The oldest fossils of Homo sapiens identified in East Africa are not 200,000 years old: a new international investigation led by the University of Cambridge determined that the first humans died more than 230,000 years ago.
The age of the oldest fossils from East Africa, widely recognized as representative of our species, Homo sapiens, has been uncertain for a long time. Now, dating of a massive volcanic eruption in Ethiopia has revealed they are much older than previously thought: Previous research indicated they were less than 200,000 years old, but the new study shows they must be older than the colossal volcanic eruption, which It took place 230,000 years ago.
According to a press release, the remains known as Omo I they were found in Ethiopia in the late 1960s. Although it has been difficult to date them definitively, their human essence is unequivocal: unlike other fossils that are believed to belong to the first stages of the development of Homo sapiens, Omo I It has very clear human characteristics, such as a high cranial vault and the presence of a chin, among others.
Previous studies suggested that these fossils possess about 197,000 years old, but specialists have been unable to agree. It is that the chemical fingerprints of the layers of volcanic ash that are above and below the sediments, in which the fossils were found, do not provide total certainty about the age of these remains. Specifying the date is not a minor thing: it means determining the initial moment of humanity, at least based on current evidence.
The message from the ashes
To try to solve this enigma, researchers led by Dr. Céline Vidal, specialists from the Cambridge Department of Geography, worked on dating the thick layer of volcanic ash that is under the fossils, and that nobody had managed to date until now. The study was recently published in the journal Nature.
At the same time, scientists have tried to date all major Volcanic eruptions that took place in that area of Africa around the time of the rise of Homo sapiens, a period known as the late Middle Pleistocene. Comparing both questions, they thought that the dates of some of these eruptions could coincide with the age of the ashes discovered together with the fossils.
After collecting pumice stone samples from volcanic deposits, they were ground down to submillimeter magnitude. It is the only way to determine the rash fingerprint, which shows its own evolutionary history below the Earth’s surface, showing the direction that the magma followed. By crushing the rock, experts can release the minerals it contains and date it, thereby identifying the chemical signature of the eruption.
matching dates
A geochemical analysis designed to link the fingerprint of the thick layer of volcanic ash located under the human remains with data corresponding to an eruption, which took place more than 400 kilometers away in the same period, indicated that both elements have, at least, 230,000 years old. Also, since the Omo I fossils were found deeper than this ash layer, they are likely to be more than 230,000 years old.
Although this is marking a notable difference in relation to the moment in which the dawn of humanity, the scientists stressed that no date can be considered definitive. The study of human evolution is always on the move: boundaries and timelines are shifting as our understanding improves.
Reference
Age of the oldest Homo sapiens from eastern Africa. Celine M. Vidal et al. Nature (2022). DOI:https://doi.org/10.1038/s41586-021-04275-8