When genetics meets history: DNA barcoding rewrites art, archaeology, and botany. From works of art to herbarium samples: genetics reveals secrets hidden for centuries in cultural heritage.
Behind the surface of a painting, in the worn wood of an artifact, or between the yellowed pages of a herbarium, life continues to leave invisible traces. Traces that science is now able to read thanks to DNA barcoding, a technique developed in the early 2000s to catalog biodiversity and which has now become a powerful tool for art and archaeology (as well as other fields such as food safety).
From molecular biology laboratories to museums and botanical archives, DNA barcoding is bringing together worlds that were once distant: geneticists and restorers, botanists and art historians are collaborating to reveal the hidden identity of pigments, fibers, woods, and centuries-old plants. In this alliance between technology and humanism, DNA becomes a new language of memory, capable of telling stories that have remained silent for centuries.
TAKEAWAYS
A case in point: medieval wood
The story told by Jessica Frigerio, a researcher at the University of Milan Bicocca and an expert in the field of DNA barcoding, perfectly illustrates how this technology is transforming the way we investigate the past. “Together with the University of Milan Bicocca spin-off FEM2 – Ambiente, we collaborated on an archaeological site in central Italy, where a very ancient wooden artifact from the Middle Ages had been found,” says Frigerio. The circumstances of the discovery were shrouded in the typical vagueness that accompanies many archaeological excavations: “They sent us the sample with very little information, derived from a wooden fragment of considerable historical interest, to understand what tree species it was. They had hypothesized that it might be a larch, because in that historical period and in that region this species was indeed very common, but the doubt remained, and they needed definitive confirmation.”
After centuries in the ground, the medieval wood presented all the typical difficulties of archaeological materials: degradation, partial mineralization, and chemical alterations. Yet, despite these obstacles, genetic analysis yielded surprisingly clear results. “Even though it was an analysis of medieval material, we managed to obtain enough DNA for sequencing,” says Frigerio with a hint of satisfaction. “And since the goal was to distinguish between a larch and a willow, we succeeded perfectly. We identified the genus Larix, that of larch trees, confirming that it was not willow.”
This seemingly modest result was actually of fundamental importance to archaeologists. “In that case, they didn’t need a precise species, the identification of the genus was sufficient for their purposes,” explains the researcher. “We were able to provide concrete assistance in an archaeological context, i.e., in a more artistic-cultural field, by identifying a species that they had already hypothesized but for which they needed scientific confirmation.”
When time is not an insurmountable obstacle
This experience raises a fundamental question: to what extent can DNA withstand the passage of centuries? The answer, as is often the case in science, is: it depends. “Even with very ancient samples, results can be obtained, but we must be realistic about our expectations,” explains Frigerio. “It is difficult with processed or extremely degraded samples, but if scholars already have an initial idea and the analysis is well defined, then we can provide concrete answers.”
The secret lies in the specificity of the scientific question. When it comes to distinguishing between two or three candidate species, already identified through the archaeological, historical, and geographical context, DNA barcoding can provide the decisive answer even on materials that have survived the centuries. “It’s not magic,” emphasizes the researcher, “but using the technique in the right way, with realistic expectations and in combination with other information.”
From wood to fibers, from pigments to dyes
The possibilities offered by DNA barcoding in the field of cultural heritage go far beyond the identification of ancient woods. “You can analyze historic buildings, boats, any wooden artifact of archaeological or artistic interest,” lists Frigerio. But the horizon extends to even more diverse materials: plant fibers found in ancient fabrics, baskets, ropes, mats, but also dyes and pigments of plant origin used in painting throughout the centuries.
“In paintings, dyes are sometimes of plant origin,” notes the researcher. “If we need to understand which plant a particular pigment came from, this is potentially an analysis that can be done. It has certainly been done by other research groups, just as we have done it for archaeological samples.” The botanical identification of a pigment can reveal valuable information about the trade routes of the time, the painting techniques used, and even the authenticity or dating of a work.
However, there is a critical aspect that cannot be ignored. “As we know, ours is a destructive analysis,” warns Frigerio in a serious tone. “We have to take a sample and destroy it to extract the DNA. So we always have to make very careful assessments on a case-by-case basis.” This is an ethical and practical dilemma that accompanies many scientific analyses of cultural heritage: the need for knowledge must always be balanced with the need for conservation.
