Murder in the Cave

Did Homo naledi behave more like Homo homicidensis?

“Fossil First: Ancient Human Relative May Have Buried Its Dead” (Reuters). “Why Did Homo naledi Bury Its Dead?” (PBS). These are just two of the many hyped headlines that appeared last September in response to a paper purporting the discovery, in a cave in South Africa, of a new species by paleoanthropologist Lee R. Berger of the University of the. There were reasons for skepticism from the get-go.

The age of the fossils is undetermined, so it is impossible to conclude where in the hominin lineage the fossils fit. Their hands, wrists and feet are similar to small modern humans, though slightly modified for an arboreal existence, and their brain volume is closer to that of the small-brained australopithecines, like Lucy, so it is not clear that this combination constitutes a new species or a variation on an existing species. Instead of publishing in a prestigious journal such as Science or Nature, for which the peer-review process can be lengthy, the authors opted for a fast-track publication in eLIFE (elifesciences.org/content/4/e09561), an open-access online journal. And instead of meticulously sorting through the 1,550 fossils (belonging to 15 individuals) for many years, as is common in paleoanthropology, the analysis was concluded in a mere year and a half after their discovery in November 2013 and March 2014.

What triggered my skepticism, however, was the scientists’ conjecture that the site represents the earliest example of “deliberate body disposal,” which, as the media read between the lines, implies an intentional burial procedure. This, they concluded was the likeliest explanation compared with four other hypotheses.

Occupation. There is no debris in the chamber, which is so dark that habitation would have required artificial light, for which there is no evidence, and the cave is nearly inaccessible and appears never to have had easy access. Water transport. Caves that have been inundated show sedimentological layers of coarse-grained material, which is lacking in the Dinaledi Chamber where the specimens were uncovered. Predators. There are no signs of predation on the skeletal remains and no fossils from predators. Death trap. The sedimentary remains indicate that the fossils were deposited over a span of time, so that rules out a single calamitous event, and the near unreachability of the chamber makes attritional individual entry and death unlikely.

Finally, the ages of the 13 individuals so identified— three infants, three young juveniles, one old juvenile, one subadult, four young adults and one old adult—are unlike those of other cave deposits for which cause of death and deposition have been determined. It’s a riddle, wrapped in sediment, inside a grotto.

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. In his 1996 book War Before Civilization, for example, archaeologist Lawrence Keeley estimates that as many as 20 to 30 percent of ancestral men died violently. In his 2003 book Constant Battles, archaeologist Steven LeBlanc reports that nearly every ancient human site shows signs of either armed conflict between groups, homicide between individuals within a group or cannibalism. 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 20 percent. In a 2013 paper in the journal Science, Douglas 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.”

Whatever you call it—war or murder—it is violent death nonetheless, and further examination of the Homo naledi fossils should consider violence (war or murder for the adults, sacrifice for the juveniles) as a plausible cause of death and deposition in the cave. Recall that after 5,000-year old Ötzi the Iceman was discovered in a melting glacier in the Tyrolean Alps 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. It’s a side of our nature we are reluctant to admit, but consider it we must when confronted with dead bodies in dark places.