DNA has an expiration date. But proteins reveal secrets about our ancient ancestors that we never believed possible.
As a creature dies, its DNA begins to break down. Half degrades each 521 years on average. About 6.8 million years, even in ideal preservation conditions in cold and stable environments, each significant trace has disappeared.
It is a huge challenge when you try to understand our evolving history more deeply: the two -legged primates emerged 7 million years ago in Africa, and our genre presented itself about 2.6 million years ago. But DNA quickly decomposes in places, our distant ancestors wandered. Consequently, many of the key adaptations that only make us a human date at a period when old DNA is indecipherable.
But a new technique allows us to return further than the expiration date of DNA in Africa, to answer long -standing questions about our ancestors. Called paleoproteomic, it is the study of ancient proteins, which last longer than DNA.
“Proteins are long -term biomolecules capable of surviving millions of years”, ” Christina Warinnera biomolecular archaeologist at Harvard University, and colleagues wrote in a 2022 paper. DNA code instructions to make amino acids, which combine long chains to make proteins. Because proteins collapse more slowly than DNA, they become an extremely precious resource for understanding human evolution.
Archaeologists and DNA revolution
The interest of archaeologists for ancient DNA has skyrocketed since 2010, when the researchers published a project of Neanderthal genomeConfirming that the Neanderthals mined with the ancestors of many modern humans. Since then, the technique has been used to answer a certain number of archaeological questions, as when Americas And Australia were installed when Agriculture has been inventedand how Languages and cultures Could have spread.
But there are major drawbacks to rely solely on old DNA. Even if DNA extraction techniques from very ancient bones have grown considerably over the years, DNA is broken down into smaller fragments during millennia due to the effects of sunlight, heat and humidity. Consequently, the DNA analysis of our old bones and our teeth has a time limit that prevents us from discovering our more distant evolution through this technique.
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This is an even more important problem in Africa, where most human developments have taken place.
“Africa is the center of our evolving past, and we do not have an old DNA in Africa beyond a scale of Maybe 20,000 years at this point,” Adam Van ArsdaleA biological anthropologist at Wellesley College, told Live Science. Knowing what was going on biologically with our distant ancestors millions of years ago in the heart of Africa would transform our understanding of human evolution, said Van Arsdale.
An explosion of protein analysis
Proteins are an exciting target for anthropologists because they can survive Even the oldest DNA. They have fewer atoms, fewer chemical bonds and a more compact structure, which means that they are less fragile than DNA, according to Warriner and his colleagues.
THE First old proteome – a group of proteins expressed in a cell, a fabric or an organism – was extracted from a 43,000 -year -old woolly mammoth bone in a study published in 2012. In 2019, the researchers announced the Oldest mammal proteo For the time: that of a tooth of 1.9 million million people from the extinct parent Glove. And in 2025, the researchers succeeded extracts the oldest proteins Yet of EpiacatheriumAn extinguished rhino -type creature lived in the Canadian Arctic more than 21 million years ago.
While we improve protein identification methods, anthropologists are starting to use these methods to answer questions about human evolution.
In a 2020 study Published in the journal NatureResearchers have analyzed the proteins of the enamel of the teeth Homo predecessorAn extinguished human parent who lived in Europe 800,000 years ago. They discovered that H. predecessor ‘Proteins s were different from those of H. SapiensNeanderthals and Denisovans, which makes it a distinct branch of our evolutionary tree rather than our direct ancestor.
In a study published in April in the journal ScienceProteomic analysis has also been used to understand that mysterious jaw In the early 2000s, in the early 2000s, off the coast of Taiwan, was linked to Denisovans, a group of extinguished human parents. Before that, the paleoanthropologists did not know if the Denisovans had lived in this part of the world. The analysis has also shown that it is possible to identify the proteins found in the fossils of hot and humid regions.
Our African roots
Paleoproteomic can be even more transformative to decipher our more distant evolution. Two recent studies on fossil bones and African teeth, where DNA studies are almost impossible, highlight the potential of the method.
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In the first, published in May in the review ScienceArchaeologists have recovered the old proteins from the teeth of four members of the species Strong paranthropusA human parent who lived between 1.8 million and 1.2 million years. They showed that two of the individuals were men and two were women. Surprisingly, however, the researchers discovered that one of the A. Robustus The individuals who were supposed to be men were in fact women. This suggests that some skulls previously classified as a sex of a known species can actually belong to unidentified groups or new species.
In the second study, published in February in the South African Science JournalThe researchers recovered the proteome from the enamel from the teeth Australopithecus AfricanusA human parent who lived in South Africa 3.5 million years ago. Although they were only able to identify the Biological sex of AustralopithecinsThe researchers wrote that “they are all incredibly exciting breakthroughs that are ready to revolutionize our understanding of human evolution”.
A question to which this analysis could help to answer is whether the men and women of our ancestors and our loved ones differ considerably in size or characteristics, Rebecca AckermannA biological anthropologist at the University of Cape Town, told Live Science. For example, the analysis of proteins and sex could reveal that some bones have already interpreted as men and women of the same species were in fact individuals of the same sex, but from different lines.
So far, however, scientists have managed to analyze proteins from a small number of former human ancestors. But while modern humans have more than 100,000 proteins In their body, the enamel “proteome” is tiny; It is made up of only five major proteins linked to enamel formation. However, the variation in protein sequences may be sufficient to differentiate between related organisms.
Future borders
Analysis of differences in these proteins probably does not provide sufficient resolution to answer key questions, such as the way in which the old human ancestors and parents were linked, Ackermann said. For example, millions of years ago in East Africa, several two -legged primates The species rided over timeBut if they could cross and create fertile hybrids is not clear of their bones alone.
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Could old proteins possibly help to answer this question?
Ackermann is carefully optimistic that technology will progress enough for paleoproteomic to clarify the evolutionary relationships between closely linked groups.
“That we can say more about hybridization is a good question,” she said.
Even thus, bone and enameled proteoms can never be detailed enough to distinguish individuals closely linked in the same way as genomes can add Ackermann.
But there is a chance that techniques will improve enough for scientists to extract millions of years of millions of years, added Ackermann.
Most of the proteins made by humans, including those that are part of the “dark proteo”, have not been analyzed, which means that we have little idea of what they are doing, wrote Warriner and his colleagues.
“The next 20 years will surely hold many surprises when we start to apply this analytical power to answer long-standing questions about the past and innovate new solutions to the old problems,” they wrote.
