First Humans: The Cave Discovery

16 September 2015

 

This new documentary tells the fascinating inside story of an archaeological investigation that has discovered the remains of an entirely new species of human ancestor, Homo naledi.

The discovery grabbed headlines worldwide and is already re-writing the story of our origins and could transform the understanding of how modern humans evolved from ape-like creatures.

First Humans: The Cave Discovery (Channel 4, September 27th) has exclusive access to an expedition by an international team of experts, led by Paleoanthropologist Professor Lee Berger from the University of Witwatersrand, as they recover bone fragments from a deep and almost inaccessible cave in South Africa.

The documentary follows the whole story from the very beginning, when the remains were discovered by two amateur cavers, Rick Hunter and Steve Tucker, in 2013. Exploring a deep cave system called Rising Star near Johannesburg the pair found a hidden chamber, undiscovered by previous explorers.

Finding bones that looked human, the cavers took pictures and contact Lee Berger, a leading expert in the study of human origins. Berger, who has been searching for the remains of our early ape-like ancestors for two decades, was taken aback and immediately recognised that the bones came from some kind of hominid. “There were bones everywhere… I was a bit in shock,” he says in the programme. “These early human fossils are probably the rarest, sought-after objects on earth.”

The discovery could illuminate one of the great mysteries about our origins: how did we evolve from small-brained, ape-like Australopithicus into human beings? The period from two to three million years ago when this happened is probably the most important, but least understood, episode in our evolution. There is a gap in the fossil record, with only a few bone fragments, meaning that the cave find could be a treasure trove.

Berger decided to recruit a team of anthropologists capable of excavating the bones and bringing them safely to the surface. But as they lay deep underground, with the cave opening only eighteen centimeters wide, he put out a call for skinny scientists who weren’t claustrophobic.

An all-female team of six ‘underground astronauts’ was chosen to carry out the expedition in difficult and dangerous conditions, with Berger watching on the surface via remote cameras.

“The first thing that came through my mind was Howard Carter’s anecdote about opening Tutankhamen’s tomb,” says Marina Elliott, one of the underground excavating scientists. “It was Lord Carnarvon in the back saying, ‘What do you see?’ and Carter says, ‘Things, wonderful things’.”

The programme charts the huge challenge, carried out over several weeks, of recovering more than 1,500 bone fragments from the cave, including a skull and part of a jawbone with teeth still in place. Overall the team has so far found parts of at least fifteen individuals from the same species.

After the excavation, the scientists have to piece together and analyse the remains. Careful investigation reveals that the bones came from a never before seen species of human ancestor that they call Homo naledi – ‘naledi’ means ‘star’ in the local Sesotho language.

Naledi is a strange mosaic of ape and human, small brained and small bodied with chimp-like arms, but with human hands, teeth, small brows and long legs, probably a long-distance walker.

The remains show that human ancestry may be more complicated than we currently think. “We have a strong tendency to want to draw simple lines between species and make nice family trees, and we have to understand that is our need. That’s our desire. That’s not necessarily the way that nature works,” says paleoanthropologist Steve Churchill.

“We’re looking at creatures that are human-like in their feet, human-like in their hands, human-like in their teeth,” says paleoanthropologist Professor John Hawks. But the surprise for the experts is the size of Naledi’s brain. “It’s got an incredibly tiny brain. A brain that's more than a third as small as a modern human’s brain,” says Lee Berger.

But the thing that most surprises the team is where the bones were found. The fact that the cave is so inaccessible and that no bones from other animals were found leads the team to speculate that the bones may have been placed there intentionally and could even be evidence of a burial.

“If in fact the Rising Star hominins are purposefully disposing of their dead, we’re talking about some small-brained hominins who are doing this,” says Steve Churchill. “And that begins to change our thinking about sort of the cognitive attributes and the neural machinery that you need to engage in that kind of behavior. And that becomes really interesting.”

First Humans: The Cave Discovery will be shown on Channel 4 on September 27th at 8pm. The finds are described in two papers published in the scientific journal eLife and reported in National Geographic magazine.

Producer/Director: Graham Townsley

Executive Producer: Jared Lipworth

Production Company: National Geographic Studios and NOVA/WGBH Boston

Reversioned for Channel 4 by Quickfire Media