The discovery is said to challenge previous assumptions of a linear transition between two early human ancestor species..
Scientists have recreated the face of an early human ancestor after a “remarkably complete” skull dating back 3.8 million years was found in Ethiopia.
Researchers dug up the cranium at the Woranso-Mille palaeontology site in the northeastern Afar region of the African country after 15 years of work.
Dr Yohannes Haile-Selassie, of Cleveland Museum of Natural History and Case Western Reserve University, said the discovery was a “game changer in our understanding of human evolution” as it challenges previous assumptions of a linear transition between two early human ancestor species.
The Australopithecus anamensis species is known to have existed between 3.9 million and 4.2 million years ago – but the newly discovered fossil is 3.8 million years old.
This means Australopithecus anamensis must have co-existed for around 100,000 years with the species that came next – Australopithecus afarensis (also known as Lucy).
The international team said: “A. anamensis was already a species that we knew quite a bit about, but this is the first cranium of the species ever discovered. It is good to finally be able to put a face to the name.”
Australopithecus anamensis is the oldest known species that is unambiguously part of the human evolutionary tree.
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Dr Haile-Selassie said uncovering the fossil was a “eureka moment” for his team, with most of the cranium having been found after the separate discovery of its upper jaw in February 2016.
The skull – detailed in the journal Nature – is one of more than 12,600 fossil specimens collected by the Woranso-Mille project since 2004, representing approximately 85 mammalian species.
In a companion paper published in the same journal, Professor Beverly Saylor of Case Western Reserve University and her colleagues explained how the age of the skill was determined.
Researchers dated minerals in layers of volcanic rocks nearby to come to their conclusion, mapping out the area using field observations and the chemistry and magnetic properties of the rock layers.
From there, they were able to reconstruct the landscape, vegetation and hydrology where the specimen – which has been labelled as MRD – died.
It was found in the sandy deposits of a delta where a river entered a lake, having likely flowed from the highlands.
The lake formed in an area of steep hillsides and volcanic eruptions that blanketed the land with ash and lava.
Other clues as to the environment in which the specimen lived were provided by fossil pollen grains and the chemical remains of plants and algae, which are preserved in the lake and delta sediments.
Study co-author Naomi Levin, from the University of Michigan, said: “MRD lived near a large lake in a region that was dry. We’re eager to conduct more work in these deposits to understand the environment of the MRD specimen, the relationship to climate change and how it affected human evolution, if at all.”
Source: Sky News