An international team of scientists has made a remarkable discovery by extracting ancient proteins from a 24 million-year-old fossilized rhinoceros tooth. The event marks a significant breakthrough in the fields of paleontology and molecular biology, opening up unprecedented opportunities to study prehistoric life
on Earth.
The proteins obtained were ten times older than the oldest known DNA, allowing researchers to trace the evolutionary history of species, which was previously inaccessible to study by traditional methods. This achievement not only extends the chronological framework for the study of life, but also confirms the potential of a new scientific field - paleoproteomics.
Unique preservation: tooth enamel has become a "safe" for proteins
The key to this startling discovery was tooth enamel's unique ability to preserve biomolecules over millions of years. As Ryan Sinclair Paterson, a researcher at the Globe Institute at the University of Copenhagen who led the Canadian part of the study, explains, enamel acts as a natural "safeguard".
"The enamel is so hard that it protects these proteins for a long time," Paterson says. "It's basically like a safe. We've opened that safe, at least for this particular fossilized remnant."
Photo: edition.cnn.com
This natural "time capsule" allowed scientists to extract and analyze the oldest detailed protein sequence ever recorded. Found in the Canadian Arctic, the rhinoceros tooth had been in ideal conditions for preserving fragile organic molecules all along.
Paleoproteomics: a new era in archaeological science
The discovery of ancient proteins and the development of methods for analyzing them, known as paleoproteomics, promises to revolutionize paleontology in the same way that the study of ancient DNA has revolutionized archaeology. Until now, studies of ancient DNA have unlocked the mysteries of
lost civilizations, enigmatic clans, Ice Age creatures, and previously unknown human species, but their time frame has been limited by the fragility of the DNA molecule.
Proteins, on the other hand, consisting of sequences of amino acids, are much more resistant to degradation. Although they contain less detailed genetic information than DNA, proteins can shed light on the evolutionary history of a specimen, its diet and even the sex of an animal or human fossil, expanding the chronological horizons of research by millions of years. The study, published July 9 in the scientific journal Nature, vividly demonstrates the enormous potential of this new field.
Pushing the boundaries of knowledge
Enrico Cappellini, a professor at the University of Copenhagen and co-author of the study, as well as a pioneer in the field of extracting proteins from fossils, emphasizes the importance of further research: "The next step will be to prove that this is not just one sample, one happy accident."
Photo: edition.cnn.com
Cappellini expresses confidence that the potential of paleoproteomics is enormous, and this discovery could be just the beginning of a journey to unlocking the mysteries of much older organisms, all the way back to
dinosaurs. "
But potentially there's a huge area of research that could be further elucidated, and then if we really take it further ... we might even be able to start exploring dinosaurs," he added.
In this study, Cappellini and Paterson, together with colleagues at York University and the Canadian Museum of Nature, successfully reconstructed the sequences of seven proteins preserved in a fossilized rhinoceros tooth.
Sequencing of ancient proteins, that is, determining the order of amino acids in the sample, allowed scientists to obtain valuable information. By comparing these sequences with data from living and extinct relatives, the researchers were able to determine the place of this mysterious rhinoceros on the family tree.
The analysis showed that the rhinoceros split from the same family as modern rhinos about 41-25 million years ago: this allowed the classification of extinct rhinoceros species to be refined.
"There have been some unusual forms (of rhino species) in the fossil record. There's the woolly rhino, and you may have heard of the Siberian unicorn with the giant horn," Paterson said. "We were able to compare our mystery rhino with other forms and figure out where it is in the family tree."
Tropical discoveries: squirrels in hot regions of the world
Notably, a separate study, also published July 9 in the journal Nature, confirms that biomolecules can be preserved for millions of years even in hot tropical conditions. Scientists from the Smithsonian Institution's Institute of Museum Restoration and Harvard University analyzed 10 mammal fossils, including relatives of modern elephants, hippos and rhinos, from the Turkana Basin
in Kenya.
Photo: edition.cnn.com
They successfully extracted proteins from five fossils that ranged in age from 1.5 to 18 million years ago. This discovery disproves previous ideas about the need for low temperatures to slow protein decay and gives hope for the discovery of ancient proteins in fossils found in the warmest regions of the planet.
