DNA ANALYSIS FROM CAVE PAINTINGS:

                

DNA from sediment reveals history of Denisova Cave. Image from phys.org.

For some time now it has been possible for scientists to extract DNA from the sediments in caves, including human and hominin DNA. This leads me to speculate that perhaps we may also be able to detect DNA from manually applied cave paintings such as positive handprints and get an analysis of the artists themselves. Considering that the human body sheds cells constantly it would seem logical that any paint on a cave wall that was applied by hand might contain detectable DNA in human skin cells shed during the application of that paint. And with the advances in DNA analysis this might be a way to personal data such as skin color, eye color, gender, and other data that would allow us to generate a detailed picture of the artist.

Denisova Cave sediment. Image from sci.news.

“Organisms are constantly shedding cells throughout their lives. Humans, for example, shed some half a billion skin cells every day. Much of this genetic material is quickly degraded, but some small fraction is safeguarded for millennia through sedimentary mineral-binding and is out there waiting for us to recover and study it. Now, we can conduct some remarkable research by recovering an immense diversity of environmental DNA from very small amounts of sediment, and in the total absence of any surviving biological tissues.” (Donovan 2020)

       

Negative handprint on cave wall. Online image, public domain.

For the negatively applied handprint, the kind where the hand is placed on the wall of the cave as a stencil and paint is blown around it to leave the image of the hand in outline, we usually assume that the paint was blown from the artist’ mouth. This paint sample should then have traces of human saliva as well as cells shed from the lining of the mouth that could be detected and analyzed.

Much like modern paints, ancient paints were combinations of pigments providing the color, binders hardening and preserving the paint, and the vehicle or liquid that carries the other ingredients for application. For ancient artists the pigments were invariably natural materials such as ochers, colored clays, charcoal, and less commonly plant dyes and materials. The binder could be natural fats, resins, plant saps, milk or eggs. Another possibility was urine used as a mordant (a chemical that fixes a dye or paint by combining with it to form an insoluble compound). In the case of milk used as a binder it also provides the vehicle (as would urine) but most commonly the vehicle would probably have been water (one benefit of mixing your paint with urine would have been that it would not have to have been carried separately, the artist would have a readily available supply).

“So how did the DNA get there? The researchers can’t say exactly, but it wouldn't be too difficult. Humans shed DNA constantly. Any traces of urine, feces, spit, sweat, blood or hair would all contain minute bits of DNA. These compounds actually bind with minerals in bone, and likely did the same with minerals in the soil, preserving it, reports Charles Q. Choi at LiveScience.” (Daley 2017) Once the science of DNA analysis was developed scientists used it to find what life forms had existed prehistorically in a place by testing undisturbed soil samples. The results were surprisingly rich turning up DNA from virtually every animal and insect that had passed that way, and stratigraphy allowed researchers to estimate timelines for those occupations.

“As Lizzie Wade at Science reports, when the team first sequenced the DNA from the sediments, they were overwhelmed. There are trillions of fragments of DNA in a teaspoon of dirt, mostly material from other mammals, including woolly mammoth, woolly rhinoceroses, cave bears and cave hyenas. To cut through the clutter and examine only hominid DNA, they created a molecular “hook” made from the mitochondrial DNA of modern humans. The hook was able to capture DNA fragments that most resembled itself, pulling out fragments from Neanderthals at four sites, including in sediment layers where bones or tools from the species were not present. They also found more DNA from Denisovans, an enigmatic human ancestor found only in single cave in Russia.” (Daley 2017) So, if DNA can be retrieved from cave soil there would seem to be no reason that it could not also be retrieved from paint. This, however, would depend on human contact with the paint.

Positive handprints. Image from Shutterstock.

In his 1993 paper on cave paint analysis Jean Clottes wrote “In the large cave of Niaux, direct observation and macrophotographs have shown that on the panels of signs dubbed ‘the signpost panels’, located were three passages branch off, the paint for some of the dots and red lines had been applied with fingers. On a few, even the fingerprints can be made out.” (Clottes 1993) So, we do have examples of manually applied paint and, since we know that human skin is constantly shedding cells from the outer surface we may be able to detect DNA in these examples. This would also apply to positive handprints where the paint was applied to the hand which was then pressed to the stone.

