Direct Human Ancestor Homo Erectus Is Older Than We Thought

A Homo erectus skullcap found northwest of Johannesburg in South Africa has been identified as the oldest to date, in research published in Science. The hominin is a direct ancestor of modern humans, experienced a changing climate, and moved out of Africa into other continents. The discovery of DNH 134 pushes the possible origin of Homo erectus back between 150,000 and 200,000 years. (Image: Therese van Wyk, University of Johannesburg)
A Homo erectus skullcap found northwest of Johannesburg in South Africa has been identified as the oldest to date, in research published in Science. The hominin is a direct ancestor of modern humans, experienced a changing climate, and moved out of Africa into other continents. The discovery of DNH 134 pushes the possible origin of Homo erectus back between 150,000 and 200,000 years. (Image: Therese van Wyk, University of Johannesburg)

An unusual skullcap and thousands of clues have created a southern twist to the story of human ancestors, in research published in Science. The rolling hills northwest of Johannesburg are famous for fossils of human-like creatures called hominins. Because of this, the area is known as the Cradle of Humankind.

Stephanie Baker, who is a researcher and Ph.D. candidate at the Palaeo-Research Institute at the University of Johannesburg and manages research at the Drimolen fossil site in the Cradle of Humankind where the fragments of DNH 134 were found, said:

The international team was led by researchers from La Trobe University in Australia and Washington University in St. Louis in the United States.

Fossil forensics

Fossils that are millions of years old often come out of the soil in fragments. The fragments need to be rebuilt before researchers can confidently identify what kind of animal they came from. Baker said:

They named the skullcap DNH 134. One of our direct human ancestors is older than we thought. The Cradle of Humankind northwest of Johannesburg, South Africa, has yielded its first Homo erectus fossil, and the oldest found anywhere. Homo erectus experienced a changing climate and moved out of Africa into other continents. The discovery of skullcap DNH 134 pushes the possible origin of Homo erectus back between 150,000 and 200,000 years.


The next question was — what kind of hominin? The Cradle of Humankind has several different species of human ancestors and the Drimolen site had at least two kinds. Baker said:

Homo erectus is one of our direct human ancestors and is best known for migrating out of Africa into the rest of the world. These hominins walked upright and were a more human-like species than the other hominins found in the Cradle. They had shorter arms and longer legs. They could walk and run for longer distances over the African grasslands than the others.

How old?

Once the question of “which species?” was answered, two other huge questions presented themselves. How long ago was this individual alive? And how old were they when they died? The researchers knew that no other Homo erectus fossils had ever been found in South Africa before. Even more surprising was the time period suggested by the soil layers the skull fragments were found in. Baker said:

A Homo erectus skullcap found northwest of Johannesburg in South Africa has been identified as the oldest to date, in research published in Science. The hominin is a direct ancestor of modern humans, experienced a changing climate, and moved out of Africa into other continents. The discovery of DNH 134 pushes the possible origin of Homo erectus back between 150,000 and 200,000 years.

Building a 3-D puzzle over time

Trying to figure out how old fossils are from the caves west of Johannesburg is quite tricky. There were no volcanoes during the time of the hominins, so there are no ash layers to give the researchers quick age estimates, like they use for eastern African sites. But while they were uncovering the fragments at Drimolen, they kept and recorded every clue they could find. This included fragments of small animals like bats and lizards, but also things like soil samples.

They can also tell exactly where in 3-D-space in the Drimolen quarry each little fossil fragment was found. Then the research team used every possible dating technique available to get the most accurate possible date for the deposit. This included Palaeomagnetic dating, Electron spin resonance, Uranium lead dating, and faunal dating.

Possible shifted, earlier origin

Baker said:

That means that DNH 134 is much older than the next oldest Homo erectus in Africa. Professor Andy Herries, who is the project co-director with Ms. Baker, lead researcher, and head of the Department of Archaeology and History at La Trobe University in Australia and an associate in the Palaeo-Research Institute at UJ, said:

DNH 134 cranium with styalised projection of the outline of the rest of the skull. (Image: Andy Herries, Jesse Martin and Renaud Joannes-Boyau)

DNH 134 cranium with styalised projection of the outline of the rest of the skull. (Image: Andy Herries, Jesse Martin and Renaud Joannes-Boyau)

Because Homo erectus is one of our direct ancestors, the discovery has implications for the origins of modern humans. Baker added:

The skull is also unusual because it is the skull of a young Homo erectus. Herries said:

The Drimolen excavations and excavated fossils. (Image: Andy Herries)

The Drimolen excavations and excavated fossils. (Image: Andy Herries)

The age of the DNH 134 skullcap shows something else — that three species of early human ancestor lived in southern Africa at the same time at the Drimolen fossil site. Herries added:

The drimolen fossil site. (IMage: Andy Herries)

The drimolen fossil site. (IMage: Andy Herries)

This might mean they needed to use different parts of the landscape to avoid competing with one another. For a start, they looked different. Paranthropus robustus hominins were shorter than Homo erectus and Australopithecus, says Baker, adding:

Changing weather

In comparison to the other two species, Homo erectus hominins were tall and slender. They ate things that are easier to digest, like fruits and berries. Baker said:

Gradually, the tree-cover diminished and grasses took their place. Eventually, the forests were replaced with the African savannah grasslands of today. The cooler weather suited the more mobile and social Homo erectus better. But it meant that Paranthropus had to rely on less desirable foods.

Provided by: University of Johannesburg [Note: Materials may be edited for content and length.]

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