Cave Of Bones Is Irresponsible For So Many Reasons

Cave Of Bones Is Irresponsible For So Many Reasons

Author’s Note: It feels odd to be putting out a post right now that, while important, feels relatively trivial compared to what is going on in Palestine right now. There is a US-sponsored genocide occurring as I write this. Both the United States and Israel want you to think the “situation” is “too complicated” for you to condemn genocide and apartheid. It is not. Please take the time to learn about the history of Israel and its violent colonization of Palestine. I hope to have blog posts sharing what I learn in these books—some of which are free right now—up in the near future and as a continual part of my blog.

Free Palestine. 🇵🇸

I just wanted to write a book review. But then Lee Berger had to go and shoot priceless fossils into space.

Cave of Bones: the book

I actually really liked Berger’s new book, Cave of Bones: A True Story of Discovery, Adventure, and Human Origins. Together with John Hawks, Berger picks up where he left off in his 2017 book Almost Human, in which the two had recounted Berger’s team’s 2008 and 2013 discoveries of ancient hominins Australopithecus sediba and Homo naledi.

I’ve been excitedly awaiting Cave of Bones since reading Almost Human in 2020 at the height of my hyperfixation on paleoanthropology. While my interests have since shifted into social justice and away from human evolution, I was curious to see what I’d missed in the past three years. I wondered what else Berger had run into in the mysterious Dinaledi Chamber where his team had first encountered the almost-human Homo naledi.

Cave of Bones is 208 pages long, but I found myself flying through it (a welcome change after my last slow read). I estimate that about 50% of the book’s real estate is actually words as opposed to pictures and blank space between chapters. It was admittedly a fun read, cataloguing in stomach-churning detail Berger’s squeezes through the tightest spaces imaginable to reach the beloved Dinaledi Chamber. Balancing these accounts were, of course, reports of what they found down there—and what those finds meant.

Did naledi bury their dead?

Berger had suggested in Almost Human that naledi may have buried their dead, or something like that. He had at the very least convinced himself that they intentionally disposed of bodies inside the Rising Star cave system that houses the Chamber. This was a monumental idea, as we otherwise have evidence of only Neanderthals and Homo sapiens ever burying their dead—hundreds of thousands of years later than naledi would have. Strangest of all? Homo naledi had a chimp-sized brain on a roughly human-sized body.

The claims in Cave of Bones get progressively wilder. Once Berger and his team were positive that naledi intentionally brought their dead all the way through this complex cave system, they realized that these hominids must have been able to see in the dark somehow. They must have used fire.

The evidence had massive implications, and Berger wanted to see up close what he had witnessed through a screen for years: the Dinaledi Chamber. He’d always known he wouldn’t be able to get down there himself. To reach the Chamber, explorers are forced to squeeze through the prohibitively narrow Chute, which gets down to only 19 cm (7.5 in) at its tightest point.

In 2022, Berger decided he didn’t care. He dieted on salads and eggs and was determined to make it inside.

The markings

That July, he came face to face with the entrance to the elusive Chamber for the first time. Almost at once he was struck by what he described ominously as “the markings” alongside a passage the size and shape of a doorway. He was stunned.

A slab of dolomite that Berger describes: "scratches and shapes, squares and triangles, lines that crossed over each other to form shapes resembling the letter A. There were crosses--some upside down, others right side up, at least to the modern eye. In the lower half of the rock panel was a square box. ... A series of ladderlike carvings ran down the left-hand side, and near the top was a shape like a fish with an X in it, the only nongeometric shape I noticed."

Many of the ancient doorways I’ve seen during the course of my career have borne ancient symbols or signatures that, long ago, shared information about what kind of space lay beyond. Much like our labels on doors for exits, sanctuaries, and even bathrooms, they help us know the function of the space we’re entering. So as the doorlike nature of the passage entry struck me, I couldn’t deny it. The markings were there on the wall.