The other example I mentioned above is the negative handprint where the hand is placed on the wall of the cave as a stencil and paint is blown around it to leave the image of the hand in outline, we usually assume that the paint was blown from the artist’ mouth. This paint sample should then have traces of human saliva as well as cells shed from the lining of the mouth that could be detected and analyzed.

            

Positive and negative handprints, Cueva de los Manos,Argentina. Image from pinterest.

So, to what extent could we hope to use these techniques to learn about the artist’s genetics? “This ancient DNA appears to be relatively widespread. The scientists tested sediments from nine known archaeological sites in Belgium, Croatia, France, Russia and Spain. The sediments dated from between 14,000 and 550,000 years ago, with the oldest intact DNA found in sediments dating from 240,000 years ago.” (Henriques 2017) These examples cited do not distinguish between mitochondrial and nuclear DNA.

B. Vernot et al. (2021) have developed techniques to retrieve and analyze nuclear DNA to retrieve even more data. “Mitochondrial DNA has been retrieved from cave sediments, but provides limited value for studying population relationships. We therefore developed methods for the enrichment and analysis of nuclear DNA from sediments, and applied them to cave deposits in western Europe and southern Siberia dated to between approximately 200,000 and 50,000 years ago. We detect a population replacement in northern Spain approximately 100,000 years ago, accompanied by a turnover of mitochondrial DNA. We also identify to radiation events in Neanderthal history during the early part of the Late Pleistocene. Our work lays the ground for studying the population history of ancient hominins from trace amounts of nuclear DNA in sediments.” (Vernot et al. 2021)

Genetic analysis of DNA can provide a world of information about the person that the DNA came from. Such things as gender, hair, eye and skin color, and even susceptibility to some diseases could be determined. With DNA it would be possible to learn if a painter had contributed more than one image to a panel, or images in more than one location. It may also be possible to determine the group identity and population dynamics of the painters once a sufficient number of samples have been identified and analyzed. 

I am in no way a geneticist so I pass this suggestion to someone who is, perhaps a graduate student looking for a thesis project. Will it not be exciting to actually get to know a cave painter on an individual basis? I, for one, can hardly wait.

NOTE: Some images in this posting were retrieved from the internet with a search for public domain photographs. If any of these images are not intended to be public domain, I apologize, and will happily provide the picture credits if the owner will contact me with them. For further information on these reports you should read the original reports at the sites listed below.

REFERENCES:

Clottes, Jean, 1993, Paint Analyses from Several Magdalenian Caves in the Ariega Region of France, Journal of Archaeological Science, 1993, 20, pp. 223 - 235. Accessed online 4 August 2024.

Daley, Jason, 2017, Scientists Extract DNA From Ancient Humans Out of Cave Dirt, 28 April 2017, Smithsonian Magazine Online, https://www.smithsonianmag.com. Accessed online 6 August 2024.

Donovan, Michelle, 2020, Thousands of species recorded in a speck of soil, 10 September 2020, News release, McMaster University, Hamilton, Ontario, Canada.

Henriques, Martha, 2017, DNA from ancient humans discovered in 240,000-year-old soil, 27 April 2017, International Business Times, 4 August 2017. Accessed online 5 August 2024.

Vernot, B. et al., 2021, Unearthing Neanderthal population history using nuclear and mitochondrial DNA from cave sediments, Science, 15 April 2021, www.sciencemag.org. Accessed online 4 August 2024.

WE MAY FINALLY HAVE AN EXAMPLE OF DENISOVAN ART- A LION CARVED OUT OF MAMMOTH IVORY IS ATTRIBUTED TO A DENISOVAN ARTIST:

Denisova Cave, Russia. Internet photograph, public domain.

While science still has a lot to learn about the mysterious hominids known as Denisovan after the cave in the Altai Mountains, Siberia, Russia, where they were first discovered, we now have a work of art and a number of artifacts that have been attributed to them. A small, carved piece of mammoth tusk that has been interpreted as the remaining piece of a broken carving of a cave lion (panthera spelea).

European cave lion. Image from dinotopia.com.

