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You remember Michael Shermer, right? One of his gigs is a regular column in Scientific American, and in a recent one he covers the potential find of a new hominin species.[1]

What triggered my skepticism, however, was the scientists’ conjecture that the site represents an example of “deliberate body disposal,” which, as the media read between the lines, implies an intentional burial procedure. […]

I believe the authors are downplaying an all too common cause of death in our ancestors—homicide in the form of war, murder or sacrifice.

Fair enough. On what grounds do you doubt the original authors’ conclusion, Shermer?

Lawrence H. Keeley, in War Before Civilization (1996), and Steven A. LeBlanc, in Constant Battles (2003), review hundreds of archaeological studies showing that significant percentages of ancestral people died violently. In his 2011 book The Better Angels of Our Nature, Steven Pinker aggregates a data set of 21 archaeological sites to show a violent death rate of about 15 percent. In a 2013 paper in the journal Science, Douglas P. Fry and Patrik Söderberg dispute the theory that war was prevalent in ancient humans by claiming that of the 148 episodes of violence in 21 mobile foraging bands, more than half “were perpetrated by lone individuals, and almost two-thirds resulted from accidents, interfamilial disputes, within-group executions, or interpersonal motives such as competition over a particular woman.” […]

Recall that after 5,000-year-old Ötzi the Iceman was discovered in a melting glacier in the Ötztal Alps in the Tyrol in 1991, it took a decade before archaeologists determined that he died violently, after he killed at least two other people in what appears to have been a clash between hunting parties.

Er, none of that references the original find. It does raise the prior probability that violence was involved, true, but you have to boost that quite some ways to comfortably render irrelevant all potential future evidence. It doesn’t help that Shermer seems unaware of why it took a decade to find evidence of violence.

Over the past decade, specialists have investigated just about every aspect of Ötzi’s body, from his tattoos to his stomach contents. Before he was moved to his own museum in Bolzano, Ötzi was scrutinised by Konrad Spindler and a team of experts at the University of Innsbruck in Austria.

Those tests included X-rays and CT scans, but no one spotted the arrow. “Everyone is very surprised that such an artefact could remain hidden for 10 years,” Spindler told New Scientist.

The arrowhead almost certainly eluded them because it lies between the shoulder bone and the ribs and would show only on a scan of Ötzi’s side. Spindler’s team scanned the body only from the front and back. “There’s a very small window through which to see it from the outside,” he says.

That mechanism only applies to mummies you want to keep intact, not skeletons laid bare. In the latter case, you’d need to find evidence of impact or trauma to the bones themselves. Shermer must then be proposing that the bone damage researchers found was due to person-on-person violence, and not some other factor.

We undertook a detailed taphonomic study of the surfaces and fracture patterns of the collection, led by Lucinda Backwell who is a world expert in the trace analysis of fossil remains. The bone in the collection is highly fractured and fragmented, but all of those fractures are consistent with breakage from static loading from sediment in the Dinaledi chamber. No fractures are indicative of a fresh, “green” fracture at or near the time of death. None of the bone fragments have traces of cutmarks or tooth marks that would result from butchery, disarticulation, percussion, or consumption of the remains. There are no cranial bone fragments with radiating fracture lines or signs of intentional breakage. In other words, none of the bone shows any traces that indicate that the individuals met a violent end.

Wait, the original researchers found no evidence for trauma?! If you read the original paper you’ll see they did some very extensive checking, to the point of cataloging damage by rodent teeth and beetle mandibles. While it’s theoretically possible more research could turn up something, I wouldn’t bet on it.

This is the simple answer to Shermer’s question, already available in our open access paper. The bones bear no trace of violence. So how did Shermer miss this evidence?

That’s John Hawks, one of the original researchers, and he has a pretty devastating explanation.

All respect to Carl Sagan, but he was wrong when he wrote, “Every kid starts out as a natural-born scientist, and then we beat it out of them.” I’ve spent a lot of time doing science outreach for kids of all ages. Scientists and children look at evidence very differently.

A kid looks at a problem by inventing the story that may lead to the problem. […]

A scientist looks at a problem by considering how to gather evidence to test hypotheses. One important part of science is recognizing that a story can be broken down into parts that can be tested with evidence.

The kids then thought of several ways to test some of their ideas, and I helped answer questions by pointing to the evidence in our research papers.

Ouch. Shermer does show some of the petty behaviour you expect from children, though.

Instead of publishing in Science or Nature, the prestigious journals in which major new fossil human finds are typically announced, the authors unveiled their discovery in eLIFE …, an open-access online journal that fast-tracks the peer-review process. And instead of meticulously sorting through the 1,550 fossils (belonging to at least 15 individuals) for many years, as is common in paleoanthropology, the analysis was published a mere year and a half after their discovery in November 2013 and March 2014.

Shermer dismisses the researchers’ work because they published in a smelly journal and didn’t hold their breath long enough. No need to reference what the researchers wrote or did, because it’s automatically wrong by association.

If Shermer is any guide, the process of skepticism is as follows:

  1. Look for something that might challenge what you know.
  2. Invent a story to explain it away.
  3. Bask in the glory of a job well done, and optionally remind people how smart and thoughtful you are.

 

[1] Dirks, Paul HGM, Lee R. Berger, Eric M. Roberts, Jan D. Kramers, John Hawks, Patrick S. Randolph-Quinney, Marina Elliott, et al. “Geological and Taphonomic Context for the New Hominin Species Homo Naledi from the Dinaledi Chamber, South Africa.” eLife 4 (September 10, 2015): e09561. doi:10.7554/eLife.09561.

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