© Céline VidalA view of the Omo-Kibish geological formation in southwestern Ethiopia.
The age of the oldest fossils in eastern Africa widely recognised as representing our species,
Homo sapiens, has long been uncertain. Now, dating of a massive volcanic eruption in Ethiopia
reveals they are much older than previously thought. The remains - known as Omo I - were found in Ethiopia in the late 1960s, and scientists have been attempting to date them precisely ever since, by using the chemical fingerprints of volcanic ash layers found above and below the sediments in which the fossils were found.
An international team of scientists, led by the University of Cambridge, has reassessed the age of the Omo I remains - and
Homo sapiens as a species. Earlier attempts to date the fossils suggested they were less than 200,000 years old, but the new research shows they must be older than a colossal volcanic eruption that took place 230,000 years ago. The
results are reported in the journal
Nature.
The Omo I remains were found in the Omo Kibish Formation in southwestern Ethiopia, within the East African Rift valley. The region is an area of high volcanic activity, and a rich source of early human remains and artefacts such as stone tools. By dating the layers of volcanic ash above and below where archaeological and fossil materials are found, scientists identified Omo I as the earliest evidence of our species,
Homo sapiens.
© Al DeinoResearchers at the Omo Kibish geological formation in southwestern Ethiopia.
"Using these methods, the generally accepted age of the Omo fossils is under 200,000 years, but there's been a lot of uncertainty around this date," said
Dr Céline Vidal from Cambridge's Department of Geography, the paper's lead author. "The fossils were found in a sequence, below a thick layer of volcanic ash that nobody had managed to date with radiometric techniques because the ash is too fine-grained."
As part of a
four-year project led by
Professor Clive Oppenheimer, Vidal and her colleagues have been attempting to date all the major volcanic eruptions in the Ethiopian Rift around the time of the emergence of
Homo sapiens, a period known as the late Middle Pleistocene.
© Celine M.Vidal, Christine S. Lane, et al.a, Map of the MER showing silicic volcanoes and the late Middle Pleistocene sedimentary formations and relevant tephra units. White boxes with blue edges depict former correlatives of the KHS Tuff6,8 b, Synthetic stratigraphic logs of the late Middle Pleistocene formations showing former correlations for the Alyio Tuff6 (green), Konso SVT (pink, also identified in the Chew Bahir sediment core33), new correlations for Konso unit TA-56 (yellow), and source eruptions (stars). LHM, lower Herto Member; UHM, upper Herto Member. c, Tephra ETH18-8 above the KHS Tuff at the KS locality in the Omo-Kibish Formation9.
The researchers collected pumice rock samples from the volcanic deposits and ground them down to sub-millimetre size. "Each eruption has its own fingerprint - its own evolutionary story below the surface, which is determined by the pathway the magma followed," said Vidal. "Once you've crushed the rock, you free the minerals within, and then you can date them, and identify the chemical signature of the volcanic glass that holds the minerals together."
The researchers carried out new geochemical analysis to link the fingerprint of the thick volcanic ash layer from the Kamoya Hominin Site (KHS) with an eruption of Shala volcano, more than 400 kilometres away. The team then dated pumice samples from the volcano to 230,000 years ago. Since the Omo I fossils were found deeper than this particular ash layer, they must be more than 230,000 years old.
"First I found there was a geochemical match, but we didn't have the age of the Shala eruption," said Vidal. The samples were sent to co-authors Dr Dan Barfodand Professor Darren Mark at the
Scottish Universities Environmental Research Centre (SUERC) in Glasgow so they could measure the age of the rocks.
"When I received the results and found out that the oldest
Homo sapiens from the region was older than previously assumed, I was really excited," said Vidal.
© Céline VidalOmo Kibish Formation in southwestern Ethiopia.
"The Omo Kibish Formation is an extensive sedimentary deposit which has been barely accessed and investigated in the past," said co-author and co-leader of the field investigation
Professor Asfawossen Asrat from Addis Ababa University in Ethiopia, who is currently at
BIUST in Botswana. "Our closer look into the stratigraphy of the Omo Kibish Formation, particularly the ash layers, allowed us to push the age of the oldest
Homo sapiens in the region to at least 230,000 years."
"Unlike other Middle Pleistocene fossils which are thought to belong to the early stages of the
Homo sapiens lineage, Omo I possesses unequivocal modern human characteristics, such as a tall and globular cranial vault and a chin," said co-author
Dr Aurélien Mounier from the Musée de l'Homme in Paris. "The new date estimate,
de facto, makes itthe oldest unchallenged
Homo sapiens in Africa."
