Where and when our ancestor Homo erectus developed has so far been controversial. Because although East Africa is considered the most likely “cradle” of this species, the oldest skull of a Homo erectus has so far come from Georgia. But now researchers in a cave in South Africa have discovered fragments of another, even older Homo-erectus skull. At 2.04 million years old, this skull is by far the oldest evidence of this early human species worldwide. Its age and the fact that it was found together with a skull of the paranthropus robustus species, which is almost the same age, provide new insights into a decisive period in the history of human evolution.
The development of Homo erectus is considered groundbreaking because this early human was the first of our ancestors to spread from Africa across large parts of Europe and Asia. Around 1.6 million years ago, he left his mark on the Indonesian island of Java, among others. In addition, fossil finds indicate that the Homo erectus was already relatively similar to us in the body, had a comparatively large brain and went like we did. In addition, he was probably the first early human to learn to use the fire and make hand wedges. However, it is still unclear where and when the first representative of this successful species emerged. Researchers have found some of the oldest tools, footprints and fossils of Homo erectus in East Africa, including a 1.63 million year old skull in Kenya. However, the oldest known relics of this type, at 1.8 million years ago, have so far come from Dmanisi in Georgia – which has caused anthropologists to find explanations.
A two million year old skull
But now a new find from South Africa brings a little more clarity to the confused early history of Homo erectus. It was discovered by Andy Herries from La Trobe University in Australia and his colleagues in a collapsed karst cave northwest of Johannesburg. The Drimolen cave has long been a well-known fossil site, in which more than 150 hominin relics, some bone and stone tools and animal bones have been found since 1992. A few years ago, an excavation team came across new fragments: “We could see that they were parts of a skull,” reports co-author Stephanie Baker from the University of Johannesburg. “But what exactly it was was not immediately apparent.” The fragments of the skull christened DNH 134 were therefore taken to the laboratory and have been thoroughly analyzed over the past few years. The researchers also used several mutually independent methods, including uranium-lead dating, paleomagnetic dating, electron spin resonance, and dating animal bones from the same site to determine the age of the skull.
The results are now available. Accordingly, the skull DNH 134 is a representative of the Homo erectus. This is supported by the drop-shaped appearance of the skull seen from above and the relatively large brain volume, according to Herries and his colleagues. A special feature is that this fossil does not come from an adult representative of this type, but from a two to three year old child. This alone makes the find a rarity. But the age of this skull is even more exciting: “We now know that the Drimolen site and the fossils it contains are between 2.04 and 1.95 million years old,” reports Baker. That means: The Homo erectus found in the South African Drimolen cave is the oldest in the world. “The skull DNH 134 is at least 100,000 to 150,000 years older than the Homo-erectus specimens from Dmanisi and more than 300,000 years older than the KNM-ER3733 skull from Kenya,” said Herries and his team. This shows that this early human existed earlier than previously thought.
Three hominins in the same place at the same time
And not only that: This oldest Homo erectus now also raises new questions about the origin of this species and its early distribution. “Up to this find, we always assumed that Homo erectus originated in East Africa,” explains Baker. However, the Dmanisi skull caused some researchers to speculate about the Eurasian origin of this species. According to Herries and his colleagues, their new discovery now proves that Homo erectus most likely originated in Africa. “Nevertheless, we are not saying that this species must have developed in South Africa,” they emphasize. DNH 134 shows, however, that Homo erectus soon spread more than 8000 kilometers after its creation.
The finding and the age of the Homo-erectus skull also prove that this human ancestor was not the only hominine in South Africa at the time. Because in the same find layer, Herries and his team have also discovered skull fragments of a Paranthropus robustus, a prehistoric man who was considered an early branch of human development. In addition, remains of the prehistoric Australopithecus have also been found in the same region. “We can now say that Homo erectus then shared the area with two other human forms, Paranthropus and Australopithecus,” says Herries. How and whether these species met each other at that time and how they differed in their way of life has yet to be researched. “But their presence suggests that these early human ancestors had developed strategies to divide the habitat and its resources among themselves,” said co-author Gary Schwartz of Arizona State University.
Source: Andy Herries (La Trobe University, Bundoora) et al., Science, doi: 10.1126 / science.aaw7293