New discoveries from an ancient Homo erectus skull

Study verifies the age of one of the oldest specimens of Homo erectus

April 13, 2021

A new study by researchers, including Arizona State University graduate student Maryse Biernat, verifies the age of one of the oldest specimens of Homo erectus, the first ancient species with humanlike body build and behavior.

While retracing the location of the original fossil discovery made at East Turkana, Kenya, in the 1970s, the researchers found two new specimens at the site, the earliest skeletal pieces of H. erectus yet discovered. The results of the study, led by Ashley Hammond of the American Museum of Natural History’s Department of Anthropology, are published this week in the journal Nature Communications. Students in the field Students looking for fossils by "crawling" along the landscape, examining every rock and bone for the possibility of discovering another part of a Homo erectus fossil. Ashley Hammond image. Download Full Image

“Homo erectus is the first hominin that we know about that has a body plan more like our own and seemed to be on its way to being more humanlike,” Hammond said. “It had longer lower limbs than upper limbs, a torso shaped more like ours, a larger cranial capacity than earlier hominins, and is associated with an advanced tool industry — it’s a faster, smarter hominin than Australopithecus and earliest Homo.”

In 1974, scientists at the East Turkana site found the original fossil — a large chunk of the occipital bone at the back of the skull — and dated it to 1.9 million years old. But some paleoanthropologists argued that the specimen, while showing peculiar features of Homo erectus anatomy, could have come from a younger deposit and was possibly moved by erosion to the spot where it was found.

Confirming the age of the East Turkana fossil is key to identifying the probable source of early Homo erectus at the Dmanisi site in the Republic of Georgia, which dates to 1.78 million years ago — the earliest collection of hominin fossils outside of Africa.

H erectus skull fragment

The inside of a Homo erectus skull fragment from East Turkana, Kenya found in 1974. Ashley Hammond image.

To pinpoint the correct location, the researchers revisited the site, relying on archival materials and geological surveys. The research team sifted through hundreds of pages from old reports and published research, reassessing the initial evidence and searching for new clues. Satellite data and aerial imagery were reviewed to find out where the fossils were initially discovered so that they could recreate the location of the original site and place it in a larger context for determining the age of the fossils.

Within 50 meters of this original fossil’s location, the researchers found two new hominin specimens: a partial pelvis and a foot bone. Although the researchers say they could be from the same individual, there’s no way to prove that after they’ve been separated for so long. 

“There’s no doubt that the anatomy of the original skull fragment implies that it should be assigned to Homo erectus,” said William Kimbel, ASU Institute of Human Origins director, who has studied the specimen but was not involved in the new study. “The team makes a strong case that the fossil is as old as the sediments on which it was found, making it among the oldest Homo erectus fossils in the world.”

The oldest fossil evidence for this species, dated at 2 million years old, was discovered in Drimolen, South Africa, where an international team, including ASU researcher Gary Schwartz, unearthed the earliest known skull of Homo erectus.

The scientists also collected fossilized teeth from other kinds of vertebrates, mostly mammals. From the dental enamel, they collected and analyzed dietary isotope data to paint a better picture of the environment in which early Homo erectus lived around early Pleistocene Lake Turkana.

Maryse Biernat

Maryse Biernat in the field looking for fossils. Image courtesy Maryse Biernat.

“Our analysis shows that the environment included a lot of grazing herbivores that preferred to live in open environments like grasslands,” said team-member Biernat, a graduate student in the School of Human Evolution and Social Change and an affiliated student in the Institute of Human Origins. “That’s the type of environment we think could have stimulated the evolution of some of the familiar humanlike features we see in Homo erectus.”  

The research is published as “New hominin remains and revised context from the earliest Homo erectus locality in East Turkana, Kenya,” Nature Communications, Ashley S. Hammond (American Museum of Natural History), Silindokuhle S. Mavuso (University of the Witwatersrand) Maryse Biernat (ASU), David R. Braun (The George Washington University and the Max Planck Institute for Evolutionary Anthropology), Zubair Jinnah (University of the Witwatersrand), Sharon Kuo (The Pennsylvania State University), Sahleselasie Melaku (National Museum of Ethiopia and Addis Ababa University), Sylvia N. Wemanya (National Museums of Kenya and the University of Nairobi), Emmanuel Ndiema (National Museums of Kenya), David B. Patterson from the University of North Georgia.

