Face of mankind's oldest ancestor who roamed Earth 3.8 million years ago revealed

It has been reconstructed from a remarkably preserved skull.

The ape-like early human, or hominid, was a member of a species known as Australopithecus anamensis.

"It's good to finally be able to put a face to the name," said Dr Stephanie Melillo of the Max Plank Institute For Evolutionary Anthropology, who co-authored the report.

The almost complete skull, described in the journal Nature, was hailed by a British expert as an iconic relic of human evolution - revealing A. anamensis' features for the first time.

The 3.8 million-year-old cranium of Australopithecus anamensis is remarkably complete

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Named MRD, it belonged to an adult male. It was identified from its jaw and canine-like teeth.

The creature was dated from minerals in layers of volcanic rocks nearby. Its skull was kept intact by the sandy deposits of a delta where a river entered a lake.

The river likely originated in the highlands of the Ethiopian plateau. The lake developed lower down where rift activity caused the Earth surface to stretch and thin.

This created the lowlands of the Afar region.

Fossilised pollen grains and chemical remains of plant and algae in the lake and delta sediments provide clues about the ancient environmental conditions. 

Specifically, they indicate the watershed of the lake was mostly dry but there were also forested areas on the shores of the delta or along the side the river that fed the delta and lake system.

The cranium was discovered in 2016 at Miro Dora, Mille district of the Afar Regional State in Ethiopia

"MRD lived near a large lake in a region that was dry," said co-author Prof Naomi Levin of Michigan University.

"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."

Until now, A. anamensis was only known from partial upper and lower jaw bones, isolated teeth, a small part of the braincase and a few limb bones.

"Features of the upper jaw and canine tooth were fundamental in determining MRD was attributable to A. anamensis," said Dr Melillo.

It was dug up in the Woranso-Mille area of Ethiopia where many hominin bones have been unearthed.

The remains bridge the gap between A. anamensis and Lucy, one of the world's most famous fossils.

The facial reconstruction of "MRD" by John Gurche was made possible through generous contribution by Susan and George Klein

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She belonged to a species called Australopithecus afarensis - and rewrote the history of humanity.

When she was discovered in 1974 she was believed to be our oldest direct ancestor.  Other hominins pre-dating her have since emerged - including A. anamensis. 

Males of both species grew to about 5ft and weighed about 100lbs. The females were about 3dt5in tall and weighed around 62lbs.

A. anamensis is the oldest known member of the genus Australopithecus. Our own genus, Homo, is widely thought to have evolved from this group. The relationship is crucial to understanding where we all ultimately come from.

The MRD cranium, together with other fossils previously known from Ethiopia, show A. anamensis and A. afarensis co-existed for about 100,000 years.

This overlap challenges the widely-accepted idea of a straight transition between these two early human ancestors.

Lead author Dr Yohannes Haile-Selassie, of Cleveland Museum of Natural History, said: "This is a game changer in our understanding of human evolution during the Pliocene."

The Woranso-Mille project has been conducting field research in the central Afar region since 2004.

It has collected more than 12,600 fossils representing around 85 mammalian species. About 230 of the bones are from hominins dating back 3 to nearly 4 million years.

The first piece of MRD, the upper jaw, was found by local worker Ali Bereino in February 2016 at a place known as Miro Dora.

It was exposed on the surface and further investigation of the area resulted in the recovery of the rest of the skull.

Dr Haile-Selassie said: "I couldn't believe my eyes when I spotted the rest of the cranium. It was a eureka moment and a dream come true."

Due to the rare near-complete state of the skull, the researchers identified never-before-seen facial features of A. anamensis.

Dr Haile-Selassie said: "MRD has a mix of primitive and derived facial and cranial features that I didn't expect to see on a single individual."

Some characteristics were shared with later species, while others had more in common with those of even older and more primitive early human ancestor groups such as Ardipithecus and Sahelanthropus.

Dr Melillo said: "Until now, we had a big gap between the earliest-known human ancestors, which are about 6 million years old, and species like 'Lucy', which are two to three million years old.

"One of the most exciting aspects of this discovery is how it bridges the morphological space between these two groups."

She went on: "We used to think A. anamensis gradually turned into A. afarensis over time.

"We still think these two species had an ancestor-descendent relationship, but this new discovery suggests the two species were actually living together in the Afar for quite some. 

"It changes our understanding of the evolutionary process and brings up new questions - were these animals competing for food or space?"

This is based on a 3.9 million year old fragment of skull found in Ethiopia in 1981 that was assigned to A. afarensis.

It extends the earliest record of 'Lucy' back to this time - while MRD nudges the last appearance of A. anamensis forward to at least 3.8 million years.

Professor Fred Spoor, an expert in anatomy at London's Natural History Museum, said the skull is "a great addition to the fossil record."

Prof Spoor, who was not involved in the study, added: "This cranium looks set to become another celebrated icon of human evolution."   

 Source: The Mirror