Until now, the paleontologists rebuilt the history of human evolution from fossils and ancient DNA extracted from these remains, but these two tools have limits: the fossil record is scarce, and the old DNA is not well preserved well after 20,000 years.
To overcome these problems, scientists began using paleoproteomics, a technique that allows recovering and analyzing fragments of fossil dental enamel proteins, which are kept longer than old DNA and that provide very important information.
With this technique, a team of scientists led by the University of Copenhagen (Denmark) and the University of Cape Cabo (South Africa), in which the Institute of Evolutionary Biology (IBE) and the Catalan Institut of Paleontology Miquel Crusafont participated, studied the oldest proteins of a human lineage, extracted from four teeth of Paranthropus Robustus, a kind of hominid that lived In Africa between 2.8 and 1.2 million years ago.
The study of these remains, whose details was published on Thursday in the journal Science, allowed to determine the biological sex of these hominids and also revealed a genetic variability that had not been detected so far in P. robustus.
According to the authors, these findings open new ways to understand the complex evolutionary history of these ancient relatives and confirm that paleoproteomic is a technique capable of shedding lights to issues that otherwise could not be addressed.
“Paleoproteomics has come to stay,” says IBE researcher and co-author of the study, Tomàs Marquès-Bonet.
Through paleoproteomic techniques, the researchers managed to extract proteins from the four fossil dental enamel of Paranthropus robustus, found in the Swartkrans cave (South Africa), between 2.2 and 1.8 million years of age (are some of the oldest fossils of this species).
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Proteins also manage to determine sex of Paranthropus
Paranthropus is a primitive relative of the human being who lived between 2.8 million and one million years ago, and coexisted with other hominids such as Australopithecus (the lineage of the famous ‘Lucy’) and with some homo genres.
And, although it was biped, he also showed adaptations in the upper extremities to climb and a wide food niche, based on various types of plants and possibly in insects.
“Paranthropus is one of the most mysterious branches of hominids. It is very robust and its face is clearly different from that of a modern human but we still do not know how it was connected to the modern human (H. Sapiens),” says the IBE researcher.
The analysis of the sequence of these proteins allowed to discover that two individuals were males and two others, females: “This may seem a simplicity but it is not because among scientists there are discussions when determining the sex of specimens, and with this study we have shown that you can find out in a molecular way,” says Marquès-Bonet.
Determining the chromosomal sex of individuals can be of great help for paleoanthropologists because it allows a more precise understanding of differences based on sex and social behaviors of our extinct relatives.
“Having determined the biological sex of these individuals who lived two million years ago is really remarkable. This fact opens the doors to understand the biology of other populations belonging to human lineage,” says Esther Lizano, a researcher at the Català Paleontology Institutology Miquel Crusafont (ICP) and co -author of the study.
But paleoproteomic also has limits because if sufficient proteins are not extracted, it is not possible to make a phylogenetic tree that allows to determine when the separation of the lineage of Paranthropus and the human lineage occurred.
“In this case, we do not get it because the two are extremely identical in their proteins, and this, in itself, is already an important fact because it indicates that at that time there was little genetic and proteomic diversity between species,” and that these Paranthropus were closely linked to the Homo lineage (the sapiens, Neanderthals and Denisovanos), the scientist points out.
What the researchers discover is that an individual is genetically different from others, “in the same way that there are also differences in some amino acids, which are the parts of the proteins,” says Marquès-Bonet.
In a separate explanation, the main author of the study, the South African Palese of Madupe, points out that to correct past errors based on a “colonial dynamic”, which historically appropriated the deposits, data and the African narrative marginalizing local researchers and communities, the study recognizes the work of Africans in this research.
“We hope that future research in this discipline will move away from helicopter research and orient towards a more ethical and socially responsible science, which focuses on African knowledge and elevates communities that are guardians of our fossil heritage,” concludes the African paleontologist.
With EFE information
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