Two recent Netflix documentaries have ignited a firestorm among members of the scientific community who have challenged the credibility of the work.

The popular shows are “Unknown: Cave of Bones,” which explores what could be the world’s oldest graveyard, and “Ancient Apocalypse,” about an advanced civilization hypothesized to have gone extinct around the last ice age. Each made the Netflix global top 10 list when they debuted in July 2023 and November 2022, respectively.

But many archaeologists and anthropologists—in critiques published in scientific journalsacademic and professional websites, YouTube videos, and a letter to Netflix—argue the shows promote theories that don’t represent a scientific consensusand shouldn’t be labeled as documentaries.

Netflix declined to comment.

The conflict raises questions about the responsibility media companies have for the content they commission and distribute and about the influence that content has on the public’s evolving understanding of science. Filmmakers and stars of the shows defend the productions, saying the established research community is too wedded to the peer-review framework as a means of communicating science.

It wasn’t about making a “peer-reviewed journal of a film,” said Mark Mannucci, director and producer of “Cave of Bones.” “There’s a tone that I hope we were able to imbue this film with, where these scientists are really asking questions, as opposed to making statements that sound like they’ve nailed it.”

British journalist and author Graham Hancock, who hosted “Ancient Apocalypse,” said the series tells a story he passionately believes in. “At the end of the day, the public is the final arbiter,” Hancock said. “Fortunately, the public seems to have liked this series very much indeed.”

Viewers watched episodes of “Ancient Apocalypse” for almost 36 million hours between January and June of last year, according to a Netflix engagement report released in December. Figures for “Cave of Bones” haven’t yet been released.

Netflix has nearly 250 million paid memberships in more than 190 countries, according to Securities and Exchange Commission filings, and the documentary category is one of the streaming platform’s fastest-growing genres, a 2022 study by researchers in Brussels found.

The extent of that reach, scientists say, should compel the company to ensure the veracityof material it markets as documentaries.

“Organizations like Netflix have an editorial responsibility,” said John Hoopes, a University of Kansas archaeologist.

But the definition of documentary has become more flexible, said Marcia Rock, director of news and documentary at New York University’s Arthur L. Carter Journalism Institute.

“Nonfiction on television has the same challenges as fiction on television,” she said. “You need tension and a story arc.” Rock, who wasn’t involved with the show, said “Ancient Apocalypse” makes it clear that Hancock’s theories don’t align with the established consensus. That is sufficient, she added.

“Ancient Apocalypse” explores whether an advanced civilization coexisted with hunter-gatherers across the globe before going mostly extinct around 12,000 years ago. This civilization, the show contends, was responsible for the knowledge that enabled the spread of agriculture and the construction of ancient architectural wonders, rather than the indigenous people archaeologists generally credit for the developments.

In the show, Hancock suggests this lost civilization enabled the construction of pyramids in Mexico and Indonesia, stone temples in Micronesia and Malta, and raised mounds in the southern U.S., among other structures. He says an underground city in modern-day Turkey might have once housed this civilization. He also points to a submerged geological feature in the Bahamas known as the Bimini Road, or Bimini Wall, as potential evidence of its road-building.

Typically, previous civilizations are documented by archaeologists who unearth tools, writings, carvings and monuments and then use techniques such as radiocarbon dating to gauge the age of the artifacts and structures.

Established archaeological dates based on these techniques indicate structures Hancock links to an advanced civilization were built thousands of years after he says that civilization went extinct. Geologists say the Bimini Road is a naturally occurring rock formation. Hoopes, University of Maine archaeologist Daniel Sandweiss and many other researchers say there is no material evidence that a civilization like the one Hancock describes ever existed.

“We can find hunter-gatherer camps that are 12,000 years old,” said Charles Ewen, a professor of anthropology at East Carolina University. “They’re hard to find, but we’ve got lots of them. And yet we can’t find any direct evidence of this past civilization.”

Hancock said that many coastlines were submerged following the last ice age and that archaeologists haven’t fully explored all areas for evidence of this advanced civilization’s existence. Sea levels rose by 400 feet following the end of the last ice age, according to the U.S. Geological Survey.

Upon the show’s release, Sandweiss, also the president of the Society for American Archaeology, wrote to Netflix on behalf of the group’s more than 5,500 members and called for the streaming platform and the show’s production company to describe “Ancient Apocalypse” as science fiction.

Hancock published a rebuttal to the letter on his personal website. Netflix and the production company, ITN Productions, didn’t respond to the letter, according to Sandweiss. ITN Productions didn’t respond to The Wall Street Journal’s requests for comment.

