Fun fact: each year, people around the world purchase 50 billion dollars’ (US) worth of adhesives. But perhaps this statistic isn’t all that surprising—because almost everything we make includes some type of bonding agent.
In the context of human prehistory, anthropologists consider adhesives to have been a transformative technology. They would have provided the first humans the means to construct new types of complex devices and combine different types of materials (composites) into new technologies.
Anthropologists also consider the production and use of adhesives to be a diagnostic of advanced cognitive capabilities, such as forward planning, abstraction, and understanding of materials. Production of adhesives from natural sources, even by the earliest modern humans, appears to have been a complex operation, requiring precise temperature control and the use of earthen mounds, or ceramic or metal kilns. The first large-scale production of adhesives usually centered around the dry distillation of birch and pine barks to produce tar and pitch.
Even though modern humans perfected dry distillation methods for tar production, the archaeological record seemingly indicates that it wasn’t modern humans who first manufactured adhesives from tar, but, instead, Neanderthals. The oldest evidence for tar production and use dates to around 200,000 years ago, based on organic residues recovered from a site in Italy. It appears that Neanderthals were using the tar as glue for hafting flint spearheads to wooden spear shafts.1 Archaeologists have also unearthed spearheads with tar residue from two sites in Germany dating to 120,000 years in age and between 40,000 to 80,000 years in age, respectively.2 Because these dates precede the arrival of modern humans into Europe, anthropologists assume the tar at these sites was deliberately produced and used by Neanderthals.
For some anthropologists, this evidence indicates that Neanderthals possessed advanced cognitive ability, just like modern humans. If this is the case, then modern humans are not unique and exceptional. And, if human beings aren’t exceptional, then it becomes a challenge to defend one of the central concepts in Scripture—the idea that human beings are made in God’s image. Yet, claims that Neanderthals are cognitive equals to modern humans fail to withstand scientific scrutiny, time and time again. (See Resources section below.) This, too, is the case when it comes to Neanderthal tar production.
How Did Neanderthals Extract Tar from Birch Bark?
Though it appears that Neanderthals were able to produce and use tar as an adhesive, anthropologists have no idea how they went about this task. Archaeologists have yet to unearth any evidence for ceramics at Neanderthal sites. To address this question, a team of researchers from the University of Leiden conducted a series of experiments, trying to learn how Neanderthals could dry distill tar from birch bark using the resources most reasonably available to them.
The research team devised and evaluated three dry distillation methods:
- The Ash Mound Method: This technique entails burying rolled up birch bark in hot ash and embers. The heat from the ash and embers distills the tar away from the birch bark, but because the bark is curled and buried, oxygen can’t easily get to the tar, preventing combustion.
- The Pit Roll Method: This approach involves digging a cylindrical pit and then placing a burning piece of rolled-up birch bark in the pit, followed by covering it with earthen materials.
- The Raised Structure Method: This method involves placing a vessel made out of birch bark in a pit, igniting it, and covering it with sticks, pebbles, and mud.
Of the three methods, the researchers learned that the Pit Roll technique produced the most tar and was the most efficient method. Still, the amount of tar that was produced was not enough for large-scale use, but just enough to haft one or two spears at best. The tar produced by all three methods was too fluid to be used for hafting.
Still, the research team concluded that Neanderthals could have dry distilled tar from birch bark, using methods that were simple and without the need to precisely control the distillation temperature. They also conclude that Neanderthals must have had advanced cognitive abilities—on par with modern humans—to pull off this feat.
Did Neanderthals Have Similar Cognitive Capacity to Modern Humans?
Does the ability of Neanderthals to dry distill tar (using crude methods) and use it to haft spears reflect sophisticated cognitive abilities? From my vantage point, no.
The recognition that the methods Neanderthals most likely used to dry distill tar from birch bark didn’t require temperature control and were simple and crude argues against Neanderthal sophistication, not for it. To this point, it is worth noting that birch bark naturally curls, a factor critical to the success of the three dry distillation methods explored by the University of Leiden archaeologists. In other words, curling the birch bark was not something Neanderthals would have had to discover.
It is also worth pointing out that recent work indicates that Neanderthals did not master fire, but instead made opportunistic use of fire. These creatures could not create fire, but, instead, harvested wildfires. There were vast periods of time during Neanderthals’ tenure in Europe when wildfires were rare because of cold climatic conditions, meaning Neanderthals didn’t have access to fire. Because fire is central to the dry distillation methods, Neanderthals would have been unable to extract tar and use it for hafting for a significant portion of their time on Earth. Perhaps this explains why recovery of tar from Neanderthal sites is a rare occurrence.
Still, no matter how crude the method, dry distilling tar from birch bark seems to be pretty remarkable behavior—until we compare Neanderthal behavior to that of chimpanzees.
Comparing Neanderthal Behavior to Chimpanzee Behavior
In recent years, primatologists have observed chimpanzees in the wild engaging in some remarkable behaviors. For example, chimpanzees:
- manufacture spears from tree branches, using a six-step process. In turn, these creatures use these spears to hunt bush babies
- make stone tools that they use to break open nuts
- collect branches from specific trees with appropriate mechanical characteristics and insect-repellent properties to build beds in trees
- collect and consume plants with medicinal properties
- understand and exploit the behavior of wildfires
In light of these remarkable chimpanzee behaviors, the manufacture and use of tar by Neanderthals doesn’t seem that impressive. No one would equate a chimpanzee’s cognitive capacity with that of a modern human. And, likewise, no one should equate the cognitive capacity of Neanderthals with modern humans. In terms of sophistication, complexity, and efficiency, the tar production methods of modern humans are categorically different from those of Neanderthals, reflecting cognitive superiority of modern humans.
Do Anthropologists Display a Bias against Modern Humans?
Recently, in a New York Times article, science writer Jon Mooallem called attention to paleoanthropologists’ prejudices when it comes to Neanderthals. He pointed out that the limited data available to these scientists from the archaeological record forces them to rely on speculation. And this speculation is inevitably influenced by their preconceptions. Mooallem states,
“All sciences operate by trying to fit new data into existing theories. And this particular science [archaeology], for which the “data” has always consisted of scant and somewhat inscrutable bits of rock and fossil, often has to lean on those metanarratives even more heavily. . . . Ultimately, a bottomless relativism can creep in: tenuous interpretations held up by webs of other interpretations, each strung from still more interpretations. Almost every archaeologist I interviewed complained that the field has become “overinterpreted”—that the ratio of physical evidence to speculation about that evidence is out of whack. Good stories can generate their own momentum.”3
Mooallem’s critique applies to paleoanthropologists who are “modern human supremacists” and those with an “anti-modern human bias” that seeks to undermine the uniqueness and exceptionalism of modern humans. And, lately, reading the scientific literature in anthropology, I get the strong sense that there is a growing anti-modern human bias among anthropologists.
In light of this anti-modern human bias, one could propose an alternate scenario for the association of tar with flint spearheads at a few Neanderthal sites that comport with the view that these creatures were cognitively inferior to modern humans. Perhaps Neanderthals threw birch or pine into a fire they harvested from a wildfire. And maybe a few pieces of bark or some pieces of branches near the edge of the fire naturally curled, leading to “dry distillation” of small amounts of tar. Seeing the tar exude from the bark, perhaps a Neanderthal poked at it with his spear, coating the piece of flint with sticky tar.
When we do our best to set aside our preconceptions, the collective body of evidence indicates that Neanderthals did not have the same cognitive capacity as modern humans.