. . .

I couldn’t believe what I was seeing. It looked to me as if the markings had clearly been made by hand. They were different from the natural weathering lines that form in hard dolomitic limestone. I was stunned. There should not be engravings in this chamber. Only humans make engravings. And to my knowledge, besides our explorers and a few previous cavers, no humans had ever entered here, certainly none with the time to make engravings like this in the very hard dolomite.

Lee Berger, Cave of Bones, pp. 151-153

Ruling out the marks being made by cavers or his team, or being naturally formed dolomitic “elephant skin,” Berger looked again at the marks using a black light and found himself in a trancelike, almost spiritual state of awe, as he watched the marks lift from the rock and float before him. He was especially struck by the etching near the top that he thought looked like a fish. He wondered why others on his team have never noticed these, but concluded that “It had to be Homo naledi” who made them.

Cave of bones and fire

After seeing the bones and sediment of Dinaledi up close, he noticed something else on his way out: “dark black dots” on stalactites, which he told his team, “That looks like soot and smoke damage to me.” Maybe his hypothesis that naledi saw in the dark by firelight was correct after all.

Actually, Berger tells us in Almost Human that the first explorers he had sent into the cave in 2013 had come back with photos “appearing to show chunks of charcoal” on the chamber floor, but Berger hadn’t been convinced. What he saw in 2022 was a different story.

One of the biggest questions that had eluded us to that point was also one of the most basic: How did naledi navigate these pitch-black spaces? But if what I was seeing was what I thought it was, the answer had been right above our heads the whole time. Naledi had brought fire into these spaces, and that fire’s smoke and ash had stained the limestone.

Lee Berger, Cave of Bones, p. 162

More engravings

We aren’t given much time to consider this evidence of fire. On the very next page, Berger sees yet another engraving, this time in the Dinaledi Chamber itself. This one consisted of more straight lines: cross-hatchings, crosses, and equal signs.

Cross-hatchings, crosses, and equal signs are all very human images, created to convey meaning in specific situations. It’s tempting to view markings like this through the modern lens of meaning, but if naledi had indeed etched these shapes, the artist would surely have different meaning behind it. Whatever these symbols signified or wherever they came from, be it from a single source or a combination of different hands, I couldn’t help thinking of the maker, or makers, as an artist working on a rock canvas.

Lee Berger, Cave of Bones, pp. 165-168

Overwhelmed with discoveries and overcome with emotion, it was time for Berger to struggle back up through the Chute. He paints himself a daredevil, bordering a hero—but reading about how he, with no exaggeration, almost died coming up the Chute, it’s hard to see him as anything but stupid and ridiculously lucky.

Three days of discoveries

Even then, Berger and team’s discoveries were not done. It seems that they never end. The next day, Berger goes back into the Dragon’s Back Chamber to witness the burnt animal bones, burnt charcoal, and ash layer that one of his senior researchers Keneiloe Molopyane (who I’ve been a big fan of for years) had uncovered the previous day while Berger was in the Dinaledi Chamber.

And the day after that, Berger, John Hawks, and Dirk Van Rooyen venture together into the Rising Star Chamber (which is a part of the Rising Star cave system, as are the Dinaledi and Lesedi Chambers. Berger and his team named all these areas and made them as confusing as they could.) In the Rising Star Chamber, Berger stumbles upon a once-in-a-lifetime discovery for the third day in a row: an intact hearth, complete with a floor “covered with burnt bones, ash, and big chunks of charcoal,” and even “something like a stick figure” “carved into the wall.”

Cave of grave goods

Perhaps the most radical idea in the book, though, is that Homo naledi used grave goods, or participated in “ritual burial with artifacts.” Berger and Hawks come to this conclusion when they get a CT scan done of a plaster cast their team made of a set of fragile fossils in the Dinaledi Chamber that they thought could have been a grave (albeit a grave that apparently held 3-4 individuals).