“Obviously, if you can remove a small fragment of pigment, a tiny portion, without damaging or defacing the work, then you can do so,” continues the researcher. “In the case of the archaeological site I mentioned, they sent us a very small piece, which did not affect the value of the artifact in any way.” But when it comes to works of art of great value, the issue becomes more delicate: “In the case of an important painting, you can’t just scrape away material at will. Careful evaluation by restorers and conservators is required.”
Botanical gardens and herbaria: hidden treasures in historical collections
While the archaeological and artistic applications of DNA barcoding are fascinating, it is perhaps in the field of historical botanical collections that this technique is showing its most revolutionary potential. Herbaria, those collections of dried and pressed plants that constitute humanity’s botanical memory, and botanical gardens, custodians of living biodiversity, are proving to be largely unexplored mines of genetic information.
“The application of DNA barcoding to botanical gardens and herbaria is very useful for improving and increasing the value of collections,” explains Frigerio. “It may happen that the species present in a herbarium monograph, or the species of a plant grown in a botanical garden, has been incorrectly identified.” This statement may seem surprising, but it can be explained by the inherent difficulties of traditional botanical identification.
“Botanical gardens in particular may lack all the dichotomous keys necessary for reliable identification,” explains the researcher. Dichotomous keys are systematic tools that allow a plant to be identified through a series of binary choices based on morphological characteristics: presence or absence of hairs, leaf shape, flower structure, and so on. The problem is that not all of these characteristics are always present or observable.
A concrete case perfectly illustrates this problem. “We collaborated with a botanical garden on sage. They had a large collection of different species of Salvia, and with DNA barcoding, they discovered that three species had actually been misidentified by the botanical garden,” says Frigerio. The reason? “The flower was missing when the initial identification was made. So, without that dichotomous key that was essential for distinguishing the species, they had assumed the wrong species.”
The botanical garden experts, aware of this possible source of error, decided to verify their identifications. “They had us check the samples, and we actually proved to them that the identifications were incorrect,” continues the researcher. “Then, at the time of flowering, morphological analysis can certainly confirm the correct species by combining both genetic and morphological data. But there are times during the plant’s growth when this is difficult, and so DNA analysis can be used to complement traditional morphological analysis and help to provide the correct identification in case of errors.”
Correcting historical errors in herbariums
Herbariums are an even more fascinating case. These collections, some of which date back to the Renaissance, contain millions of plant specimens collected over the centuries by botanists, explorers, and naturalists. Each specimen is accompanied by a label – the “monograph” – which lists the scientific name, location of collection, date, name of the collector, and other valuable information.
“It is rarer to find identification errors in herbaria, of course, because in the case of a monograph, all the dichotomous keys are generally present,” notes Frigerio. “But it can happen, especially with older specimens, that the identification is not entirely correct.” There are many reasons for this: changes in taxonomy over time, limited botanical knowledge at the time of collection, simple human error. “With DNA barcoding, it is possible to correct the identification of species, thereby increasing the scientific value of a collection.”
But the potential goes beyond simply correcting errors. “One very interesting thing that can be done is to study the entire evolutionary and biogeographical history of various species over the centuries,” explains Frigerio enthusiastically. “Because herbariums may contain the same species collected in different years, perhaps even in different centuries – there are samples from the 1700s, even older – and so with DNA analysis, we can see how the species has evolved over time and how it has been distributed geographically.”
Of course, this is not a task that can be done with DNA alone. “It is a complex analysis, and obviously other data must also be taken into account, such as information from historical monographs,” the researcher points out. “However, without the link provided by DNA, it would not be possible to reconstruct this evolutionary history. DNA provides the common thread that allows us to connect specimens collected in different places and at different times.”
However, more sophisticated technologies are needed for this type of study. “Obviously, we need to use slightly more complex analyses, which analyze the entire genome or at least larger portions than standard DNA barcoding,” admits Frigerio. “But DNA barcoding can be an entry-level analysis to confirm the species and then allow for these more in-depth studies.”
