A month ago, an international team of researchers announced that it was necessary to push back by 100,000 years the date of appearance ofin Africa. Our ancestors would therefore have left their cradle earlier than we imagined, heading for Europe and Asia. Indirectly, here is a discovery, made in Australia, which supports this new possibility.
A team of Australian researchers has indeed published an article inexplaining that it has finally been possible to rigorously date the prehistoric site of the Madjedbebe rock shelter, not far from the famous , in northern Australia (this site has been on the UNESCO World Heritage List since 1981). The place has been excavated many times since the 1970s and fueled controversies between prehistorians and archaeologists concerning the date of the arrival of the first aborigines, therefore ofHomo sapiensin Australia.
A presentation of the Madjedbebe site. To obtain a fairly accurate French translation, click on the white rectangle at the bottom right. The English subtitles should then appear. Then click on the nut to the right of the rectangle, then on “Subtitles” and finally on “Translate automatically”. Choose “French”. © Gundjeihmi Aboriginal CorporationYoutube
Dating the arrival of aboriginal ancestors
From data collected from all known sites on the continent, two camps had formed:
- For some, Man probably arrived there at least 60,000 years ago.
- For the others, 50,000 years was probably the highest estimate of this arrival, which would rather have occurred 47,000 years ago.
To make matters worse, a new estimate, from thethis time, had recently provided a fairly wide time interval since the arrival of the ancestors of the aborigines could have occurred between 70,000 and 50,000 years ago approximately.
The Madjedbebe site is also known as Malakunanja II thanks to its rock art. Artifacts, in particular tools, were found in abundance in the sedimentary layers of the rock shelter and, as early as 1989, dating by the method ofhave suggested that it must be one of the oldest archaeological sites in Australia and that the stone tools it contained were probably cut between 60,000 and 50,000 years ago. However, these datings had been challenged by invoking processes that led objects to sink into the layers of thus biasing the estimates of the dates of their manufacture.
Two waves of migrationHomo sapiens in Australia ?
However, between 2012 and 2015, new excavations were undertaken taking careful account of the stratigraphic context. A new method of dating with atime, OSL technology (Optically Stimulated Luminescence or optically stimulated luminescence), could then be used to estimate the ages of the very many new artefacts discovered (some of the oldest stone axes in the world, millstones for pulverizing seeds and finely crafted stone points which served as spear points). The verdict is in: the oldest objects were unquestionably made between 70,000 and 60,000 years ago, with a most likely age of 65,000 years.
This discovery has several consequences in dominoes. Indeed, if Homo sapiens arrived earlier than thought in Australia, so it is quite possible that it also left Africa earlier than expected. But, to have arrived in Australia, he first had to pass through Southeast Asia and he may then have been in contact, more than 60,000 years ago, with, although there is no evidence to date.
The most interesting consequence is the following: genetics suggest quite strongly that the ancestors of the aborigines at one time partially hybridized with Neanderthals and. However, genetic clocks indicate that these mixtures of would have occurred between 53,000 and 45,000 years ago. If so, it seems that it conclude that Australia has experienced two of migration and that the most recent has led a population ofHomo sapiens to largely replace the oldest.
What you must remember
- In northern Australia, about fifty kilometers from the coast, and not far from the famous Kakadu National Park, the prehistoric site of the Madjedbebe rock shelter has yielded since the 1970s many artifacts attributed to the ancestors of the Aborigines. .
- New excavations and a new dating method have made it possible to specify the age of the oldest stone tools on this site: approximately 65,000 years. Before this discovery, several prehistorians thought that the arrival ofHomo sapiens was only made in Australia about 47,000 years ago.
- By combining this date with the genetics of the current aborigines, we come to the conclusion that the latter would largely derive from another, more recent wave of migration.
In Australia, it was man who made the megafauna disappear
Article by Bruno Scala published on 03/23/2012
Who of the Man or thewas right about Australian, about 40,000 years ago? Scientists are struggling to agree but it is the thesis of Man, hunter of these animals, which now holds the rope. The presence in the of Sporormiellaa living in the excrement of has put the events in order.
It is never easy to reconstruct the distant past and put events in the right order. Concerning I’of the megafauna in Australia, scientists are trying to understand who, man or the climate, is responsible. By tracing the chronology of events, Australian researchers have managed to determine the causes and consequences.
Their findings, set out in, are clear: the arrival of Man in Australia is prior to the disappearance of large animals, dated about 40,000 years ago, and these two stages took place before a profound change in the landscape. Men have therefore well hunted the big ones and are responsible for their disappearance. This partially confirms a 2010 study which was based on the and of back.
Sporormiellathe key coprophilic fungus to the riddle
To reach these conclusions, the scientists focused mainly on one characteristic: the presence of Sporormiella in the cores. It is a coprophilous fungus: it spends at least part of its life inside the excrement of large herbivores. If we do not findin the , is that the megafauna was absent. However, precisely, about 41,000 years ago, the content of Sporormiella dropped drastically. A sign that it was precisely on this date that the populations of large herbivores seriously declined.
What can be the cause? The climate or. The latter arrived in Australia around 45,000 years ago. So he makes a good candidate. As to , there is no trace of it. However, the researchers observed a strong change in the structure of the landscape: the mixed forests were indeed transformed into sclerophyllous forests (shrubs and bushes). But this step is later than the .
Disappearance of megafauna: the responsible man
According to the researchers, this change is due to a cascade of events, the primary cause of which is the arrival of humans. Following the extinction of herbivores, the vegetation – not maintained by grazing – was more exposed to fires and this is when the landscape change happened. Even more likely: humans have undoubtedly triggered manyfor the purpose of hunting game. The high content of of in the layers of the time attests the recrudescence of these fires. So everything is in order.
However, two weeks ago, a study published inindicated that the combined action of the was responsible for the extinction of megafauna across the globe over the past 100,000 years or so. The authors then indicated that it was more relevant to take the problem as a whole, on a large geographical scale. Nevertheless, according to the authors of the new study, no noticeable climate change took place at the time of the megafauna extinction in Australia. These differences confirm in any case that it is very difficult to reconstruct the events of the past.