Although the information obtained from the Kenyan proteins was not as detailed as that from the Canadian sample, its presence in the enamel tissues of such ancient fossils in one of the warmest regions of the world is an extremely encouraging sign.
Timothy Cleland, a physicist at the Institute of Museum Restoration and author of the study, said, "We've had spectacular success. We've gone back about 18 million years. I think going back in time should be possible."
Skepticism and perspective: the road to the dinosaurs
Despite the exciting discoveries, the scientific community approaches them with justifiable caution. Maarten Dhaenens, a researcher at Ghent University in Belgium who specializes in proteomics, described the Canadian fossil study as "sound and extremely interesting," but expressed some skepticism about the methodology used for the Kenyan fossils, calling it complex and less well-tested.
He emphasized that the findings from the Kenyan samples are more difficult to interpret and require more careful evaluation, "The data are publicly available, so we should be able to verify their claims through manual inspection, but that takes time."
Evan Saitta, a paleontologist and research associate at the Chicago Museum of Natural History, called the discovery of proteins preserved in tropical latitudes "shocking" and noted the need to replicate these results. He argues that, if it is indeed true, "repeating this result should be very easy. We should be able to go around all the different fossil discovery sites around the world and find enamel peptides (proteins)." It was previously thought that low temperatures were needed to slow the breakdown of proteins.
Matthew Collins, a professor of paleoproteomics at the University of Cambridge in the United Kingdom, also recognized the compelling research on the Canadian fossil, but shared his experience of frustration in trying to extract proteins from ancient specimens: "It's amazing. It's really exciting, but at the same time I've been very disappointed in my career, thinking that we have very old proteins available and there weren't any."
Despite breakthrough advances in the study of rhinoceros proteins, the extraction of similar biomolecules from dinosaur fossils remains one of the most ambitious but also most challenging tasks for paleoproteomics.
Collins and Saitta, both of whom were not involved in the rhino studies mentioned, share their experiences in the field. In 2024, they were part of a team that succeeded in detecting amino acids in a fragment of a Titanosaurus egg shell. This plant-eating sauropod lived in the Late Cretaceous period, shortly before the mass
extinction of dinosaurs 66 million years ago.
However, despite the partial preservation of the chemical "building blocks," no identifiable protein sequences were found in the shell. Saitta figuratively compared their finding to the discovery of only five letters in a huge novel: it revealed only a general pattern of decomposition that indicated that proteins were once present in the egg shell.
Collins emphasizes this frustration, "There's no consistency, no information left, just little individual Lego building blocks (amino acids)."
Searching for proteins in dinosaur fossils is an extremely risky venture, and Saitta admits that he has personally shifted his research interests to other, more promising questions. He attributes this to several critical factors. First, the dinosaur fossils are much older than the rhinoceros specimens studied in recent research. Second, their period of existence largely occurred during
global warming, when the Earth was stripped of its ice caps, contributing to faster decay of organic matter.
Photo: edition.cnn.com
In addition, dinosaur fossils tend to be buried much deeper, subject to significant geothermal heating, further accelerating protein degradation. Finally, it remains questionable whether the enamel of dinosaur teeth was thick and strong enough to provide the same degree of protein protection as that of rhinoceroses.
Nevertheless, Cappellini and Paterson remain optimistic. They believe that it may be possible to extract valuable protein information from dinosaur fossils in 10 years. Before fully immersing themselves in this task, however, they plan to focus on other intriguing questions in paleontology, such as how mammals were able to become the dominant class on the planet after the dinosaurs disappeared.
Paterson, however, does not give up hope for the future: "I do think that some sites may preserve proteins from dinosaurs that lived in the distant past. Maybe we can try to track down such specimens."
This suggests that despite the challenges, the dream of deciphering the "protein legacy" of giant reptiles continues to inspire scientists. And an exciting field of study, paleoproteomics will undoubtedly continue to expand the understanding of ancient life and
evolution on Earth, providing unprecedented opportunities to study long-extinct species.