The digital revolution: the NBFC project
The future of herbaria and botanical collections is increasingly digital and genomic. “As far as herbaria are concerned, there are some very interesting developments,” announces Frigerio. “We, together with the National Biodiversity Future Center (NBFC), are working on this. It is one of the main objectives of the platform we are creating.”
The project is ambitious: “Millions of plant monographs from the Florence herbaria have been digitized, and we are associating DNA analysis with these images,” explains the researcher. “In fact, when the platform is completed, integrated information will be available: the monograph can be consulted directly online, without having to request it physically, and genetic analysis will also be associated with it, with DNA barcoding sequences available for consultation.”
This is a revolution in the accessibility of botanical knowledge. Researchers from all over the world will be able to access not only images of historical specimens, but also their “genetic barcodes,” opening up research possibilities that were unimaginable until recently.
But the real innovation, the one that could radically change the way we work with historical collections, comes from the intersection of genetics and artificial intelligence. “Some very interesting work has been done at our center,” says Frigerio with obvious enthusiasm. “They are developing an algorithm with artificial intelligence to predict the success of DNA extraction from the monograph, i.e., from the image of the dried plant.”
The idea may seem like science fiction, but it has a solid scientific basis. “They are working on this algorithm, have already published the first results, and will continue to refine it,” continues the researcher. “The goal is to predict, simply by looking at the image of the herbarium specimen, the probability of being able to extract DNA of sufficient quality for barcoding.”
The practical advantage is enormous. “It can be very useful, especially for us researchers, because there is a consideration that comes naturally: a more recent sample, say from 2000, should have a better chance of success than one from 1800, right?” Frigerio pauses for effect. “Well, they have shown that this is not always the case. Age is not the only determining factor.”.
Storage conditions, drying methods, the species itself, and even the type of paper used to mount the specimen can affect DNA preservation. “The algorithm can provide an additional tool for making an informed selection,” explains the researcher. “Because when you go to a herbarium and look for a specific species, you can find many different monographs: different collection sites, different years, collected by different people. Artificial intelligence can help you make this choice, increasing the chances of success.”
And success is important, because working with herbarium samples is far from easy. “Herbarium samples are very degraded, so they are more difficult to work with than fresh material,” admits Frigerio. “It is not always possible to obtain intact DNA. Having a predictive tool can save time, resources, and above all, avoid unnecessary damage to precious specimens.”
Teamwork
The development of the algorithm is the result of a collaboration between different areas of expertise. “We didn’t develop it directly ourselves, but other groups within the center,” explains Frigerio. “The intention would be to provide a lot of herbarium material to help them refine this analysis. It would become a team effort, where molecular biologists, computer scientists, botanists, and herbarium curators would work together more than ever before.”
This multidisciplinary approach is emblematic of how DNA barcoding is transforming not only investigative techniques but also working methods in the field of cultural heritage and scientific collections. These are no longer separate disciplines running on parallel tracks, but an increasingly close integration of different skills.
Looking to the future, the applications of DNA barcoding in the fields of art, archaeology, and scientific collections seem set to expand further. As sequencing techniques become more sensitive, it will become possible to work with increasingly small amounts of material and increasingly degraded DNA. Reference databases, which contain the genetic sequences of different species, continue to grow, making identifications increasingly accurate and reliable.
Integration with other analytical techniques – spectroscopy, advanced microscopy, chemical analysis – promises to provide increasingly complete and detailed pictures. And artificial intelligence, as demonstrated by the Florentine herbarium project, can accelerate and optimize these processes, opening up possibilities that until a few years ago were pure science fiction.
“It’s a rapidly evolving field,” concludes Frigerio. “What seems extraordinary to us today will probably be routine in a few years. But the essence remains the same: using the best available technologies to preserve, understand, and enhance our cultural and scientific heritage. Every fragment of medieval wood, every ancient pigment, every herbarium plant has a story to tell. DNA barcoding is simply giving us a new way to hear it.”
This series dedicated to DNA barcoding stems from the experience gained in the laboratories of the University of Milan Bicocca and the National Biodiversity Future Center thanks to the FRONTIERS program.
