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Few things bring us closer to our ancestors who put face in a family photo album. The same thing happens with the human family. Probably, the recreation of the famous Lucy, the tiny Australopithecus afarensis that I was walking upright makes 3.2 million years in Ethiopia, have done more to popularize our evolution that the publication of a multitude of intricate studies. Isn’t it easier to empathize with a face that, despite the differences, it shows an incipient humanity? However, other hominid still more ancient, Australopithecus anamensis , for some the first that can be considered without any doubt part of our family tree (although, in paleoanthropology there are almost as many opinions as researchers), has so far remained away from the spotlight due to the scarce and little flashy remains found.
From this mysterious relative, the oldest of the australopithecines , just had a few fragments of the jaw and teeth counted, all of between 4.2 million and 3.9 million years ago. Impossible to get an idea of the appearance of its owner with a puzzle in which the main parts are lost. But, finally, the long-awaited discovery of an almost complete cranium of 3.8 million years in the area of Woranso-Mille, also in the ethiopian region of Afar, has allowed his entire face, shown for the first time this Wednesday in the journal “Nature”.
The skull of Australopithecus anamensis, from 3.8 million years ago, is remarkably full – Dale Omori, the Museum of Natural History ClevelandMacho adultoCráneo MRD – Dale Omori / Liz Russell / Natural History Museum of Cleveland
The new fossil, unearthed in 2016, only 55 km from where it appeared Lucy and baptized as MRD by the first letters of its number of collection, it belongs to what appears to be an adult male, of small size and clearly bipedal . It was identified as A. anamensis by his jaw, and canines unique. When it appeared after fifteen years of work at the site, “I could not believe it, it was a eureka moment and a dream come true”, says Yohannes Haile-Selassie, paleoanthropologist at the Natural History Museum of Cleveland (USA) and lead author of the study. “Their most striking characteristics are its small size (about 20.5 cm maximum length) and the constriction behind the orbits, something that it shares only with A. afarensis. In addition, the back of the head tilts like that of the apes”, explains to ABC in an email.
The face of MRD brings together in a single individual with a mix of traits: some primitive , as the canine teeth are large and less incisors, nape of the neck angle or the jaw forward -reminiscent of groups even older ones such as Ardipithecus (4.4 million years ago) and Sahelanthropus (6 million years) – and others who share with hominids, modern . Precisely, the discoveries and the assignment as A. afarensis, a fossil of 3.9 billion years ago known as the front of Belohdelie, have allowed scientists to deduce that A. anamensis and the species of Lucy, traditionally considered its descent, coexisted in Afar during a period of at least 100,000 years. “This does not falsify the hypothesis that one is the ancestor of the other. But their relationship was not linear as until now it was thought (what is known as anagénesis), but a cleavage (cladogénesis),” explains Haile-Selassie. The discovery changes the understanding of the scientists of the evolutionary process, and it raises new questions, as if both hominids competed for food or space.
Next to a lagoHaile-Selassie shows the skull – Natural History Museum of Cleveland
To learn the age of the MRD, a study was conducted stratigraphic of the area, full of volcanic rocks that were analyzed in the light of modern dating techniques such as paleomagnetism. In this work, which are described in a supplementary article in “Nature”, participated Luis Gibert, of the School of Earth Sciences at the University of Barcelona. “Currently, the Afar region is a semi-desert area, crisscrossed by several rivers along which there are a lot of life. Located in the north of the Rift valley, the tectonic activity is high and there is a lot of active volcanism. Ago to 3.8 million years ago, the situation could be similar”, says the researcher. Dating was not easy. The site is in a remote area that requires crossing the river Mille. During the campaign, geological, 2017, the heavy rain caused that the width of the river to go from 20 to 100 meters, making it difficult to work geological.
“we don’t know if (MRD), he was exactly where he was found, in the sediments of a delta which flows into a lake. The skull could be drawn, although given its conservation status, we do not believe that it comes from very far”, he says. The lake of a certain salinity and between 6 and 8 meters deep where he was to die australopithecus “was surrounded by trees, although the further away the atmosphere was more open and arid, with vegetation dominated by shrubs, perhaps similar to the present”, he adds. In his opinion, “that environment could offer a multitude of resources for individuals who already walked so biped”. Yes, the researchers do not yet know what was his diet. To get an idea, samples must be taken of the teeth, which requires a special permit from the ethiopian government.
Icon of the evoluciónReconstrucción of facial morphology – Matt Crow, M. H. N. C.
The project Moranso-Mille is gradioso. Has collected since 2004, more than 12.600 fossil specimens of 85 species of mammals. The collection includes about of 230 hominids dating back to between 3.8 and 3 million years ago. But there is nothing as exceptional as MRD. Fred Spoor, of the Natural History Museum in London and the Max Planck Institute for Human Evolution in Leipzig (Germany), underlines in an article accompanying the study in “Nature”, the importance that a single fossil can have in paleontology. No doubt that the new skull will become “another famous icon of human evolution”.
