New analysis of ancient human protein could unlock secrets of evolution | Evolution

Tiny traces of protein lingering in the bones and teeth of ancient humans could soon transform scientists’ efforts to unlock the secrets of our species’ evolution.

Researchers believe a new technique – known as proteomics – could allow them to identify the proteins from which the bodies of our predecessors were built and shed new light on the past 2 million years of the planet. history of mankind.

Analysis of these microscopic remains could then help solve major evolutionary mysteries such as the identity of the common ancestors of A wise man and the Neanderthals.

The ramifications of the technology would reflect the impact of the recently developed technology of analyzing ancient DNA which, over the past 20 years, has helped uncover dramatic secrets about mankind’s past. These include the discovery that many modern humans possess Neanderthal genes and that the two species must have interbred at some point in the last 100,000 years.

A British project to assess the promise of proteomics has just been launched and will be carried out by a team of scientists based in two major research centers in London: the Francis Crick Institute and the Natural History Museum. “We will spend the next three years carefully evaluating how much protein we can extract from fossils and what we can learn from the samples we get,” said Professor Chris Stringer, from the Natural History Museum. “I hope this will indicate that we can learn a lot about our past by studying ancient proteins.”

Part of the research will involve using a handheld scanner that can be passed over a fossil to reveal how much protein it contains. “That way we can focus on only the most promising skulls and bones,” Stringer said. “It is crucial that we do not try to take samples – however small – from fossils that have no proteins to offer us for study.”

The development of proteomics follows scientists’ success in analyzing DNA extracted from ancient human fossils. By studying fragments of genetic material from fossils, scientists have discovered that men and women of non-African descent carry certain Neanderthal genes. They also revealed the existence of a whole new species of primitive humans – known as Denisovans – from genetic material found in tooth and bone fragments in a Siberian cave.

But the analysis of ancient DNA has limits. “DNA is fragile and decays quite quickly, especially in hot conditions,” said Pontus Skoglund of the Francis Crick Institute. “So it’s mainly useful for studying fossils that are less than 100,000 years old and found in moderately cool or cold places.”

This last disadvantage is a particular problem for the study A wise man – a species that evolved in Africa. Ancient DNA is rarely found in skulls and bones from excavations there due to the hot conditions. Scientists therefore began to examine other methods for studying the biology of ancient men and women – and identified proteins as a key target.

Our bodies are made up of proteins whose manufacture is controlled by our DNA and thus, by unraveling their structure, we can better understand the composition of ancient individuals. Above all, proteins survive longer in warm conditions.

This last benefit offers the hope of gaining new knowledge about several puzzling newly discovered species. These include homo starA 300,000 year old hominin which was found in South Africa in 2013. The specimens appear to be primitive although other evidence suggests they also buried their dead. Moreover, the origins of Homo floresiensisa small archaic species of humans – nicknamed the hobbit people – found on the island of Flores in Indonesia has also puzzled scientists. Conditions at both sites mean no DNA has been found on the fossils so far, leaving scientists uncertain about the evolution of these unusual versions of humanity.

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And then there are the Denisovans. Although scientists have decoded their genomes, we still don’t know what they looked like, how they behaved or how they hunted. “These are all really intriguing species and we only have the wrong idea of ​​how they relate to us,” Stringer said. “So proteomics could definitely help there.”

However, there was a downside to using protein as a way to study our past, Skoglund added. “Proteins don’t hold as much information as DNA. They only hold about 1% of the maximum information you could get from a DNA sample. That means we’ll need a lot to be able to generate enough data to perform meaningful analysis. It may not be easy.

The skull of a newly discovered “hobbit” human species, Homo floresiensis, believed to have lived 18,000 years ago. Photography: Rex Features

Nevertheless, proteomics has already produced promising first results. Studies by Frido Welker of the University of Copenhagen have shown that collagen proteins found in a piece of hominid jawbone from Baishiya Karst Cave on the Tibetan Plateau in China match those of Denisovans.

“This is the first hint of what a Denisovan might have looked like and suggests that proteomics has a lot to offer to our understanding of human evolution,” Welker told the Observer last week. “It’s certainly encouraging.”

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