This week, a team of scientists reported new finds of fossil bones Homosapiens, made in the Moroccan cave of Jebel Irhud, as well as the refined dating of the bones found there earlier. According to the authors, the people of Jebel Irhud are the oldest known members of our species.
The Jebel Irhud cave near the village of the same name is located about a hundred kilometers west of the city of Marrakech and 75 kilometers from the coast. It served as a barite (barium sulfate) mine. In 1961, workers discovered in it a well-preserved skull of an ancient man (known as Irhud 1). The cranium of an adult (Irhud 2) and the lower jaw of a child Irhud 3 were also found. The next year, more fragments of the humerus, the lower jaw of an adult and the pelvis were found (Irhud 4 and Irhud 5).
At first, bones from Jebel Irhud were identified as belonging to Neanderthals. Their age, according to the dating of the bones of mammals found nearby, was determined from 105-190 thousand years to 87-127 thousand years. In 2007, a revised date was proposed. Radiocarbon analysis of the bones of Irhud 3 showed an age of 160 thousand years. And the Irkhuds themselves were recognized or early Homosapiens, or their ancestors Homo heidelbergensis, or, along with several other members of a special species Homo helmei, transitional between the Heidelberg man and Homosapiens.
At that time, the age of 160 thousand years for the bones of our species was very solid, but still not a record. For the title of the most ancient Homosapiens claimed finds from two locations in Ethiopia. In 1997, at the Herto site, paleontologist Tim White and his colleagues found the skull of an adult male and other bone remains from 154 to 160 thousand years old (known as the Idaltu man, which means “oldest” in Amharic). But the most ancient representative of the species known to science was considered Omo I, whose cranium was found in 1967 in Omo-Kibish.
Now an international team of archaeologists and paleoanthropologists led by Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology and Abdelouahed Ben-Ncer of the National Institute of Archeology and Heritage of Morocco spoke about the new bones from Jebel -Irhuda. Scientists have found fragments of the bones of the skull and long bones of the arms and legs, as well as the lower jaw and teeth. They belong to at least five different people.
In the same layers, flint tools were found, as well as the bones of animals that served as food for ancient people. Most of the bones were gazelles, but among the hunting prey of the inhabitants of Jebel Irhud were also wildebeests, zebras, buffaloes, porcupines, hares, turtles, freshwater molluscs and even snakes. The large bones of the prey were cut open to extract the bone marrow. The flint, from which the tools were made, was delivered from a deposit about 30 kilometers from Jebel Irhud.
Jebel Irhud guns
Analysis of anatomical features convinced the authors of the work that there were no people living in Jebel Irhud. Homo helmei or representatives of some other archaic species, namely Homosapiens albeit with some ancient features. But in this case, the new dating of the bones, obtained by the researchers, becomes especially interesting.
This time, thermoluminescent dating was used. It is based on the fact that some materials are able to accumulate the energy of radiation radiation (space or from radioactive rocks), and when heated to a temperature of about 500 ° C, emit it in the form of photons. Accordingly, if the material is heated, then its "thermoluminescent counter" is reset to zero, and the accumulation of energy begins anew. Especially often thermoluminescent dating is used in geology to determine the age of rocks of volcanic origin, as well as in archeology when dating ceramics - the moment of "starting the counter" for it will be the moment of firing the item.
In Jebel Irhud, the use of thermoluminescent dating was made possible by the fact that silicon tools were found to have been heated in antiquity. Above them, the local inhabitants made fires. “We are fortunate that many of Jebel Irhud's artifacts have been heated in the past,” says geochronologist Daniel Richter. Scientists also clarified the dating of the tooth, which in 2007 was attributed to the age of 160 years. According to new data, after taking into account the radioactive background of Jebel Irhud, it turned out to be more ancient.
Thermoluminescent dating gave 14 dates, the average age of the finds is 314 thousand years (range from 280 to 350 thousand years). All this corresponds to the new radiocarbon date for the tooth - 286 ± 32 thousand years, as well as the age of the remains of a number of animals in the same layer.
What does all of this mean? If the assumption is correct that it was representatives of Homosapiens, then they turn out to be the most ancient known representatives of our species and, more importantly, it will be necessary to revise the most probable scenario of the most ancient stage in the history of mankind.
It was believed that modern humans originated in East Africa, in the Great Rift Valley zone, about 200 thousand years ago. They left Africa, according to various versions of the theory, from 100 to 60 thousand years ago. Now Jean-Jacques Hublin and his colleagues suggest that, firstly, Homosapiens appeared for at least a hundred thousand years, and secondly, even then it was much more widespread throughout Africa and lived far beyond the Great Rift Valley.
Do the people of Jebel Irhud look like Homosapiens... Really similar, although they have a number of archaic features. Moreover, what is remarkable, the facial part of their skull is more “progressive” than the cerebral one. The faces of the Irkhuds are almost modern. But the shape of the back of the head and the internal relief of the cerebral section of the skull are similar to the features of earlier representatives of the genus Homo... On the skull of Irhud 1, the so-called "chignon" is clearly visible - a variant of the structure of the occipital bone with a sharp bend between its upper and lower parts. It is found in Archanthropus and occasionally in Neanderthals. “Our evidence suggests that modern human facial morphology was established at an early stage in the history of our species, and that brain shape and possibly brain function evolved within the lineage Homo sapiens"Says paleoanthropologist Philipp Gunz of the Institute for Evolutionary Anthropology.
Composite Reconstruction of the Skull from Jebel Irhud
Reconstruction of the skull Irhud 10
Researchers do not claim that the people of Jebel Irhud were the direct ancestors of modern humanity. According to them, these ancient people were part of a vast population that occupied the entire territory of Africa from 300,000 to 330,000 years ago, when the Sahara was green. "Evolution Homosapiens happened on a continental scale, ”explains Philippe Guntz.
However, one should not forget that drawing boundaries between species in paleoanthropology is an interpretation of a set of features, some of which may speak in favor of one hypothesis, others - in favor of an alternative one. As we can see, the inhabitants of Jebel Irhud also had signs of archaic Homo, and signs of modern man. The final conclusion that a researcher draws will always depend on the weight he gives to certain features. Therefore, it is not uncommon for some authors to consider the found remains to be early Homosapiens with a lot of archaic features, while others are late Homo heidelbergensis.
Even if you disagree with the authors of the work in defining the inhabitants of Jebel Irhud as Homosapiens, in any case, their discovery is very interesting. For example, the more advanced character of the facial part of the skull and the more archaic - the cerebral, which they found among the Irhuds, is also observed in the ancestors of the Neanderthals about 400 thousand years ago. Perhaps the general conclusion that facial features during evolution Homo changed faster than the skull and brain. "This is a plausible argument that the face develops first," says paleoanthropologist Richard Klein of Stanford University. True, it is not yet clear how natural selection could have led to such a result.
As a result of the work, the researchers published two articles in the journal Nature. One of them contains a description of new finds from Jebel Irhud, the second is devoted to the problem of dating.