For a long time, archaeological evidence showed that the oldest Homo sapiens dated 1975 years back. A recent discovery at the archaeological site of Jebel Irhoud in Morocco, however, proves that Homo sapiens existed after up to 300,000 years ago.This discovery pushes back the history of anatomically modern humans to 100,000 years. The findings were published in the July 8th issue of the journal Nature.
The fossils belonged to five individuals, among them a child and a teenager. Scientists say the fossils suggest that our species evolved at different locations across Africa contrary to the previous evidence indicating the evolution took place mainly in the eastern corner.
Researchers say the findings play a significant role in trying to explain when and where our species evolved from earlier lineages like Homo heidelbergensis and Homo rhodesiensis. Although the five individuals had facial structures that closely mimic that of modern day Homo sapiens, their brains had a smaller cerebellum — the part of the brain responsible for muscle coordination — and an elongated cranium.
The Jebel Irhound archaeological site began in 2004, but its excavation history began in the 1960s when scientists first found some of the fossils of the same individuals and the stone tools they used. At the time, the remains were dated 40,000 years old and classified as a neanderthal. However, there has been doubting as to whether those fossils were dated correctly. For instance, the layer of earth where the fossils were found was not specified. According to Jean-Jacques Hublin, a paleoanthropologist at Max Planck Institute, the new findings suggest that the previous remains found at the site belonged to about five persons; 3 adults, a teenager and an adolescent. He added that those individuals must have existed about 285 to 350 years ago.
"These dates were a big 'wow,' I would say. We realised this site was much older than anyone could have imagined," Hublin told Live Science. "This material represents the very root of our species — the oldest specimens ever found in Africa or elsewhere."
3D X-ray measurements and Computer models have been used to reconstruct the skulls of the fossils. One study suggests that although their brain case took an elongated shape like that of archaic human species, most of their facial features like jaw and teeth were structured the same as those of the present day people.
Researchers' studied the flint blades that were excavated in the same rock layer as the fossils. The study revealed that the stone artefacts were once heated by the flame. This shows the people at Jebel Irhound probably lit fires. Therefore, the fires would have been used to heat food, thereby heating the tools buried underneath. As much as the blades may have been mistakenly heated, this accident makes it possible to date the flints. In other words, they provide a historical clock.
In their study, Dr Hublin and his colleagues used thermoluminescence to date the blades. In this method, they heated the artefacts and observed how much light the crystals gave off. The amount of light emitted provide an indication of how much time had passed since the flints were heated. This technique of analysing artefacts revealed that the blades were estimated to be about 300,000 years old hence the bones found in the same sedimentary layer must have been the same age. DNA material was not recovered because of the heat and the age of the remains.
According to Teresa Steele, a paleoanthropologist at the University of California, animal fossils recovered at the site showed evidence of people who fed on gazelles, zebras and wildebeest among other game. She added that there were cuts and breaks on long bones which may be an indication that humans cut them open to feed on the bone marrow. Besides the above fossils remains of porcupines, hyenas, jackals, aurochs, hares, snakes, jackals, snails, tortoises, foxes, freshwater molluscs and leopards were also recovered from their site.
The earliest Homo sapiens must have existed over 300,000 years ago contrary to what the 195,000 fossils found at Omo-Kibish in Ethiopia suggested. This evidence alongside other discoveries across Africa like a 260,000-year-old partial skull excavated at Florisbad in South Africa shows us that Africa might be the birthplace of humankind. “We did not evolve from a single ‘cradle of mankind’ somewhere in East Africa. We evolved on the African continent." Said Philipp Gunz, a paleoanthropologist and co-author of the two fossil studies published in the journal Nature. Evolution must have taken place in various parts of Africa simultaneously. Different Homo Sapien populations may have been forced to get connected to changes in the environment, bringing about exchanges of innovations and genes.