The researchers say that while this study shows a new minimum age for
Homo sapiens in eastern Africa, it's possible that new finds and new studies may extend the age of our species even further back in time.
"We can only date humanity based on the fossils that we have, so it's impossible to say that this is the definitive age of our species," said Vidal. "The study of human evolution is always in motion: boundaries and timelines change as our understanding improves. But these fossils show just how resilient humans are: that we survived, thrived and migrated in an area that was so prone to natural disasters."
© GuillaumeGReproduction of the Omo-Kibish skull, Musée des Civilisations Noires de Dakar (Sénégal).
"It's probably no coincidence that our earliest ancestors lived in such a geologically active rift valley - it collected rainfall in lakes, providing fresh water and attracting animals, and served as a natural migration corridor stretching thousands of kilometres," said Oppenheimer. "The volcanoes provided fantastic materials to make stone tools and from time to time we had to develop our cognitive skills when large eruptions transformed the landscape."
"Our forensic approach provides a new minimum age for
Homo sapiens in eastern Africa, but the challenge still remains to provide a cap, a maximum age, for their emergence, which is widely believed to have taken place in this region," said co-author
Professor Christine Lane, head of the
Cambridge Tephra Laboratory where much of the work was carried out. "It's possible that new finds and new studies may extend the age of our species even further back in time."
"There are many other ash layers we are trying to correlate with eruptions of the Ethiopian Rift and ash deposits from other sedimentary formations," said Vidal. "In time, we hope to better constrain the age of other fossils in the region."
The research was supported in part by the Leverhulme Trust, the Cambridge-Africa ALBORADA Research Fund and the Natural Environment Research Council and the National Environmental Isotope Facility. Céline Vidal is a Fellow of
Fitzwilliam College, Cambridge.
Reference: Céline M. Vidal et al. '
Age of the oldest Homo sapiens from eastern Africa.'
Nature (2022). DOI: 10.1038/s41586-021-04275-8
Reader Comments
What is there in our past that existed or happened that the authorities are reluctant to disclose.
Frankly I tirer of this out of Africa nonsense, I believe mankind has a ghost in its closet and it needs to be exposed.
For those who know of me, I fight my pain and continue my life's journey, doing the things I love.
I will return a comment in the early hours UK Time.
66 million years ago the Dinasours became the victim of Earth's last major bombardment.
Since the introduction of mankind to planet Earth, there's been odd occasions where Earth's climate has adjusted as a consequence of volcanic activity and not cyclical activity.
Earth has largely existed without any major incidents and Earth's motion and relationship with its star, that it orbits, has become established.
Milankovitch was responsible for summarising all the interactions Earth endures and which result in the manufacture of Earth's weather.
So ice age's come and go, mankind has in its short time here on this planet had to endure only a few.
Yet Earth bears scars which were inflicted during human occupation, Early Egyptians, Egypt with their Pyramids, the Inca Empire, Peru and the mountainous Machu Picchu, both display the same evidence that supports the notion that a cataclysmic event happened, massively effecting both populations and resulting in the loss of previous technologies.
I believe that deities are very much associated with environment and how each civilization grew and harmonised with it, so resulting in so many Gods ,beliefs and traditions.
After the last Ice age, Europe became accessible again and slowly was repopulated by primitive mixed monadic tribes who were sadly lacking in any skills and technologies that had been demonstrated by civilisations elsewhere across the globe.
There's seems to be no uniformity or lineage evident as Mankind struggled to establish a footprint here on Earth, only latter day invasions resulted in a change of traditions by those who conquered lands and its people.
Only in the last few centuries has any attempt been made to record events here on Earth, the church and nobility being the ones mostly responsible for such things, if only to control and gather taxes.
Today technology has shrunk the world and instantaneous communications allow for no barriers, something our distant ancestors would not be able to comprehend even in their wildest dreams.
I made 5 batches of Chicken Madras curry, I add a mix of fruit in it, works exceptionally well. Curry was gorgeous, just enough heat balanced nicely by the fruit.
Glad to hear the chicken was so good! And nice to have some set aside for another day. Cheers!
Life is all about balance and how YOU, focus YOUR energy.
Reflection is the gateway to your inner self and once you have balance, you then can focus purposefully.
WN3