave offers new clues about a group of mysterious human ancestors

An ancestor of Homo naledi, a human being, lived in southern Africa between 241,000 and 335,000.
Anthropologists discovered the first skull of a Homo Naledi child deep within a cave.

New research suggests that the skull's location in a remote area indicates that these ancestral burials were ritual.

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Marina Elliott and Becca Peixotto, anthropologists, found themselves trapped in a narrow tunnel nearly 300 feet below the ground four years ago. They were looking for ancient human remains in a network caves near Johannesburg, South Africa.

The pair walked through the cave, named Rising Star, using only their headlamps as guides. They climbed over boulders until they reached a narrow shaft. Peixotto prezeled her way around the corner, as only one person could go into the shaft at a given time.

They were there, on a limestone shelf. It was teeth and fragments from a skull belonging to a Homo Naledi child.

Homo Naledi, a mysterious human ancestor who lived around 250,000 years ago, is known as Homo Naledi. Peixotto is an American University researcher who has discovered bones from over two dozen naledi people in the Rising Star caves during the past eight years.

Marina Elliott, Anthropologist explores a tunnel within the Rising Star cave system. Wits University

These other remains were found in a chamber close to the skull. However, this latest discovery is unique, as it's the first ever infant naledi bone found according to a pair studies published on Thursday. Elliott, Peixotto and 17 other researchers co-authored one of the studies. It describes the exploration of the Rising Star System. The skull is described in a second paper.

Lee Berger, a University of Witwatersrand paleoanthropologist, co-authored both studies. He said that the skull could be used to teach experts about the development and growth of this species, who likely lived alongside modern humans.

The finding's remote location also offers clues to how the naledi dealt with their dead.

Berger stated that the child's body was most likely carried into the cave tunnel by its species. This means that the child could have been ritually buried, a behavior often seen in advanced human ancestors like Neanderthals or the earliest Homo sapiens.

Anthropologists called the child "the lost one"

Leti's skull is displayed by Lee Berger, an Anthropologist. Wits University

Researchers named the child Leti after the Setswana word for "letimela", which means "the lost one".

They found six teeth and 28 skull fragments, which they used to reconstruct Leti’s skull over the past four years.

The team couldn't identify Leti's gender because they didn't find any body parts. Children's bones break more easily than adults', and their skulls tend to be thinner so they are less durable.

Leti has six teeth. Wits University

Berger's team calculated Leti's age at four to six years using Leti's teeth. Teeth grow at a normal rate. The researchers also compared Leti's tooth size to that of young people.

The researchers also found that Leti's brain was similar to the brains of other members of its species, measuring up to 610 cubic cmimeters. This is about one-third of the brain size of an average modern human.

Debra Bolter, coauthor of the skull study, stated in a press release that "this would have been about 90% to 95% its adult brain capability."

Lee Berger holding Leti's skull reconstruction. Wits University

Researchers have not been able so far to pinpoint when Leti died.

Berger believed it to be about a quarter of a million years ago. The remains of adult naledi discovered in cave systems are between 241,000-335,000 years old.

Leti may have been placed in her final resting place by an 'upset parent'

To reach the cave where Leti's skull is found, Explorers had to squeeze through the narrow spaces of the Rising Star cave system. Wits University

There are many more possibilities for discoveries in the Rising Star's underground passages and rivers.

Leti was located just 40 feet from Dinaledi, a remote chamber where Elliott, Peixotto and Berger discovered the first naledi-fossil in 2013. Leti's burial site and difficulty in accessing Dinaledi suggest that the remains of the child may have been intentionally buried or placed there.

Juliet Brophy, who co-authored the skull study video, stated that "It's easy for you to imagine that you might have an upset parent would want to put this young person into its final resting places."

Leti's skull is also in good condition, which suggests that the body was safe from any scavengers.

Berger stated that his team will continue to search for more naledi dinosaurs in the Rising Star cave systems. He said that they will eventually be able to determine if these passages were used as burial grounds for the mysterious human ancestor.