“This is the first such sculptural representation known in Siberia, throughout North and Central Asia, and the first zoomorphic sculpture of such antiquity. Zoomorphic figurines are known in the history of the Siberian Paleolithic, but they are usually no older than 23-21 thousand years. The age of this one is not yet established, but it is located in a stratigraphic context, which, according to the radiocarbon analysis performed at Oxford University and optically stimulated luminescence, is about 45 thousand years old. The chronology will still be specified, but the image is, in any case, not less than 30 thousand years old. This means, it is the most ancient artifact of this kind,’ says Head of the Department of Archeology of the Stone Age IAE SB RAS, Corresponding member of the Russian Academy of Sciences, Mikhail Shunkov.” (Russian Geographical Society) When the above stated “first such sculptural representation” it did not mean the first one ever discovered, many others have been previously discovered. It meant that as far as we know it may have been the first one created in that region.

Partial figurine identified as a cave lion. Image from Siberiantimes.com.

Carved figurine superimposed over a cave lion silhouette. Online image, public domain.

The figurine is carved out of mammoth ivory. The scientists believe that this means that the material had been carried to the site from 100 – 120 km away from Denisova from the Northern foothills of the Altai mountains. (Russian Academy of Sciences) Apparently there has been no evidence of mammoths within that distance of Denisova Cave to this point. This may, however, be a case of “your lack of evidence is not evidence of lack.”

Hematite crayon from Denisova Cave. Internet photograph, public domain.

“There have been other intriguing objects found within the cave. Some 30 pieces of mammoth ivory have been recovered from the cave. Among the most unique objects are fragments of a glistening green chlorite stone bracelet, beads made of ostrich eggs – and an ancient reddish-brown processed hematite ‘crayon.’” (Seidel 2019)

While the Cave Lion carving is tentatively dated to 45,000 BP by optically stimulated luminescence dating of the stratigraphic layer it was found in, many of the other recovered artifacts cannot share that age with it. One that very possibly does is the hematite ‘crayon,’ but I do not believe that the green stone bracelet can be anywhere near that age. Also carved of mammoth ivory are an eyed needle and what the discoverers are calling a tiara, a mammoth ivory piece that they interpret as a headband that tied around the forehead to keep long hair out of the wearer’s eyes. These may also be attributable to Denisovans, or may not. The reported dates are still not generally accepted, indeed, some believe that these mammoth ivory carvings are attributable to Neanderthals who lived in the Denisova Cave at a later date.

Mammoth ivory headband from Denisova Cave. Image from siberiantimes.com.

“In 2018, a simple tiara made from wooly mammoth ivory was found buried in its depths. It had a hole ground into its rounded end, where a cord was used to tie it at the back of the head. It’s been dated as having been made some 45,000 to 50,000 years ago. It was made to keep hair out of its wearer’s eyes. And it was discarded once it was broken. Was it made by the Denosivans? Or Neanderthals?” (Siedel 2019)

“Here we likely deal with another, more ancient culture, because there was not a single piece of bone belonging to a Homo Sapiens found in the cave’ Novosibirsk Institute of Archaeology and Ethnography researcher Alexander Fedorchenko told the Siberian Times. It’s a pressing question. And one not easily answered.” (Siedel 2019)

So, while at this time we cannot be certain who actually created these artifacts, the possibility that one or more of them may have been Denisovan is certainly exciting.

NOTE: Some images in this posting were retrieved from the internet with a search for public domain photographs. If any of these images are not intended to be public domain, I apologize, and will happily provide the picture credits if the owner will contact me with them. For further information on these reports you should read the original reports at the sites listed below.

REFERENCES:

Liesowska, Anna and Svetlana Skarbo, 2019, Cave Lion Figurine Made of Woolly Mammoth Tusk Found at Denisova Cave, 20 November 2019, Siberian Times, https://siberiantimes.com. Accessed online 28 March 2023.

Russian Academy of Sciences, 20 November 2019, An ancient figure of a cave lion was discovered in the Denise Cave, Siberian Division of the Russian Academy of Sciences, https://www.sbras.info. Accessed online 29 April 2023.

Russian Geographical Society, 2019, An Ancient Cave Lion Figurine Discovered in Denisova Cave, 24 November 2019, https://www.rgo.ru/en/ariticle/ancient-cave-lion-figurine-discovered-denisova-cave. Accessed online 28 March 2023.

Seidel, Jamie, 2019, Denisovan discoveries: Siberian cave studies reveal secrets of our mysterious lost ancestors, 31 January 2019, https://www.adelaidenow.com. Accessed online 8 May 2023.