In “Cave of Bones,” paleoanthropologist Lee Berger maintains that extinct human relatives named Homo naledi—with a brain the size of an ape’s—buried their dead in shallow graves in a subterranean cave system in South Africa, where they also carved symbolic wall art by the light of ancient torches.

Anthropologists typically ascribe such behaviors only to modern humans and our extinct Neanderthal cousins, which had brains about three times bigger than those of Homo naledi. Evidence of burials and meaningful art in smaller-brained relatives would upend longstanding views of what it means to be human.

“There is no doubt when you look at it from here,” Berger, a National Geographic Explorer in Residence with an appointment at Wits University in Johannesburg, says in the film when examining what he says is a Homo naledi grave.

Cardiff University archaeologist Flint Dibble, who published a critique of “Cave of Bones” on YouTube, and other scientists told the Journal that Berger and his team haven’t presented enough evidence to support that the burials he discusses in the film were intentionally dug and not the result of natural processes, such as erosion.

There are existing criteria that can help identify a burial, Dibble said, including asserting whether a hole is handmade or natural, whether that cavity is intentionally filled and whether a skeleton is articulated, meaning the bones remain together and arranged in the proper order.

Berger said the bones from the only burial to have been removed from the cave system, named Rising Star, and examined using CT scanning belong to the same individual.

But based on the findings that have been shared, the skeleton isn’t fully articulated, according to Paul Pettitt, a professor of Paleolithic archaeology at Durham University in the U.K. “There’s a bit of an articulated limb here and an articulated foot there and an articulated hand there,” he said, suggesting “these are body parts that are being washed around.”

Previous geological studies have shown the sediment inside Rising Star is subject to erosion, drainage, and what experts call slumping, or downhill movement. Pettitt, who published a commentary examining claims regarding Homo naledi’s funerary activities, said such processes could have moved the bodies around inside the system’s many chambers, and buried them.

Berger also says in the film that what appear to be engravings on one of the cave walls, including crisscross patterns and geometric shapes, meaningfully mark the entrance and exit of a passage. The act of engraving intentional designs with stone tools is widely considered by paleoanthropologists to be a major cognitive step in human evolution.

The features on the wall, which resemble symbolic art made thousands of years later by Neanderthals and Homo sapiens, haven’t been dated by Berger and his colleagues and might not have been made by Homo naledi, according to Andy Herries, a professor of paleoanthropology at La Trobe University in Melbourne, Australia. Similarly, evidence put forth by Berger’s team that Homo naledi used fire—such as hearths with charcoal and charred wood—hasn’t yet been dated.

“If you want to sit there and say you have a [Homo] naledi-made fire, well then in the first place, radiocarbon date your charcoal,” said Herries, who co-wrote a recent paper in the Journal of Human Evolution critiquing Berger and his team’s conclusions. “Show us how old it is.”

Berger said efforts to date the hearths and other evidence for fire in the cave system are ongoing.

Questions about Berger’s Homo naledi research arose before the release of “Cave of Bones,” when his group shared their findings about the species’ mortuary practices and art in a trio of preprint papers.Typically, scientific studies are subject to rigorous scrutiny by outside experts in the field before publication. The findings received significant media attention at the time of their initial publication in June, including in the Journal.

The preprints were subsequently published in the peer-reviewed journal eLife, whose editors and reviewers in an assessment accompanying the work concluded that the evidence presented was “incomplete at this stage.”

The stars of both Netflix shows chafe at the criticisms from the scientific community.

“What I see happening now is people are angry that we’re actually publishing hypotheses for almost the first time in the history of this field,” Berger said, adding that his team believes they are putting forward the best hypotheses about Homo naledi’s behavior based on the evidence they have.

“Cave of Bones” executive producer Jon Bardin said he and Mannucci, the film’s director, sought to showcase the anthropologists’ experiences and the excitement of the discovery process.

“We can’t say something on screen that is factually incorrect,” Bardin said. “That’s different than pushing everything through the scientific method.” Bardin is head of documentary and nonfiction at Story Syndicate, the production company from which Netflix commissioned “Cave of Bones.” The Journal partnered with Story Syndicate in the production of a documentary about GameStop.

The lesson for researchers who want to hold platforms like Netflix to a higher scientific standard, Pettitt said, is that they must start a serious conversation with the people who commission and produce these shows.

Ewen, the East Carolina University anthropologist, agreed. “How we win people over is by being better at telling our stories.”

Write to Aylin Woodward at