In 1987, Rebecca Cann, Mark Stoneking and Allan Wilson published in the magazine Nature a study on mitochondrial DNA which indicated that the ancestral population of the Homo sapiens Today it probably came from East Africa.

In addition to indirect evidence, this explains why fossils from the first Homo sapiens more convincing (that is, Omo I or Omo Kibish and the Herto hominids), have also been found in this region.

However, recent studies, both in genetics and in paleoanthropology, began to question this point of view. In this way, the emerging consensus on the location of the origin of our species leans towards more complex evolutionary processes, which include mixing between different populations, originating from different regions of Africa, for example, the populations of southern and eastern of the continent. .

The fossil Omo I, discovered by the Kenyan paleoanthropologist Richard Leakey, has the main morphological characteristics specific to the Homo sapiens –That is, a high, globular cranial vault, a chin in the jaw–, which makes the specimen an unquestionable member of our species.

A team of scientists, led by the University of Cambridge (UK), dated a huge volcanic eruption in ethiopia which now reveals that this individual lived much earlier than previously thought.

They dated a massive volcanic eruption in Ethiopia, which now reveals that Omo I lived much earlier than previously thought.

“Prior to this study, these fossils were believed to be 198,000 years old. The new estimates are more than 200,000 years old and possibly more than 230,000 years old, thus delaying the first unquestionable appearance of a member of our species in the fossil record.” by the magazine Nature.

How I found myself under a layer of very thick gray which is very good for getting data by direct dating techniques. “The only way there was was to analyze its chemical composition to get its fingerprint and then try to correlate it with other ash layers in the region and, ideally, with the volcano that produced the eruption. Something very complex, because Ethiopia is home to many volcanoes. Each eruption has a unique chemical fingerprint,” says Celine Vidal, lead author of the work and a researcher at the University of Cambridge.

The Omo-Kibish Formation. / Céline Vidal 2018

A colossal eruption was the key

So far, several studies that have tried this dating have suggested some correlations, but there was a lot of uncertainty. What this team has now achieved, studying the major eruptions that occurred in Ethiopia during this period (between 300,000 and 60,000 years ago), is to identify one that was colossal, that of the shala volcano does 233,000 years.

The researchers collected rock samples from the volcanic deposits and crushed them to submillimetre size. “Once the rock was crushed, the minerals inside, and then the chemical signature of the volcanic glass that holds the minerals together can be dated and identified,” explains Vidal.

The researchers collected rock samples from volcanic deposits and ground them to submillimetre size.

The trace of this eruption turned out to be identical to the ash found on Omo I, in the Omo Kibish formation. This implies that the fossils are over 233,000 years old.

The valley that reveals the past of human evolution

This region of Ethiopia is an area of ​​high volcanic activity and a rich source of early human remains and artifacts such as stone tools.

“As a paleoanthropologist working in East Africa, I see how much I draw on Leakey’s achievements and legacy to conduct my own research. east of africa continues to provide numerous extremely important fossils. But it is not so much the fossils themselves, but the particularities of this area that make it important, as the remains are better preserved than in other regions and, specifically, the rift valley offers a unique opportunity by exposing older sediments and making them more accessible to archaeologists,” reflects Mounier.

This study is especially important because it supports the genetic research hypothesis that the Divergence of genes from the first populations of Homo sapiens could have happened about 300,000 years ago.

This study is especially important because it supports the genetic research hypothesis that the divergence of genes from early Homo sapiens populations may have occurred around 300,000 years ago.

“There are many other layers of ashes which we are trying to correlate with the Ethiopian Rift eruptions and ash deposits from other sedimentary formations. Over time, we hope to better limit the age of other fossils in the region,” says Vidal.

In search of the age limit of our species

The researchers say that while this study shows a new minimum age for Homo sapiens in East Africa, it is possible that new discoveries and studies extend age even further back in time.

“We can only date humanity based on the fossils we have, so it’s impossible to say that this is the definitive age of our species. The study of human evolution is always on the move: boundaries and timelines change as our lives improve. understanding. But these fossils show how resilient humans are: that we survive, thrive and migrate in an area so prone to natural disasters.”

“Our forensic approach provides a new minimum age for the Homo sapiens in East Africa, but the challenge remains to establish a limit, a maximum age, for its appearance”, concludes the co-author Christine Lane, director of the Cambridge Tephra Laboratory.

Source: SYNC

Rights: Creative Commons.

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