I had no words to express my amazement. John’s meticulous work on the CT scans had not only produced the most convincing picture yet of what might be a naledi burial; it had also revealed a possible stone tool within that burial. Our discoveries were growing more complicated—and more controversial.

Lee Berger, Cave of Bones, pp. 98-99

It did feel controversial, but I had no reason not to trust Berger, the expert. It all made sense to me: if naledi buried their dead so deep in the cave, then they must have made fire to see. If they made markings on the wall, then they must have had tools to do so. Was it likely, then, that they buried a fallen comrade together with a tool? Sure, why not.

Cave of Bones: the documentary

I started feeling truly suspicious when I watched the Unknown: Cave of Bones documentary on Netflix after closing the book. It was sensational. As a recovering paleoanth nerd, I loved seeing human evolution being celebrated. But for the same reason, I knew that nothing in paleoanth is ever as glamorous as the documentary made it out to be. The doc took us from “We found something underground. And it’s not human,” to, “These creatures buried their dead and made art,” to, “Did these beings have religion?” to “This changes everything we thought we knew about humanity and the origins of culture.”

I started to understand why Spotify had suggested a podcast episode to me called “Why Fossil Nerds Are Pissed Right Now.” I had first thought, “This couldn’t possibly be about Cave of Bones. Oh god, what are fossil nerds pissed about!?”

Oh, it absolutely was about Cave of Bones. Because what the hell was that.

  • A murky human like figure with a small head emerging from a yellow backlit doorway
  • The half human like, half ape like naledi holds a lit twig
  • Berger in his caving gear kneeling next to a small fire in the cave. He's looking down a pathway to where someone else is lighting yet another fire
  • An excavator is kneeling next to the half-buried remains of naledi. The longest part of the grave is barely wider than their knees, which are together
  • An artistic rendering of a naledi clan gathered around a burial, waving their arms in song
  • A naledi hand putting a stone tool into a fallen friend's hand during burial
  • A group of naledi singing at their friend's funeral, with artistic shadows on the cave wall behind them
  • A modern day religious leader

Bias in science?

Berger paints the greater scientific community as being skeptical toward his findings because they are biased towards large-brained humans—Homo sapiens and Neanderthals—as the only beings known to be capable of having culture or even of making complex hand tools. He says that “It was another scholarly assumption potentially threatened by our discoveries—specifically the tool-shaped stone in the Hill Antechamber burial.”

Scan of the tool thought to be a grave good

Well, fellow paleoanthropologists without emotional attachments to Homo naledi have since said that this large-brained bias is not why they don’t buy Berger’s claims. It’s because everything from the way that Berger and his team came to their conclusions, to the way that they presented those conclusions to the world, was wrong. All wrong. Actually, it stank.

The implications of the documentary are the tip of a stinky iceberg.

Why does peer review exist?

You have to have a basic understanding of the scientific publication and peer review process to know exactly what Lee Berger and his team did wrong here. It’s clear that Berger assumed that most documentary watchers and book readers don’t know this process. I certainly didn’t. But I’m not most readers. I hyperfixate on things that strike me as strange so that I can write extremely long blog posts about them.

Publishing a scientific paper—making a scientific claim—is supposed to mean something. Especially when it supposedly changes everything we know about humanity. That’s why scientific papers have a peer review process. It’s why we can be nearly positive that claims in scientific papers are legitimate: they’ve been tested by experts.

Every scientific paper needs to be peer reviewed before its claims are taken as fact, because no scientist is an expert in everything. Berger is an expert in hominid morphology. But his claims about Homo naledi, in the book at least, mostly hinge on him not knowing how else this or that would have got there if not for Homo naledi putting it there. He literally writes in Cave of Bones, “The absence of evidence is not evidence of absence.”

But it is, when we’re talking about scientifically proving things beyond reasonable doubt. You cannot declare a scientific discovery based off vibes when there are experts in ancient human burial, in the types of dirt and rock in these caves, and in virtually every detail of the findings.

