Look at the shell below, which has been dated to 500,000 years ago. See the scratches? Those represent the oldest human etchings, or graffiti, ever found, preceding the next oldest by 300,000 years! Some anthropologists dissent, but more on that at the end of this post.
As Science reports, this shell was found by a graduate student Stephen Monro on Java in 2007, and now, 7 years later (yes, they studied it intensively), he and his colleagues have concluded not only that this was a human production—perhaps made by Homo erectus, who lived on Java at that time—but that they also used the shells as tools.
The full paper is in Nature, with the link and reference below (I believe it’s free). I’ll summarize what’s in the paper, and then go back to the Science report for a dissent by scientists.
The shell was part of an apparent cache of fossil mussel shells excavated in 1890 in Trinil, Java, which happens to be the type locality for Homo erectus, discovered by Eugène Dubois in 1891-1892 and originally called “Java Man“. (We’re not quite sure what happened to H. erectus: it could have interbred with expanding Homo sapiens populations coming from Africa beginning about 60,000 years ago, or it could have gone extinct without leaving descendants.) The dating of the shells from sediments enclosed in them gives an age of about 540,000 ± 10,000 years. Only H. erectus was in Java then.
The shells, too, were collected by Dubois, and, based on their uniform large size and the holes in them (see below), as well as other suggestive human modifications, were probably a midden of sorts left by H. erectus individuals who had eaten the mussels.
Now, the shells show three signs of modification by humans, including the “graffiti” above.
- They have holes drilled in them, likely by a human using a shark tooth. They are consistent in location and size, near the rear adductor muscle, and aren’t consistent with holes made by other predators like marine snails or otters. The authors found that you can make these holes with a shark tooth, and if it’s driven into just that spot in the rear, the mussel can’t use its muscle to keep the shell closed and opens, presenting its contents for food. Here’s a photo of the shell holes, presumably made by hominins (all species in our clade after we diverged from the lineage that produced modern chimps). The figure and caption are from the original paper. Similar holes were made by the native (pre-European) inhabitants of the Caribbean to open gastropods.
- Some of the shells appear to have been modified for use as cutting or scraping tools. Their outer layer was scraped off down to the nacreous (“pearl-like”) inner layer, making them sharp. These shells show wear patterns consistent with them having been used as tools.
- Most interesting, of course, is the graffiti: a poignant remnant of an early human (and yes, they suggest it was a single “person”). The journal’s description of this follows, along with another photo:
“One of the Pseudodon shells, specimen DUB1006-fL, displays a geometric pattern of grooves on the central part of the left valve (Fig. 2). The pattern consists, from posterior to anterior, of a zigzag line with three sharp turns producing an ‘M’ shape, a set of more superficial parallel lines, and a zigzag with two turns producing a mirrored ‘N’ shape. Our study of the morphology of the zigzags, internal morphology of the grooves, and differential roughness of the surrounding shell area demonstrates that the grooves were deliberately engraved and pre-date shell burial and weathering (Extended Data Fig. 5). Comparison with experimentally made grooves on a fossil Pseudodon fragment reveals that the Trinil grooves are most similar to the experimental grooves made with a shark tooth; these experimental grooves also feature an asymmetrical cross- section with one ridge and no striations inside the groove. We conclude that the grooves in DUB1006-fL were made with a pointed hard object, such as a fossil or a fresh shark tooth, present in the Trinil palaeoenvironment. The engraving was probably made on a fresh shell specimen still retaining its brown periostracum, which would have produced a striking pattern of white lines on a dark ‘canvas’. Experimental engraving of a fresh unionid shell revealed that considerable force is needed to penetrate the periostracum and the underlying prismatic aragonite layers. If the engraving of DUB1006-fL only superficially affected the aragonite layers, lines may easily have disappeared through weathering after loss of the outer organic layer. In addition, substantial manual control is required to produce straight deep lines and sharp turns as on DUB1006-fL. There are no gaps between the lines at the turning points, suggesting that attention was paid to make a con- sistent pattern. Together with the morphological similarity of all grooves, this indicates that a single individual made the whole pattern in a single session with the same tool.”
Here’s another figure showing this great specimen, along with its caption:
And finally, the paper’s conclusion, adding that the authors see this as the earliest use of a natural material to make tools.
The combined evidence for high-dexterity opening of shells, use of shell as a raw material to make tools, and engraving of an abstract pattern on a shell with a minimum age of 0.43 ± 0.05 Myr indicates that H. erectus was the agent responsible for the exploitation of freshwater mussels at Trinil described here. The inclusion of mussels in the diet of H. erectus is not surprising, as predation on aquatic molluscs is observed for many terrestrial mammals, including primates. The reported use of shells as raw material for tool production is the earliest known in the history of hominin technology. It may explain the absence of unambiguous stone artefacts in the Early and Middle Pleistocene of Java, possibly the result of poor local availability of lithic raw material, as also suggested for the much younger (about 110,000 years old) Neanderthal shell tools from Italy and Greece. Our discovery of an engraving on shell substrate is unexpected, because the earliest previously known undisputable engravings are at least 300,000 years younger.
Leaving aside the question of whether these “graffiti” are anything other than a hominin fooling around, or have a more symbolic meaning, there’s at least one anthropologist who takes issue with the claim that these patterns were made by H. erectus. As the Science report notes, the dating could be off, and the scratches made by more recent individuals of H. sapiens:
Yet even if ancient humans engraved the shell, says Russell Ciochon, a paleoanthropologist at the University of Iowa in Iowa City, the team has not shown that H. erectus did it. Ciochon, who has spent many years working at sites in Java, agrees with criticisms that the shells have been taken out of context, because Trinil was not an occupation site where early humans actually lived. Rather, Ciochon argues, the human fossils found there (which include a skullcap widely agreed to be H. erectus and a thigh bone that could belong to either H. erectus or H. sapiens,a matter of sharp debate) were washed into the site by a powerful flood, and nothing found with them—including the shells—can be assumed to have been associated with them originally. Although the team dated four of the shells in the collection, including the engraved shell, to about 500,000 years ago using two different techniques on sediments of sand and clay found inside them, Ciochon says that those sediments could have entered the shells during the earlier flood event that created the site, and that H. sapiens still could have come along much later and performed the etching.
I don’t have the expertise to judge how powerful this criticism is, but if it’s accurate, then the whole story goes out the window pending further study and excavation. But I like the H. erectus story, for, as Jake says to Brett in the last line of The Sun Also Rises, “Isn’t it pretty to think so?”
J. C. A. Joordens et al. 2014. Homo erectus at Trinil on Java used shells for tool production and engraving. Nature, published online, doi:10.1038/nature13962