Stream It Or Skip It: ‘Unknown: Cave of Bones’ on Netflix, a Documentary Aiming to Blow Up Notions of What It Means to be Human

Unknown: Cave of Bones is the third in Netflix’s Unknown documentary series, which previously plumbed the mysteries of Egypt (Unknown: The Lost Pyramid) and scared us with world militaries’ use of artificial intelligence (Unnkown: Killer Robots). The film series is back to Indiana Jones territory with the latest entry, which follows paleontologist Lee Berger as he leads us through a terrifyingly narrow cave system in South Africa to show off his discovery: the 250,000-year-old bones of Homo Naledi, an ancient primate. Nifty, yes. But it’s potentially one of the most revealing paleontology digs ever, because it consists of a whopping 1,500 bone fragments belonging to 15 individuals, along with significant evidence that this species may have performed ritualized burials many, many thousands of years before Homo Sapiens (that would be us!) did such things. Which is significant, and may upend many things that we know about humans and their ancestors. 

UNKNOWN: CAVE OF BONES: STREAM IT OR SKIP IT?

The Gist: The Rising Star Cave is located in the Cradle of Humankind, a paleoanthropological locale chock-full of our biological ancestors’ remains. In that cave, Berger and his team unearthed what they seem somewhat terrified to admit might be a world-changer of a discovery: the first non-human species to exhibit “mortuary behavior.” Namely, there’s significant evidence that Homo Naledi brought fire into a pitch-dark cave, climbed steep inclines and crawled through deep holes to get to a specific spot, where they ritually buried their dead. They did it a quarter of a million years ago, which blows up the paleontological timeline; Homo Sapiens were considered to be the first to exhibit such behavior, 80,000 years ago. And they did it despite having smaller brains, which blows up the assertion that only species with big brains had the capacity for these kinds of cultural practices (cue a comment by one of Berger’s excavators, Dr. Keneiloe Molopyane, along the lines of “it’s not the size, it’s what you do with it”).

We over the shoulders of Berger, Molopyane, evolutionary anthropologist Augustin Fuentes and paleoanthropologist John Hawks as they nerd out hard over their findings, painstakingly brushing dirt off bones and later assembling them on a board like puzzle pieces. And then they extrapolate upon what it all means: Burying the dead is behavior spawning from relative psychological sophistication. It might mean Homo Naledi contemplated an afterlife, which would indicate the first glowing embers of religion. It might mean they couldn’t stand the thought of their family members or friends’ bodies decaying or picked apart by animals. It might mean they felt something like love. Fuentes compares this conjecture to the behavior of monkeys, who “grieve” their dead by lingering over bodies or carrying them around for a while, but they don’t discard them with the highly intentional behavior that Homo Naledi apparently did. The documentary offers us animated recreations of Homo Naledi rendered from charcoal or graphite sketches, eerie-but-fascinating best-guest approximations of how they might have looked. 

One tidbit: Berger was too large to fit through the cave corridors – one deep ascent is about, ulp, 7.5 inches wide – so he found smaller people to climb in and transmit video from the Homo Naledi “grave.” But by the end of the film, he’s donning the gear and squeezing down in there – he says he worked out and lost weight so, several years after he first discovered the site, he could finally look upon the findings with his own eyes. A camera atop his helmet documents his claustrophobic ascent, and when he reaches bottom, he says what anyone would say: “Holy. Crap.” 

What Movies Will It Remind You Of?: Cave of Bones goes as physically deep into the earth as Werner Herzog goes philosophically deep in Cave of Forgotten Dreams (which I know is a logically shoddy farther/further comparison, but just give me this one).

Performance Worth Watching: A little external research tells me that Berger is about as high-profile as paleontologists get (Time magazine once declared him one of the “100 most influential people”). His passion for his work is reflected in the wide-eyed enthusiastic demeanor among his research crew, and leads to a few hyperbolic declarations, but hey, you can’t blame them for being fired up by their discoveries.

Memorable Dialogue: “It’s exciting and a little bit scary at the same time.” – in prepping his first-ever descent to the burial site, Berger nutshells the eerie vibe of this entire story

Sex and Skin: None.

Our Take: The evidence Cave of Bones offers gives us a compelling glimpse into the life of ancient hominids, and into the process of scientific discovery. There’s a lot of talk about what it means to be human, and just as many reminders that Homo Naledi wasn’t human. Berger and co. insist that’s mind-blowing, and they’re persuasive. By the end of the film, they’ll make a couple more discoveries in the Rising Star Cave that’ll convince you that the title Unknown isn’t quite accurate in this instance. To paraphrase Regular Non-Baby Yoda, maybe it’s time to unlearn some of the things we’ve learned.

This is fascinating subject matter. But director Mark Mannucci (American Masters: Dr. Tony Fauci) doesn’t take a rigorous scientific approach to it here – he sticks wholly to the point-of-view of Berger and his crew, and never offers an outside perspective to either ratify or question his assertions, or to contextualize the findings. Are other paleontologists tearing up previously held timelines in light of this evidence? I found a 2015 PBS piece on Berger’s findings in Rising Star Cave in which other scientists accused him of “wild speculation” and characterized him as someone who “likes to tell a good story.” Cave of Bones shows us further evidence has been turned up since then, strengthening some of Berger’s basic assertions, but is the type of complex cultural behavior he describes a bridge too far? Maybe. (One hole I’d poke into the conjecture here: Has anyone considered the possibility that the earth may have shifted significantly in the last couple-hundred-thousand years, and the burial site may have been easier to access for Homo Naledi? Their journey through the cave may not have been so arduous. Cave of Bones spends more time staring at a map of a tortured underground route than any movie since the handful that were made about the Thai cave rescue.)

But the film sticks with Berger’s perspective, certainly because he’s an engaging personality, and because his findings are objectively unprecedented; when the film documents his first-ever descent into the deepest part of the cave, it loses focus and sort of becomes the half-assed story of this lifelong paleontologist’s personal journey. Mannucci tends to nurture a let-that-sink-in pace, lingering over this revelation and that bit of conjecture, and the film frequently repeats points as if to assert that we should be in absolute awe of all this stuff. Which we should be, to a point; I guess Unknown is an accurate title in the sense that we’ll never truly know if Homo Naledi experienced love or grief, or wondered if there was an afterlife. 

Our Call: We could nitpick the film’s structure and approach to the material, but Cave of Bones gives us some pretty enthralling science, and is an eye-opener either way. STREAM IT.

John Serba is a freelance writer and film critic based in Grand Rapids, Michigan.