Every single peer review of his findings at Dinaledi was negative.

The papers

We know this because Berger and his team published three papers, announcing unambiguously naledi’s burial practices, rock engravings, and cultural implications as preprints in the journal eLife (after being rejected by an unnamed leading journal) under its new “no-reject” model which will publish every paper it sent out for peer review. The catch? The peer reviews themselves are published alongside the paper. And Berger’s reviews were brutal.

(Thank you to the University of Iowa Library for access to these two Nature articles!)

Erika of the Gutsick Gibbon YouTube channel breaks down each and every review in this fantastic video. She, unlike me, is a PhD candidate who knows how to read scientific papers and peer reviews. If you’re interested, give her a watch, or feel free to read these on your own.

The timing

The really yucky part about it all is the timeline. The fact that Berger announced fire use before even sending the article about it for peer review is the first red flag that he wanted it to make a splash with the public before it started a hurricane in the scientific community. But going to four major media outlets, publishing a book, and creating a smash-hit Netflix documentary—all in less than a year after his only descent into the Chamber—to say in no uncertain terms that naledi buried their dead and made cave art, when there were no peer reviews that backed up his claims? The alarms were ringing. This was not rigorous science. This was a joke.

Fossils in space

Your eyes do not deceive you. Lee Berger sent Australopithecus sediba and Homo naledi fossils to the edge of space. In a billionaire’s pocket. In unmarked Ziploc bags. And the sediba fossil was a type specimen. This recklessness explicitly disregards the International Commission on Zoological Nomenclature’s recommendations for the preservation of type specimens.

This is even worse than it sounds. While scientists and commentators were upset about the unsubstantiated naledi media blitz for scientific and practical reasons, even more folks were furious about this publicity stunt for ethical and cultural, in addition to scientific, reasons. At best, it was unnecessary and irresponsible. Tim Nash, the fossil-wielding billionaire, was the fossils’ caretaker while on board the flight, which he spent floating about the cabin in low gravity.

At worst, African cultural scholar Dr. Mathole Motshekga told South African newspaper The Citizen, it was

…a violation of the constitutionally entrenched cultural and religious rights of our people.

We seem to have a big gulf and a clash of cultures when it comes to our ancestors. The black culture of worshipping ancestors is seen by Europeans as a sign of backwardness.

The departed are buried and live in spirit to look after those left behind… Taking their remains to space is a sign of utter disrespect – happening in a country where our traditional and cultural heritage should be sharing the same status as any other racial group.

Dr. Mathole Motshekga to The Citizen, Heritage Day debate: Clash over ancient human bones sent to space

The Human Tissue Act

“But these two species weren’t our ancestors,” you might say. Well, it’s interesting you would mention that. A British archeologist with the username Natsicle wrote a thread arguing that the artifacts sent on the space flight must have been classified as paleontological and archeological instead of being human remains because otherwise, a mysterious-sounding Human Tissue Act would have “kicked in and the idea would never have got off the ground.”

Archeologist Flint Dibble—that’s his real name!—echoed her sentiment more bluntly: 

While this would be irony of ironies, I wasn’t able to verify whether naledi’s non-humanness was something Berger had to argue in order to get the permit to export the fossils to New Mexico where they would be launched from. He actually calls naledi extinct humans in his application. South African Heritage Resources Agency (SAHRA) then grants him the export permit, with reference to it being allowed under the National Heritage Resources Act (NHRA). The only indication that the specimens were not being classified here as human is that the permit was signed by two individuals at SAHRA and not the Director-General of the South African National Department of Health, which would have been required, according to the Human Tissue Act, if Berger were to export human remains.

Reality is rarely as quippy as Twitter makes it out to be, at least from what I was able to find.