Written in collaboration with the American Museum of Natural History.

Julie Russ

Assistant director, Institute of Human Origins


When three species of human ancestor walked the Earth

April 2, 2020

An international team including ASU researcher Gary Schwartz, has unearthed the earliest known skull of Homo erectus, the first of our ancestors to be nearly human-like in their anatomy and aspects of their behavior.

Years of painstaking excavation at the fossil-rich site of Drimolen, nestled within the Cradle of Humankind (a UNESCO World Heritage site located just 40 kilometers or around 25 miles northwest of Johannesburg in South Africa), has resulted in the recovery of several new and important fossils. The skull, attributed to Homo erectus, is securely dated to be 2 million years old. Homo erectus cranium Homo erectus cranium from Dimolen, South Africa. Credit Angeline Leece.

In a paper published this week in Science, the team of nearly 30 scientists from five countries share details of this skull — the most ancient fossil Homo erectus known — and other fossils from Drimolen and discuss how these new finds are forcing us to rewrite a part of our species’ evolutionary history.

The high-resolution dating of Drimolen’s fossil deposits demonstrates the age of the new skull to pre-date Homo erectus specimens from other sites within and outside of Africa by at least 100,000 to 200,000 years and thus confirms an African origin for the species.

The skull, reconstructed from more than 150 separate fragments, is of an individual likely aged between three and six years old, giving scientists a rare glimpse into childhood growth and development in these early human ancestors.

3D reconstruction of field site, Drimolen, South Africa

A 3D laser scan of Drimolen main quarry showing the discovery location of the new Homo erectus (DNH 134) and Paranthropus robustus (DNH 152) crania relative to the major site features and the position of the original fossil find the site (DNH 7).” Credit: David Strait

 Additional fossils recovered from Drimolen belong to a different species — in fact, a different genus of ancient human altogether — the more heavily built, robust human ancestor Paranthropus robustus, known to also occur at several nearby cave sites preserving fossils of the same geological age. A third, distinctive species, Australopithecus sediba, is known from 2-million-year old deposits of an ancient cave site virtually down the road from Drimolen.

“Unlike the situation today, where we are the only human species, 2 million years ago our direct ancestor was not alone,” said Andy Herries, project director and lead researcher from La Trobe University in Australia.

Gary Schwartz, a paleoanthropologist and research associate with ASU’s Institute of Human Origins, participated in the excavations and recovery of the new cranium, and as an expert in the evolution of growth and development, is continuing his work with the research team to analyze the many infant and juvenile specimens found at the site.

“What is really exciting is the discovery that during this same narrow time slice, at just around 2 million years ago, there were three very different types of ancient human ancestors roaming the same small landscape,” said Schwartz, who is also an associate professor in the School of Human Evolution and Social Change.. “We don’t yet know whether they interacted directly, but their presence raises the possibility that these ancient fossil humans evolved strategies to divvy up the landscape and its resources in some way to enable them to live in such close proximity.” 

Drimolen excavation site

Drimolen excavation site. Gary Schwartz is in the red hard hat. Credit: Andy Herries and Giovanni Boschian

The ability to date Drimolen’s cave deposits with such a high degree of precision, using a range of different dating techniques, allowed the team to address important broader questions about human evolution in this region of Africa.

Paper co-author Justin Adams from Monash University (Australia), a specialist in reconstructing paleohabitats based on the animals preserved at fossil sites, said the discovery now allows us to address what role changing habitats, resources, and the unique biological adaptations of early Homo erectus may have played in the eventual extinction of Australopithecus sediba in South Africa.

“The discovery of the earliest Homo erectus marks a milestone for South African fossil heritage,” said Stephanie Baker, project co-director and University of Johannesburg doctoral student.

Fieldwork will continue at Drimolen, expanding the excavations to include even more ancient components of the cave and to provide a more in-depth glimpse at the forces shaping human evolution in this part of the African continent.

Julie Russ

Assistant director, Institute of Human Origins