One time when our kids were little, my wife and I discovered that someone had drawn a picture on one of the walls in our house. Though all of our children professed innocence, it was easy to figure out who the culprit was, because the little artist also wrote the first letter of her name on the wall next to her “masterpiece.”
If only archaeologists had it as easy as my wife and me when it comes to determining who made the ancient artwork on the cave walls in Europe. Most anthropologists think that modern humans produced the art. But, a growing minority of scientists think that Neanderthals were the artists, not modern humans. If anthropologists only had some initials to go by.
In the absence of a “smoking gun,” archaeologists believe they now have an approach that will help them determine the artists’ identity. Instead of searching for initials, researchers are trying to indirectly determine who the artists were by dating the cave art. They hope this approach will work because modern humans did not make their way into Europe until around 40,000 years ago. And Neanderthals disappeared around that same time. So, knowing the age of the art would help narrow down the artists’ identity.
Recently, a team from the UK and Spain have applied this new dating method to art found in the caves of Iberia (southwest corner of Europe). And based on the age of the art, they think that the paintings on the cave walls were produced by Neanderthals, not modern humans.1
Artistic expression reflects a capacity for symbolism. And many people view symbolism as a quality unique to human beings, contributing to our advanced cognitive abilities and reflecting our exceptional nature. In fact, as a Christian, I see symbolism as a manifestation of the image of God. Yet, if Neanderthals possessed symbolic capabilities, such a quality would undermine human exceptionalism (and with it the biblical view of human nature), rendering human beings nothing more than another hominin.
Limitations of Dating Cave Art
Dating cave art is challenging, to say the least. Typically, archaeologists will either: (1) date the remains associated with the cave art and try to establish a correlation, or (2) attempt to directly date the cave paintings using carbon-14 measurements of the pigments and charcoal used to make the art. Both approaches have limitations.
In 2012, researchers from the UK and Spain employed a new technique to date the art found on the walls in 11 caves located in northwest Spain.2 This dating method measures the age of the calcite deposits beneath the cave paintings and those that formed over the artwork, once the paintings had been created. As water flows down cave walls, it deposits calcite. When calcite forms it contains trace amounts of U-238. This isotope decays into Th-230. Normally, detection of such low quantities of these isotopes would require extremely large samples. The researchers discovered that by using accelerator mass spectrometry they could get by with 10-milligram samples.
By dating the calcite samples, they produced minimum and maximum ages for the cave paintings. While most of the 50 samples they took dated to around 25,000 years in age (or more recent than that), three were significantly older. They found a claviform-like symbol that dated to 31,000 years in age. They also found hand stencils that were 37,000 years old and, finally, a red disk that dated to 41,000 years in age.
Most anthropologists believe modern humans made their way into Europe around 40,000 years ago, prompting researchers to suggest that maybe Neanderthals created some of the cave art, “because of the 40.8 ky date for the disk is a minimum age, it cannot be ruled out that the earliest paintings were symbolic expressions of Neanderthals, which were present at Cantabrian Spain until at least 42 ka.”3
Dating the Art from Three Cave Sites in Iberia
Recently, this research team applied the same U-Th dating method to the art found in three cave sites in Iberia: (1) La Pasiega, which houses paintings of animals, linear signs, claviform signs, and dots; (2) Ardales, which contains about 1,000 paintings of animals, along with dots, discs, lines, geometric shapes, and hand stencils; and (3) Maltravieso, which displays a set of hand stencils and geometric designs.
The research team took a total of 53 samples from 25 carbonate formations associated with the cave art in these three cave sites. While most of the samples dated to 40,000 years old or less, three measurements produced minimum ages of around 65,000 years in age, including: (1) red scalariform from La Pasiega, (2) red areas from Ardales, and (3) a hand stencil from Maltravieso. On the basis of the three measurements, the team concluded that the art must have been made by Neanderthals because modern humans had not made their way into Iberia at that time. In other words, Neanderthals made art, just like modern humans did.
Are These Results Valid?
At first glance, it seems like the research team has a compelling case for Neanderthal art. Yet, careful examination of the U-Th method and the results raise some concerns.
First, it is not clear if the U-Th method yields reliable results. Recently, a team from France and the US questioned the application of the U-Th method to date cave art.4 Like all radiometric dating methods, the U-Th method only works if the system to be age-dated is closed. In other words, once the calcite deposit forms, the U-Th method will only yield reliable results if none of the U or Th moves in or out of the deposit. Unfortunately, it does not appear as if the calcite films are closed systems. The calcite films form as a result of hydrological activity in the cave. Once a calcite film forms, water will continue to flow over its surface, leeching out U (because U is much more water soluble than Th). This process will make it seem as if the calcite film and, hence, the underlying artwork is much older than it actually is.
In the face of this criticism, the team from the UK and Spain assert the reliability of their method because, for a few of the calcite deposits, they sampled the outermost surface, the middle of the deposit, and the innermost region. Measurements of these three samples gave ages that matched the expected chronology, with the innermost layer measuring older than the outermost surface. But, as the researchers from France and the US (who challenge the validity of the U-Th method to date cave art) point out, this sampling protocol doesn’t ensure that the calcite is a closed system.
Additionally, critics from France and the US identified several examples of cave art dated by both carbon-14 methods and U-Th methods, noting that the carbon-14 method consistently gives much younger ages than the U-Th method. This difference is readily explained if the calcite is an open system.
Secondly, it seems more plausible that the 65,000-year-old dates are outliers. It is important to note that of the 53 samples measured, only three gave age-dates of 65,000 years. The remaining samples gave dates much younger, typically around 40,000 years in age. Given the concerns about the calcite being an open system, should the 65,000-year-old samples be viewed as mere outliers?
Compounding this concern is the fact that samples taken from the same piece of art give discordant dates, with one of the samples dating to 65,000 years in age and the other two samples dating to be much younger. The team from the UK and Spain argue that the artwork was produced in a patchwork manner. But this explanation does not account for the observation that the artwork appears to be a unified piece.
What Does Neanderthal Biology Say?
The archaeological record is not the only evidence we have available to us to assess Neanderthals’ capacity for symbolism (and advanced cognitive abilities). Scientists can also glean insight from Neanderthal biology.
As I discuss in Who Was Adam?, comparisons of the genomes of Neanderthals and modern humans reveal important differences in a number of genes related to neural development, suggesting that there are cognitive differences between the two species. Additionally, the fossil remains of Neanderthals indicate that their brain development s took a different trajectory than ours after birth. As a result, it doesn’t appear as if Neanderthals experienced much of an adolescence (which is the time that significant brain development takes place in modern humans). Finally, the brain structure of Neanderthals indicates that these creatures lacked advanced cognitive capacity and the hand-eye coordination needed to make art.
On the basis of concerns about the validity of the U-Th method when applied to dating calcite films and Neanderthal brain biology, I remain unconvinced that Neanderthals made cave art, let alone had the capacity to do so. So, to me, it appears as if modern humans are, indeed, the “guilty party.” The entire body of evidence still indicates that they are the ones who painted the walls of caves throughout the world. Though, I doubt either my wife or I will have these early artists scrub down the cave walls as punishment. The cave art is much too precious.