I can’t help but think the priceless-fossils-in-space shenanigans were a big Fuck You to the scientists who were frustrated over the unprofessional jumping to conclusions Berger did regarding naledi to gain easy views from a gullible public. It was his way of saying “I don’t care what you say, these fossils are mine, not yours!” It’s an interesting attitude to see coming from someone who has always been so against gatekeeping knowledge and specimens in paleoanthropology. How quickly Berger runs off to New Mexico—and space—with his fossils, one of which he found in a cave that only his team has authorization to go to and that most people couldn’t even fit into.

I’m not saying that Berger’s discoveries are illegitimate. I don’t doubt that his team found that treasure trove of Homo naledi skeletons in the Rising Star cave system. We have photos of the markings, the charcoal, and of course, the bones. It’s his hurry to make it all into a grand story about naledi singing and praying at loved ones’ funerals, before specialized experts even get to weigh in on what the evidence actually shows, that rings alarm bells. A Netflix documentary of paleoanthropologists saying, “I found something interesting, but peer reviewers doubt that it’s really a human burial, considering the grave is the size of a cat bed,” won’t get 6.5 million views in a week.

So if you came for only a Cave of Bones book review, then yeah, the book was good. It was a brief escape from reading about heavier topics like racism, homophobia, and Christian Nationalism. But it was too good to be true, and while he follows me now, it’s only a matter of time until Lee Berger blocks me, too.

9 thoughts on “Cave Of Bones Is Irresponsible For So Many Reasons

  • November 14, 2023 at 10:39 am

    Recently I read a NatGeo article about the Naledi cave. I was hoping it would be full of “what we found” and “what we have learned about what we found” but instead it was just about somebody’s personal challenges in squeezing into the cave. Too much about the author, not enough about the science.

    As tremendously exciting as the Naledi finds are, I’m disappointed that they aren’t being presented responsibly. They found charcoal. OK, but that doesn’t mean that Naledi used fire, it means that somebody used fire. Is there any reason to think that nobody else went into the caves between the Naledi burials and now? It would be great to have a book talking about how we can figure out how old the wall scratches and soot are, and how likely those are to be associated with the bones, but that doesn’t seem to be the book he wrote.

    • November 14, 2023 at 10:40 am

      Yeah, exactly. It was a gripping read about trying to fit through tight spaces. And he kept acting as if no one but naledi has ever been in there, when his first book said the first time they went in there, there was already a cave marker!

  • November 15, 2023 at 9:36 am

    I watched the documentary a few months ago and while I thought it was interesting and entertaining, I agree that some claims were definitely a bit too sensational.

  • November 15, 2023 at 2:55 pm

    This is a classic case of sensationalism over science. I would question the validity and interpretation of these findings if he didn’t want to discuss with his co-workers or if there was a problem with the peer review process. It seems like he sure knows how to write a good book though.

  • November 16, 2023 at 2:42 pm

    “I hyperfixate on things that strike me as strange so that I can write extremely long blog posts about them.” aren’t we’re glad you do! This was a great read and I’m saving the video to watch later, and share with my kids.

    • November 16, 2023 at 2:43 pm

      *and we’re glad you do. Anyways. Appreciate the amount of work that must have gone into this post!

  • January 7, 2024 at 9:23 am

    Your stance on Palestine makes your comments on everything else irrelevant.

  • February 24, 2024 at 8:13 pm

    I found this article after getting about 20 minutes into the Cave of Bones Netflix doc and something felt fishy and wanted to look into what other paleoanth experts opinions on the recent claims were. Years ago I watched the documentary about the initial discovery of naledi, which on its own is wildly fascinating, but the new doc felt like a circus. Couldn’t agree more with labeling Berger’s portrayals as irresponsible. At one point once he discovers the charcoal he immediately tells the viewer they now “likely have evidence” it was naledi which to another expert invites a huge amount of skepticism but to a causal viewer comes across as conclusive.

    Anyway loved your take and free Plaestine


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